Question about array append

Hi,
I have a for loop and an array outside the for loop. In each iteration some values are sent to the array.
For example, after first loop, I send following data to array:
2 3 4 5
4 5 6 7
after the second loop, other data send to array again and will overwrite the former data in array. How can I append the data to the array?
I try to use "Insert into array.vi", but how to keep the former array's data?
Thanks.

You have quite a few options.
The attached VI (LabVIEW 7.1) shows two possibilities, either building the table (2D string) or building the array (2D DBL).
(NOTES: If this is in a fast FOR loop it is not useful to update the display inside the loop, simply place the output terminals outside the FOR loop, connected to the shift registers on the right. If you know the final array size and it is relatively big, it is more efficient to initialize the shift register with the full sized array (e.g. filled with zeroes or NaNs), then replace array sections as you go in the loop. This avoids array resizing operations.)
LabVIEW Champion . Do more with less code and in less time .
Attachments:
temp_ni_MOD.vi ‏43 KB

Similar Messages

Question about arrays

I have a question regarding arrays. I have a contact class and two classes that extend from it a SchoolContact class and FamilyContact class. Right now as my code is I have three diffrernt arrays to hold all the info. Is there a way to store all this info into one array and print out only the School contacts at one time if the user enters that option or print out all the options at one time if the user selects that? my code is below
//The imports below are for I/O
import java.util.*;
import java.io.*;
// Declare a public class
public class CodeExample {
 public static void main(String[] args) {
 // Create scanner
 Scanner sc = new Scanner(System.in);
 //Declare array to hold school contact
 SchoolContact[] schoolContactInfo = new SchoolContact[10];
 FamilyContact[] familyContactInfo = new FamilyContact[10];
 Contact [] contactInfo = new Contact [10];
 // Declare variables
 int menuOption, creditHours, area, prefix, suffix, studentId, studentContactsSoFar = 0, familyContactsSoFar = 0, contactsSoFar = 0;
 double gpa;
 char studentData, familyRelationOption;
 String menuOption2, menuOption3;
 // Get menu to display
 do {
 System.out.println("-----MENU-----");
 System.out.println("1) Enter a Student Contact");
 System.out.println("2) Enter a Family Contact");
 System.out.println("3) Enter a Contact");
 System.out.println("4) Display Student Contacts");
 System.out.println("5) Display Family Contacts");
 System.out.println("6) Display Contacts");
 System.out.println("7) Display All Contacts");
 System.out.println("8) Quit");
 System.out.println("Selection:");
 menuOption = sc.nextInt();
 SchoolContact schoolContact = new SchoolContact();
 FamilyContact familyContact = new FamilyContact();
 Contact contact = new Contact();
 // Implement switch statement to
 switch (menuOption) {
 // If user enters 1 to create contact this will be displayed to user
 case 1:
 System.out.println("Enter The First Name of The Student");
 schoolContact.setFirstName(sc.next());
 System.out.println("Enter The Last Name of The Student");
 schoolContact.setLastName(sc.next());
 System.out.println("Enter the Student ID of this person: 900");
 schoolContact.setStudentId(Integer.parseInt("900" + sc.next()));
 System.out.println("G)Enter The GPA For This Student");
 System.out.println("H)Enter The Number Of Completed Credit Hours");
 menuOption2 = sc.next().toUpperCase();
 studentData = menuOption2.charAt(0);
 // Prompts the user for the next choice
 if (studentData == 'G') {
 System.out.println("GPA: ");
 gpa = sc.nextDouble();
 //create the Data object
 Data data = new Data();
 data.setStudentGPA(gpa);
 //add it to the contact
 schoolContact.setData(data);
 else if (studentData == 'H') {
 System.out.println("Hours: ");
 creditHours = sc.nextInt();
 //create the Data object
 Data data = new Data();
 data.setStudentCreditHours(creditHours);
 //add it to the schoolcontact
 schoolContact.setData(data);
 else {
 System.out.println("Invalid Entry");
 System.out.println("Enter The Phone Number of This Student");
 System.out.println("(###)-###-####: ");
 area = sc.nextInt();
 prefix = sc.nextInt();
 suffix = sc.nextInt();
 //create the phone object
 Phone_Number studentPhone = new Phone_Number(area, prefix, suffix);
 //add it to the Schoolcontact
 schoolContact.setPhone(studentPhone);
 //store info in an array
 schoolContactInfo[ studentContactsSoFar ] = schoolContact;
 //increase the counter to point to the next free location (if any)
 studentContactsSoFar++;
 break;
 case 2:
 System.out.println("Enter the First Name of The Contact");
 familyContact.setFirstName(sc.next());
 System.out.println("Enter The Last Name of The Student");
 familyContact.setLastName(sc.next());
 System.out.println("Enter The Relationship of This Contact");
 System.out.println("A) SISTER");
 System.out.println("B) BROTHER");
 System.out.println("C) MOTHER");
 System.out.println("D) FATHER");
 System.out.println("E) OTHER");
 menuOption3 = sc.next();
 familyRelationOption = menuOption3.charAt(0);
 if (familyRelationOption == 'A') {
 System.out.println("Relationship: SISTER ");
 familyContact.setRelationType(FamilyContact.RelationType.SISTER);
 else if (familyRelationOption == 'B') {
 System.out.println("Relationship: BROTHER ");
 familyContact.setRelationType(FamilyContact.RelationType.BROTHER);
 else if (familyRelationOption == 'C') {
 System.out.println("Relationship: MOTHER ");
 familyContact.setRelationType(FamilyContact.RelationType.MOTHER);
 else if (familyRelationOption == 'D') {
 System.out.println("Relationship: FATHER ");
 familyContact.setRelationType(FamilyContact.RelationType.FATHER);
 else if (familyRelationOption == 'E') {
 System.out.println("Relationship: OTHER ");
 familyContact.setRelationType(FamilyContact.RelationType.OTHER);
 System.out.println("Enter The Phone Number of This Contact");
 System.out.println("(###)-###-####: ");
 area = sc.nextInt();
 prefix = sc.nextInt();
 suffix = sc.nextInt();
 //create the phone object
 Phone_Number familyContactNumber = new Phone_Number(area, prefix, suffix);
 //add it to the familyContact
 familyContact.setPhone(familyContactNumber);
 //store info in an array
 familyContactInfo[ familyContactsSoFar ] = familyContact;
 //increase the counter to point to the next free location (if any)
 familyContactsSoFar++;
 break;
 case 3:
 System.out.println("Enter The First Name of The Contact");
 contact.setFirstName(sc.next());
 System.out.println("Enter The Last Name of The Contact");
 contact.setLastName(sc.next());
 System.out.println("Enter The Phone Number of This Contact");
 System.out.println("(###)-###-####: ");
 area = sc.nextInt();
 prefix = sc.nextInt();
 suffix = sc.nextInt();
 //create the phone object
 Phone_Number contactNumber = new Phone_Number(area, prefix, suffix);
 //add it to the contact
 contact.setPhone(contactNumber);
 //store info in an array
 contactInfo[ contactsSoFar ] = contact;
 //increase the counter to point to the next free location (if any)
 contactsSoFar++;
 break;
 case 4:
 System.out.println("-----Student Contacts-----");
 //print each stored contact
 for( int i = 0 ; i < studentContactsSoFar ; i++ )
 System.out.println( (i+1) + ". " + schoolContactInfo.toString() + "\n");
 break;
 case 5:
 System.out.println("-----Family Contacts-----");
 //prints each stored contact
 for( int i = 0 ; i < familyContactsSoFar ; i++ )
 System.out.println( (i+1) + ". " + familyContactInfo[i].toString() + "\n");
 break;
 case 6:
 System.out.println("-----Contacts-----");
 //prints each stored contact
 for( int i = 0 ; i < contactsSoFar ; i++ )
 System.out.println( (i+1) + ". " + contactInfo[i].toString() + "\n");
 break;
 case 7:
 System.out.println("Calling Case 7");
 for( int i = 0 ; i < contactsSoFar ; i++ )
 System.out.println( (i+1) + ". " + contactInfo[i].toString() + "\n");
 break;
 case 8:
 System.out.println("Program Ended");
 break;
 } while (menuOption != 8);

how would I go in printing the contacts from one array, then the next array and so on?
case 7:
 System.out.println("Calling Case 7");
 for( int i = 0 ; i < studentContactsSoFar ; i++ ) {
 System.out.println( (i+1) + ". " + schoolContactInfo.toString() + "\n");
for( int i = 0 ; i < familyContactsSoFar ; i++ ) {
System.out.println( (i+1) + ". " + familyContactInfo[i].toString() + "\n");
for( int i = 0 ; i < contactsSoFar ; i++ ) {
System.out.println( (i+1) + ". " + contactInfo[i].toString() + "\n");
break;

A question about arrays (brace yourself this is a long post)

I am working on an assignment that is about generating a random rabbit race by using arrays:
Rabbit Race
Write a program to simulate a race between 4 rabbits (numbered 0 to 3). Initially, all contestants are at the start of the race track (position 0) and must race on a 20 meter track (positions numbered 0 to 19). Each participant has its own technique; some run fast, but are sometimes lazy; while others run slowly but steadily. All rabbits make 1 movement one after the other and the one who arrives at the end of the track before the others, wins the race. Here are the rabbit?s strategies :
At each turn, rabbit 0:
- sleeps (so does not run), 50% of the time;
- runs 4 meters, 30% of the time;
- runs 3 meters, 20% of the time.
At every turn, rabbit 1 runs 2 meters.
At each turn, rabbit 2:
- sleeps, 30% of the time;
- runs 3 meters, 70% of the time.
At each turn, rabbit 3:
- runs 1 meter, 80% of the time;
- runs 10 meters, 20% of the time.
The difficulty in the race is that the track has little slippery hills. So after each movement, rabbits can slide down a hill bringing them either closer to the finishing line, or closer to the starting line. How much they slide and in what direction depends on the slope of the hill at their current position, and how many meters they ran during this turn. Each position (or meter) of the hill has a slope represented by an integer between -3 and +2. If the slope is :
- zero : then, there is no hill at this position and rabbits that reach this position stay there.
- a negative integer : then, there is a declining side of a hill at this position, and all rabbits reaching this position will slide down
to a new position that is closer to the finishing line. The new position will be the current position minus the slope times the number of meters the rabbit ran.
For example, assume a rabbit was in position 10, then ran 5 meters to position 15. If the slope at position 15 is -2, then the new position of the rabbit will be 15 - (-2 x 5) = 25.
- a positive integer : then, there is a rising side of hill at that position, and all rabbits reaching this position will slide down to a new position that is closer to the starting line. The new position will be the current position minus the slope times the number of meters the rabbit ran.
For example, assume a rabbit was in position 10, then ran 5 meters to position 15. If the slope at position 15 is +1, then the new position of the rabbit will be 15 - (+1 x 5) = 10.
Notes on the race:
- Rabbits have 40 turns to reach the finish line. If after 40 turns no one has managed to reach position 19 (or beyond), then the race is cancelled and no winner is declared.
- A rabbit?s position can never go below 0. If, after calculating a rabbit?s position, you arrive at a negative position (ex. position -3), then consider that it is at position 0.
- Consider that any position outside the track (ex. position 0 or position 20) has a slope of 0.
- If a rabbit reaches position 19 (or goes beyond it), it does not immediately win the race. If any other rabbit reaches position 19 (or beyond) during the same turn, then there is a tie.
- If at the same turn, one rabbit reaches position 19, and another reaches a position higher than 19, the second rabbit does not win the race because it went further than the first. They both win.
Ok I know this is long and boring to read but I already completed the majority of the assignment here is my code:
public class Assignment_3 {
 public static void main (String args[])
 int[] position = new int[20];
 int[] slope = new int[20];
 int[] moveRabbit = new int[4];
 moveRabbit[1] = 2;
 int[] currentPosition = new int[4];
 int currentPositionandSlope = 0;
 for (int i=0;i<position.length;i++)
 { position=i;
 System.out.print(position[i] + " ");
 System.out.println();
 for (int i=0;i<(position.length-5);i++)
 { slope[i]=(int) (-3 + Math.random()*5);
 for (int i=0;i<position.length;i++)
 System.out.print(slope[i] + " ");
 System.out.println();
 for (int turn=1;turn<=40;turn++)
 int randomNb0 = (int) (Math.random () * 100);
int randomNb2 = (int) (Math.random () * 100);
int randomNb3 = (int) (Math.random () * 100);
 if (randomNb0<=50)
 moveRabbit[0] = 0;
 else if (randomNb<=30)
 moveRabbit[0] = 4;
 else
 moveRabbit[0] = 3;
 if (randomNb2<=30)
 moveRabbit[2] = 0;
 else
 moveRabbit[2] = 3;
 if (randomNb3<=80)
 moveRabbit[3] = 1;
 else
 moveRabbit[3] = 10;
for (int j=0;j<=3;j++)
System.out.println ("Rabbit" + j + " is at position " + position[currentPosition[j]]);
if (slope[currentPosition[j]+moveRabbit[i]] < 0)
 currentPositionandSlope = position[currentPosition[j]+moveRabbit[j]] - (slope[currentPosition[j]+moveRabbit[j]] * moveRabbit[j]);
else if (slope[currentPosition[j]+moveRabbit[i]] > 0)
 currentPositionandSlope = position[currentPosition[j]+moveRabbit[j]] - (slope[currentPosition[j]+moveRabbit[j]] * moveRabbit[j]);
else
 currentPositionandSlope = (currentPosition[j]+moveRabbit[j]);
System.out.println ("it will move by " + moveRabbit[j] + ", but at position " + (position[currentPosition[j]] + moveRabbit[j]) + " there is a slope of " + slope[currentPosition[j] + moveRabbit[j]]);
System.out.println ("so it will slip by " + (position[currentPositionandSlope] - moveRabbit[j]) + " positions, and end up at position " + position[currentPositionandSlope]);
currentPosition[j] += currentPositionandSlope;
*Ok basically my question is that in the assignment there is an example output where the rabbit is at position 21 but the array is only 20 in length and my program crashes if i go beyond the array length.*
The example output is here:
Welcome to the 4 rabbit race:
position: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
slopes: 0 0 1 -2 1 0 -1 -1 1 -2 1 0 -1 -1 1 0 0 0 0 0
TURN #1
rabbit 0 is at position 0
it will move by 3, but at position 3 there is a slope of -2
so it will slip by 6 positions, and end up at position 9
rabbit 1 is at position 0
it will move by 2, but at position 2 there is a slope of 1
so it will slip by -2 positions, and end up at position 0
rabbit 2 is at position 0
it will move by 3, but at position 3 there is a slope of -2
so it will slip by 6 positions, and end up at position 9
rabbit 3 is at position 0
it will move by 1, but at position 1 there is a slope of 0
so it will slip by 0 positions, and end up at position 1
TURN #2
rabbit 0 is at position 9
it will move by 0, but at position 9 there is a slope of -2
so it will slip by 0 positions, and end up at position 9
rabbit 1 is at position 0
it will move by 2, but at position 2 there is a slope of 1
so it will slip by -2 positions, and end up at position 0
rabbit 2 is at position 9
it will move by 3, but at position 12 there is a slope of -1
so it will slip by 3 positions, and end up at position 15
rabbit 3 is at position 1
it will move by 1, but at position 2 there is a slope of 1
so it will slip by -1 positions, and end up at position 1
TURN #3
rabbit 0 is at position 9
it will move by 3, but at position 12 there is a slope of -1
so it will slip by 3 positions, and end up at position 15
rabbit 1 is at position 0
it will move by 2, but at position 2 there is a slope of 1
so it will slip by -2 positions, and end up at position 0
rabbit 2 is at position 15
it will move by 3, but at position 18 there is a slope of 0
so it will slip by 0 positions, and end up at position 18
rabbit 3 is at position 1
3
it will move by 10, but at position 11 there is a slope of 0
so it will slip by 0 positions, and end up at position 11
TURN #4
rabbit 0 is at position 15
it will move by 0, but at position 15 there is a slope of 0
so it will slip by 0 positions, and end up at position 15
rabbit 1 is at position 0
it will move by 2, but at position 2 there is a slope of 1
so it will slip by -2 positions, and end up at position 0
*rabbit 2 is at position 18*
*it will move by 3, but at position 21 there is a slope of 0*
*so it will slip by 0 positions, and end up at position 21*
*We have a potential winner...*
rabbit 3 is at position 11
it will move by 1, but at position 12 there is a slope of -1
so it will slip by 1 positions, and end up at position 13
So yeah :) that's basically my question (all this text for a simple question like that lol)
If you've managed to get to the end of my post then any guidance on my code would be appreciated too :)

I'm not going to read that long post. As suggested, produce an SSCCE
and paste in the exact, complete error message, and indicate clearly which line causes it.
I did notice this though:
Ok basically my question is that in the assignment there is an example output where the rabbit
is at position 21 but the array is only 20 in length and my program crashes if i go beyond the array length.Either you're misunderstanding something, or the assignment has a typo. If you have an array of length 20, then the indices are 0..19.
Maybe the instructor is calling index 0 position 1--separating Java's array impelementation details from
colloquial 1-based counting, so that the rabbit starts at "position 1" (index 0) goes through "position 20"
(index 19), and when he's done, he's "at postion 21"--i.e., past the finish line, off the end of the course, etc.
This won't correspond to any index in the array, but can still be considered a logical position in the race. "Oh, he's
at position 21. He's done. There's nothing more to do with the array, as it has no slot corresponding to
this 'done' position."
That's pure speculation on my part. You'll have to ask your instructor or figure out for yourself what's going on.

A few questions about Arrays and Array Methods.

I have 2 dimentional arrays in a number of classes, and I wish to pass them about as variables, however, I can only seem to send int[], rather than int[][]. Gives me some compile errors.
Another thing. How do i get the length of an array?
I've tried: getLength(object), but it's a 2d array (int[][]), and It's having none of it. How do i get the length of a particular side?

An object like int[][] only has a single "length", and that is the length of the first dimension. This object is an array that contains arrays of int, and each of those arrays could have a different length. Your 2D array may happen to be rectangular but that isn't a requirement of Java. So you would have to write your own code to find the lengths of the sides. The first side would be theArray.length, the second side would be theArray[0].length, and like that.

Hi, i got some question about arrays.

My question is how do i auto increase the array size for theList[0] to store the over time if the user enter more than 1 employee.
static void showPayInfo(int num1 , int num2)
 for(int coloum = 1 ; coloum <= num2 ; coloum++)
 System.out.print("Enter employee's over time $: ");
 ot = CspInput.readDouble();
 Double = ot;
 getDouble(Double);
static double ot , Double;
 static void getDouble(double Double)
 double[] theList = new double[2];
 theList[0] = ot;
 public static void main(String[] args)
 int a;
 System.out.print("How many employees : " );
 a = CspInput.readInt();
 showPayInfo(1,a);
 }

how to create the list?
import java.util.ArrayList;
class testArrayList {
 public static void main(String[] args) {
 ArrayList<String> list1 = new ArrayList<String>();
 // Populate list
 for (int i = 0; i < 5; i++) {
 list1.add("List item " + i);
 // Show list
 for (int i = 0; i < list1.size(); i++) {
 System.out.println(list1.get(i));
}

Hopefully an easy question about arrays

hi there
is there any way of creating an array of objects that is of unspecified size at the time of creating and then add objects as and when they are read from a file?
longer explanation:
i am creating molecule visualization software. the molecule's structure is stored in a text file, ie each line has info on one atom ie 3d coords etc. i'm storing the molecule structure in an object (Molecule.java) which has an array (Structure[]) of atoms (Atom.java). obviously molecules can have any number of atoms in it and you don't know how many until you've gone through the whole file and counted. The only way i can think of doing it is to go through the whole file, coun the atoms, close the file, create the Molecule object with the structure array size of NoOfAtoms and then open the file again and add the atoms as i go through them again. however, i refuse to believe this is the most efficient way of doing it as i have to go throguh the same file twice which brings me back to my original question.
as i said i'm hopeing there is a simple answer
cheers

Use a Collection . Use a Vector, ArrayList or even a Hashtable. You do not need to define the size of these objects and can add and remove Objects from them whenever you want

A question about arrays. Please Help

Ok here is my question lets say i have a multie varible array such as
int[][] thisList = new int[3][64];And I have a number of other arrays that are single variable arrays, and which have data stored in them.
List1[64]
List2[64]
List3[64]is there a way i can store all these three list in the multie varible array?
for example i know i can do this, > Correct me if i am wrong
List1 = List2; where List1 one now contains all the elements that List2 has.
but is there a way i can
us the same format with a multie varible array, to store all three list in it.
such as thisList[1][] = List1; thisList[2][] = List2[]; Thanks

for example i know i can do this, > Correct me if i
am wrong
List1 = List2; where List1 one now
contains all the elements that List2 has.There will be one array. Both the List1 and List2 reference variables will point to that same array.
(By the way, convention in Java is for variables to start with lowercase.)
>
but is there a way i can
us the same format with a multie varible array, to
store all three list in it.
such as thisList[1][] = List1; thisList[2][] =
List2[];
You can do thisList[1] = List1 if thisList is an int[][] and List1 is an int[]. However, that will not copy any ints. It will just do the same as the above--cause the reference thisList[1] to point to the same array object as List1 does.
If you want to copy values from one array to another, use System.arraycopy.

Very simple and quick question about Arrays

Hi,
I have the following code to produce a student grades provessing system. I have got it to store data in the array, i just cant figure out how to add the integers from the row to produce a total. Thats all I want to do create a total from the 6 marks and add a percentage.
Any help would be greatly appreciated.
-------------CODE BELOW----------------------
import java.util.*;
public class newstudent1_2
public static void main (String[]args)
System.out.println ("-----------------------------------------------"); //Decorative border to make the welcome message stand out
System.out.println (" Welcome to Student Exam Mark Software 1.2"); //Simple welcome message
System.out.println ("-----------------------------------------------");
int [][] mark;
int total_mark;
int num_students;
int num_questions = 9;
Scanner kybd = new Scanner(System.in);
System.out.println("How many students?");
num_students =kybd.nextInt();
mark = new int[num_students][num_questions] ;
for (int i=0; i<num_students; i++)
System.out.println("Enter the Students ID");
String student_id;
student_id =kybd.next();
System.out.println("Student "+i);
for( int j=1; j<num_questions; j++)
System.out.println("Please enter a mark for question "+j);
mark[i][j]=kybd.nextInt();
System.out.print("id mark1 mark2 mark3 mark4 mark5 mark6 mark7 mark8");
//This section prints the array data into a table
System.out.println();
for (int i=0; i<num_students; i++)
for( int j=0; j<num_questions; j++)
System.out.print(mark[i][j]+"\t"); //the \t is used to add spaces inbetween the output table
System.out.println();
--------------END OF CODE---------------
Thanks.

I had to do this same sort of thing for a school assignment but i didnt use an array.
import java.text.DecimalFormat;
import TurtleGraphics.KeyboardReader;
public class grade_avg
 public static void main(String[] args)
 int grade, total = 0, count = 0;
 double avg = 0.0;
 KeyboardReader reader = new KeyboardReader();
 DecimalFormat df = new DecimalFormat("0.00");
 for (;;)
 grade = reader.readInt("Please enter a grade: ");
 if (grade > 0)
 total = total + grade;
 count ++;
 if (grade == 0)
 avg = total / count;
 System.out.println("The average is: " + df.format(avg));
 System.exit(0);
}output looks like:
Please enter a grade: 100
Please enter a grade: 50
Please enter a grade: 0
The average is: 75.00

Hello and a question about Arrays

Hello! I am a student working towards a CIS degree, I'm only in my second term, so I have a long way to go still. Next term (starts in November) I'll be starting my first language (Java) so I figured this is a good spot to register and get acquainted with all of you.
Anyway, right now I'm in a programming logic and design class. In this class we use Pseudocode to get the basic constructs of programming down without doing anything language specific. I just read the chapter that introduces Arrays and had a difficult time following it. Could any of you take a minute and give me your definition of what exactly an array is and how it works? Or maybe point me to a link that might help me? I've got the 'jist' of it, but the book jumps right into algorithms using arrays without much explaination as to what they are.
Thanks for any response and for helping a programming "n00b".
-Rawhide

>
Hello! I am a student working towards a CIS
CIS degree, I'm only in my second term, so I have a
long way to go still. Next term (starts in November)
I'll be starting my first language (Java) so I
figured this is a good spot to register and get
acquainted with all of you.
Anyway, right now I'm in a programming logic andThink of an array as a series of boxes. These boxes store data for three
elements. So you would have three boxes that store one element of data.
So 'this' array has a capacity of three. If you want something bigger,
you'd create a array with more boxes, say 10. Then your array has a capacity of 10.
To get to anything from a array, you either need to :
a) go through all the elements of the array
b) or actually know the element you want to retrieve.
The second case is simple enough, you usually just specify the element you want. For example the first element would be zero.(counting starts from zero). The last element would be 9 (10 -1).
The first case requires some knowledge of looping, you'd generally itterate from the first until the last element of the array, in each and every element that you are at, do the stuff you need to do. This will go on until the end of the array is reached.
for(int i=0; i<=arraylength;i++ ) {
do some stuff. like print out to the console.
I'm not giving you any specific java code because you didn't ask for any and you were doing a course that wasn't language specific. So I figured that may be a simpler explanation(was it?) was in order.
Let me know if you need clarification.
and design class. In this class we use Pseudocode to
get the basic constructs of programming down without
doing anything language specific. I just read the
chapter that introduces Arrays and had a difficult
time following it. Could any of you take a minute
and give me your definition of what exactly an array
is and how it works? Or maybe point me to a link that
might help me? I've got the 'jist' of it, but the
book jumps right into algorithms using arrays without
much explaination as to what they are.
Thanks for any response and for helping a programming
"n00b".
-Rawhide

Simple newbie question about arrays..

Hello all,
I have two arrays declared like so below the class header:
String Players[];
String Final[];
I have a method like the following:
public String[] CollectPlayers() {
Players[0] = new String(txtPlayer1.getString());
return Players;
I am calling this method like so
Final = CollectPlayers();
Basically not working, giving nullpointerexception, but I feel that I am fundamentally not understanding something, so here is what I want...
A method that returns an array and (ideally) use this method directly in creating a ChoiceGroup, like this...
optBull = new ChoiceGroup("Bully", ChoiceGroup.EXCLUSIVE, CollectPlayers(), arrImage);
Is this possible? Any ideas?
Thanks in advance
poncenby

A few points:
- You almost never need to call new String(String).
- You may want to create an ArrayList (dynamic array) and then call toArray(new Players[0]) if you need it to be a fixed array.
e.g.
final List players = new ArrayList();
public List collectPlayers(List players) {
 List finals = new ArrayList();
 for(int i=0;i<players.size();i++) {
 Player player = (Player) players.get(i);
 finals.add(players.getResult());
 return finals;
players.add(new Player("anne"));
players.add(new Player("bob"));
players.add(new Player("fred"));
List finals = collectPlayers(players);

Log4j question about closed appender error

Hi all,
In my company's project, we have used the log4j 1.1.3 for logging. Since in the project, there are a few applications. We have a common properties to state the log4j properties for AppSTDERR(console), AppLogFile and AppNTEventLog. And we also have a properties file for each application. In each proeprties file, we state a different path to the AppLogFile for different application. We use PropertyConfigurator.configure() to configure the properties and use Category.getRoot(). However, sometimes some application's log will log to another application log file. So we decide to change the application properties file like this:
log4j.category.AppXXX=DEBUG, AppXXXSTDERR, AppXXXLogFile
log4j.appender.AppXXXLogFile=org.apache.log4j.DailyRollingFileAppender
log4j.appender.AppXXXLogFile.File=C:\\xxx\\xxx.log
log4j.appender.AppXXXLogFile.layout=org.apache.log4j.PatternLayout
log4j.appender.AppXXXLogFile.layout.ConversionPattern=%d{ISO8601} [%-5p] [%t] %m%n
log4j.appender.AppXXXSTDERR: org.apache.log4j.ConsoleAppender
log4j.appender.AppXXXSTDERR.layout: org.apache.log4j.PatternLayout
log4j.appender.AppXXXSTDERR.layout.ConversionPattern: %d{ISO8601} [%-5p] [%t] - %m%n
We don't use Category.getRoot() and use Category.getInstance("AppXXX") instead. But we sometimes get these errors on console:
log4j:ERROR Attempted to append to closed appender named [AppSTDERR].
log4j:WARN Not allowed to write to a closed appender.
log4j:ERROR Attempted to append to closed appender named [AppLogFile].
log4j:WARN Not allowed to write to a closed appender.
We don't know what is the problem. We guess that some common programs will log common messages to AppLogFile and AppSTDERR but we do not open the AppLogFile and AppSTDERR in each application. Is that we have to use Category.getRoot() ?
Anybody help?
Raymond

Do you not need a DatePattern value for the DailyRollingFileAppender? DatePattern being the variable that determines WHEN the logs are rolled.
If not specified what is the default value? Could not setting this value result in strange behavior?
These are shots in the dark I know but we are having similar issues. I can't find any documentation on what the default value is of DatePattern if not specified and have no idea what happens if no value is set. At any rate we are going to supply a value for DatePattern and see if it fixes our problem, I'll post the resutls.

Question about array!

Is there any way to make external array, which could be used by more than one application or flash movie?

The simplest solution is often the best.
If you are only using arrays: use a text file.
Text files can be read into any application and you can use the [split] method with a delimiter to create an array
If you are using both arrays and objects: use JSON
JSON can handle primitive objects which can also be used in any environment beyond Flash
Both solutions involve creating a text file of some sorts. Load the text file with a URLLoader (flash) or as binary (any other) and parse the text as an array or JSON.
Why you dont want to add an 'External Array' to an SWF
In all situations you should consider maintainance and updating. If you create the array in an SWF file, all changes to the array (large or small) will involve you having to re-complie and re-upload the new SWF file. This will get VERY time consuming the larger the project scale. Using a text file is a lot less foot print on processing and file size.

Question about the programming of a legend

Hello everybody,
I have a question about the programming of a waveform's legend. I
already asked here in this forum about the legend programming (03)
months ago.
I went satisfied but I ve just noticed that this code
(See Code old_legend_test.llb with main.vi as main function) operates a
little different from my expectances.
Therefore I have a new question and I want to know if it
is possible by labview programming to plot and show, on a waveform
chart, a signal with activ plot superior to zero (0) without to be
obliged to plot and show a signal with activ plot equal to zero (0) or
inferior to the desired activ plot.
I give you an example
of what I m meaning. I have by example 4 signals (Signal 0, 1, 2 and 3)
and each signal corresponds respectively to a channel (Chan1, Chan2,
Chan3, Chan4). I want to control the legend (activ plot, plot name and
plot color) programmatically. Is it possible with labview to plot signal
1 or 2 or 3 or (1, 3) or (2,3) or (1,2,3) or other possible combination
without to active the signal with the corresponding activ plot zero
(0)?
Let see the labview attached data
(new_legend_test.llb with main.vi as main function). When I try to
control the input selected values again I get them back but I don't
understand why they have no effect on the legend of my waveform chart.
Could somebody explain me what I m doing wrong or show me how to get a
correct legend with desired plots? Thank by advance for your assistance.
N.B.
The
both attached data are saved with labview 2009.
Sincerly,PrinceJack
Attachments:
old_legend_test.llb ‏65 KB
new_legend_test.llb ‏65 KB

Hi
princejack,
Thanks for
posting on National Instruments forum.
The behavior
you have is completely normal. You can control the number of row displayed in
the legend and this rows are linked to the data you send to your graph. Thus,
if you have 3 arrays of data, let say chan1, chan2 and chan3, you can choose
which data you want to display in your graph using the property node (Active
plot and visible). But for the legend as you send 3 plots there is an array of
the plot name [chan1, chan2, chan3] and you can display 0, 1, 2 or 3 rows of
this array but you cannot control the order in this array! So, to be able to
change this array you have to only send data you need to you graph. I'm not
sure my explanations are clear so I have implemented a simple example doing
that.
Benjamin R.
R&D Software Development Manager
http://www.fluigent.com/
Attachments:
GraphLegend.vi ‏85 KB

Question about IDashedAttributeValues interface

Hi to everyone, I have a question about IDashedAttributeValues interface. If I would like to apply custom dashes kDashedAttributeValuesBoss to a page item. I would expect that my code will look like this: InterfacePtr<IDashedAttributeValues> pAttribute(::CreateObject(kDashedAttributeValuesBoss)); pAttribute->SetPhase( nPhase ); pAttribute->SetCornerAdjustment((IDashedAttributeValues::CornerAdjustment)nCornerAdjust ment); pAttribute->SetValue( 0, nDash0 ); But InDesign crashes at SetValue code. I could understand InDesign. It is out of range. But, how to specify the length of value array or to add value into array? Thanks in advance, Alexander Staroverov Developer Engineer Comosoft GmbH

Thank you to all, I have found the answer in SDK samples: void SnpGraphicHelper::AddDashedValues(const K2Vector<PMReal>& dashAndGapValues) { IDataBase* db = fItemList.GetDataBase(); InterfacePtr<IDocument> theDocument(db, db->GetRootUID(), UseDefaultIID()); InterfacePtr<IUIDData> uidData(::CreateObject2<IUIDData>(kDashedAttributeValuesBoss)); ASSERT(uidData != nil); uidData->Set(::GetUIDRef(theDocument)); InterfacePtr<IDashedAttributeValues> dashedAttributeValues(uidData, UseDefaultIID()); if (dashedAttributeValues != nil && dashAndGapValues.size() > 0) { for (int32 i = 0; i < dashAndGapValues.size(); i++) { dashedAttributeValues->SetValue(i, dashAndGapValues[i]); } this->AddAnAttribute(dashedAttributeValues); } }

Questions about a MasterQuize program

Hi, everyone.
I got a in-class case study program like this in the class:
* This class stores/represents a question that has one of two
* answers: True or False.
* 
* It needs to track the following information:
* <ul>
* <li>Question text</li>
* <li>Correct answer</li>
* <li>The user's answer to the question</li>
* <li>Points value</li>
* <li>Category</li>
* <li>Difficulty rating</li>
* </ul>
// Our question should allow us to do the following:
// - Create question (constructor) -- may be overloaded
// - Print (display) question
// - Check client's answer for correctness
// - Get points value for question (0 or max)
// - Add "No-BS" grading option
// - Getting client's answer
// - Check to see if answered by client
public class TrueFalseQuestion
 // Class constants (to simplify changes to common values)
 public static final int MIN_DIFFICULTY_LEVEL = 1;
 public static final int MAX_DIFFICULTY_LEVEL = 5;
 public static final int DEFAULT_DIFFICULTY_LEVEL = 1;
 public static final int DEFAULT_POINT_VALUE = 1;
 public static final String DEFAULT_CATEGORY_VALUE = "none";
 // Class instance variables
 private String questionText;
 private String correctAnswer;
 private String userAnswer;
 private int pointsValue;
 private String category;
 private int difficultyLevel; // TODO: Set a range for difficulty levels
 * @param text The literal wording of this question
 * @param answer The correct answer for this question
 * @param pts The total points available for this question
 * @param ctgry Category keyword for this question
 * @param level The perceived/intended difficulty level of this question
 * 
 * Defines a TrueFalseQuestion object.
 public TrueFalseQuestion (String text, String answer, int pts, String ctgry, int level)
 // Set starting values for all instance variables
 questionText = text.trim();
 correctAnswer = answer.trim();
 userAnswer = null; // No user answer supplied yet
 if (pts >= 1) // We assume that every problem is worth at least 1 point
 pointsValue = pts;
 else
 pointsValue = DEFAULT_POINT_VALUE;
 category = ctgry.trim();
 if (level >= MIN_DIFFICULTY_LEVEL && level <= MAX_DIFFICULTY_LEVEL) // within range
 difficultyLevel = level;
 else
 difficultyLevel = DEFAULT_DIFFICULTY_LEVEL;
 // Simplified (overloaded) constructors
 * @param text The literal wording of this question
 * @param answer The correct answer for this question
 * @param pts The total points available for this question
 * 
 * Defines a TrueFalseQuestion with default values for category and difficulty level.
 public TrueFalseQuestion (String text, String answer, int pts)
 // Call pre-existing constructor with default category and difficulty
 this(text, answer, pts, DEFAULT_CATEGORY_VALUE, DEFAULT_DIFFICULTY_LEVEL);
 * @param text The literal wording of this question
 * @param answer The correct answer for this question
 * 
 * Defines a TrueFalseQuestion with the default point value, default category,
 * and default difficulty level.
 public TrueFalseQuestion (String text, String answer)
 // Call pre-existing constructor with default points, category and difficulty
 this(text, answer, DEFAULT_POINT_VALUE, DEFAULT_CATEGORY_VALUE,
 DEFAULT_DIFFICULTY_LEVEL);
 * @param text The literal wording of this question
 * @param answer The correct answer for this question
 * @param pts The total points available for this question
 * @param ctgry Category keyword for this question
 * 
 * Defines a TrueFalseQuestion with the default difficulty level.
 public TrueFalseQuestion (String text, String answer, int pts, String ctgry)
 // Call pre-existing constructor with default points, category and difficulty
 this(text, answer, pts, ctgry,
 DEFAULT_DIFFICULTY_LEVEL);
 * @param text The literal wording of this question
 * @param answer The correct answer for this question
 * @param ctgry Category keyword for this question
 * 
 * Defines a TrueFalseQuestion with the default point value and the default
 * difficulty level.
 public TrueFalseQuestion (String text, String answer, String ctgry)
 // Use default points and difficulty
 this(text, answer, DEFAULT_POINT_VALUE, ctgry, DEFAULT_DIFFICULTY_LEVEL);
 * @param text The literal wording of this question
 * @param answer The correct answer for this question
 * @param pts The total points available for this question
 * @param level The perceived/intended difficulty level of this question
 * 
 * Defines a TrueFalseQuestion with the default value for the question category.
 public TrueFalseQuestion (String text, String answer, int pts, int level)
 // Use default category
 this(text, answer, pts, DEFAULT_CATEGORY_VALUE, level);
 // Clients can invoke this method to retrieve the text of the current question.
 // We chose to return the text instead of printing it; this allows the client
 // to decide how it should be presented (via a GUI, over a network, etc.)
 public String getQuestion ()
 return questionText;
 // This method allows the client to store the user's answer inside the
 // TrueFalseQuestion object for easy comparison
 public void submitAnswer (String ans)
 userAnswer = ans;
 // This method reports whether the submitted answer matches the correct answer
 public boolean answerIsCorrect(String userAns) // This version does all the work
 if (userAns == null) // No response from user (yet)
 return false;
 else
 // Normalize and compare answers
 char key = normalize(correctAnswer); // Get 't' or 'f'
 char ans = normalize(userAns); // Get 't' or 'f'
 return (key == ans);
 public boolean answerIsCorrect ()
 return answerIsCorrect(userAnswer); // Call previously-defined version
 public int getPointsValue()
 return pointsValue;
 // Return the points awarded for the user's answer. This method does
 // NOT support partial credit; answers are either correct or incorrect.
 // If the "No-BS" option is selected, blank (unanswered) questions receive
 // 1 point automatically; otherwise, the score will be either 0 or the
 // question's normal points value.
 public int getPointsEarned(boolean useNoBSRule)
System.out.println("useNoBS: " + useNoBSRule + "\tuserAnswer: " + userAnswer + "\tcorrectAnswer: " + correctAnswer);
 if (useNoBSRule && (userAnswer == null))
 return 1;
 else if (userAnswer == null)
 return 0; // Without "No-BS", treat blank problems as incorrect
 if (answerIsCorrect() == false)
 return 0;
 else
 return pointsValue;
 // This method returns true if the user has submitted an answer
 // for this question (regardless of whether that answer is correct)
 public boolean hasBeenAnswered ()
 return (userAnswer != null);
 // Private helper method to convert all answers to single lowercase
 // letters (in this case, 't' for TRUE and 'f' for FALSE)
 private char normalize (String input)
 if (input != null)
 input = input.trim(); // Remove leading whitespace
 input = input.toLowerCase();
 return input.charAt(0);
 else
 return ' ';
import java.util.*;
* This class represents a complete test or quiz.
* Data stored:
* - List of questions
* - Total score earned
* - Total score possible
* - Name/title of test
* - Instructions
* - Category/class assignment
* - Student (test-taker) name
* - Date test is/was taken
* - Time started
* - Time completed
* - Maximum time allotted
* - (List of) Maximum attempts per question
* - List of attempts per question
* - List of difficulty ratings per question
* - Assignment weight
* Methods:
* - Constructor
* - Add question
* - Display question
* - Display test
* - Display instructions
* - Generate random exam
* - Take/administer test
* - Get score
* STUFF TO DO:
* - Add time/date restrictions
* - Add network access restrictions
* - Add other restrictions/allowances?
* @author (your name)
* @version (a version number or a date)
public class Test
 // Class constant
 public static final int MAX_NUMBER_OF_QUESTIONS = 10;
 // Class instance variables
 private String testName;
 private int scoreEarned; // What the student earned on the exam
 private int scorePossible; // Total point values of all questions
 private String instructions; // Exam header text
 private ArrayList<TrueFalseQuestion> questions; // Create inside constructor
 // Methods
 public Test (String name, String instr)
 testName = name;
 scoreEarned = 0;
 scorePossible = 0;
 instructions = instr;
 questions = new ArrayList<TrueFalseQuestion>(); //[MAX_NUMBER_OF_QUESTIONS];
 public String getInstructions()
 return instructions;
 public int getScore()
 return scoreEarned;
 public void addQuestion (TrueFalseQuestion q)
 scorePossible += q.getPointsValue();
 questions.add(q); // Automatically append question to end of test
 public String displayQuestion (int position)
 if (position < questions.size())
 return (position+1) + ". " + questions.get(position).getQuestion();
 else
 return null;
 public String displayTest ()
 String result = "";
 for (int i = 0; i < questions.size(); i++)
 result += (i+1) + ". (";
 TrueFalseQuestion t = questions.get(i);
 result += t.getPointsValue();
 result += " points)\n\n" + displayQuestion(i);
 result += "\n\n";
 return result;
 // Get test length (number of questions)
 public int length ()
 return questions.size();
 // Submit answer to a specific question
 public boolean answer(int number, String a)
 // Question numbers run from 0-(max-1) -- THIS WAS AN OFF-BY-ONE ERROR AT FIRST
 if (number >= 0 && number < questions.size())
 TrueFalseQuestion t = questions.get(number);
 t.submitAnswer(a);
 return true; // Question was answered
 else
 return false; // Unable to answer (nonexistent) question
 // Score exam
 public void scoreExam (boolean useNoBS)
 scoreEarned = 0;
 for (int i = 0; i < questions.size(); i++) // For each question in exam
 TrueFalseQuestion t = questions.get(i); // get current question
 scoreEarned += t.getPointsEarned(useNoBS);
}// Test harness for the Test and *Question classes
import java.util.*;
public class QuizDriver
 public static void main(String[] args)
 // Create a new Test object
 Test exam = new Test("Sample Exam", "Select the correct answer for each question");
 setUp(exam);
 Scanner sc = new Scanner(System.in);
 System.out.println(exam.getInstructions());
 // Administer exam
 for (int i = 0; i < exam.length(); i++)
 // Print out current question
 System.out.println(exam.displayQuestion(i));
 // Get user answer
 System.out.print("Your answer: ");
 String ans = sc.nextLine();
 if (ans.equals("")) // Handle blank responses for unanswered questions
 ans = null;
 exam.answer(i, ans);
 // Get exam results
 exam.scoreExam(true);
 System.out.println("Your final score was " + exam.getScore() + " points.");
 private static void setUp (Test t)
 TrueFalseQuestion x = new TrueFalseQuestion("The sky is blue.", "true", 2);
 t.addQuestion(x);
 x = new TrueFalseQuestion("The first FORTRAN compiler debuted in 1957", "true", 5);
 t.addQuestion(x);
 x = new TrueFalseQuestion("Spock was a Vulcan", "false", 3);
 t.addQuestion(x);
}This program is far from finishing.
I have many questions about this program, but let me ask this one first:
In the TrueFalseQeustion class, why are there so many constructors? What is the purpose of setting some of the variables to default values?
Thank you very much!!!
Edited by: Terry001 on Apr 16, 2008 10:02 AM

newark wrote:
Stop ignoring the error messages. You seem to think that an error message means you're doing the assignment wrong. It's probably a simple fix. Post the exact error messages, as well as the code that corresponds to them. The error message will tell you exactly what line the problem occurs on, so you know right where to look.Hi,
After some modifications, the program now gives me the result the assignment wants when I run it. But I still have trouble with the MultipleChoiceQuestion class
Here is the complete program
QuizDriver class
// Test harness for the Test and *Question classes
import java.util.*;
public class QuizDriver
 public static void main(String[] args)
 // Create a new Test object
 Test exam = new Test("Sample Exam", "Select the correct answer for each question");
 setUp(exam);
 Scanner sc = new Scanner(System.in);
 System.out.println(exam.getInstructions());
 // Administer exam
 for (int i = 0; i < exam.length(); i++)
 // Print out current question
 System.out.println(exam.displayQuestion(i));
 // Get user answer
 System.out.print("Your answer: ");
 String ans = sc.nextLine();
 if (ans.equals("")) // Handle blank responses for unanswered questions
 ans = null;
 exam.answer(i, ans);
 // Get exam results
 exam.scoreExam(true);
 System.out.println("Your final score was " + exam.getScore() + " points.");
 private static void setUp (Test t)
 Question x;
 x = new TrueFalseQuestion("The sky is blue.", "true", 2);
 t.addQuestion(x);
 x = new TrueFalseQuestion("The first FORTRAN compiler debuted in 1957", "true", 5);
 t.addQuestion(x);
 x = new TrueFalseQuestion("Spock was a Vulcan", "false", 3);
 t.addQuestion(x);
 x = new MultipleChoiceQuestion("What is the color of the car\na.Red\nb.Green", "a. Red", 3);
 t.addQuestion(x);
 x = new MultipleChoiceQuestion("What is the name of this class\na.CSE110\nb.CSE114", "b, CSE114", 3);
 t.addQuestion(x);
}Test
public class Test
 // Class constant
 public static final int MAX_NUMBER_OF_QUESTIONS = 10;
 // Class instance variables
 private String testName;
 private int scoreEarned; // What the student earned on the exam
 private int scorePossible; // Total point values of all questions
 private String instructions; // Exam header text
 private ArrayList<Question> questions; // Create inside constructor
 // Methods
 public Test (String name, String instr)
 testName = name;
 scoreEarned = 0;
 scorePossible = 0;
 instructions = instr;
 questions = new ArrayList<Question>(); //[MAX_NUMBER_OF_QUESTIONS];
 public String getInstructions()
 return instructions;
 public int getScore()
 return scoreEarned;
 public void addQuestion (Question q)
 scorePossible += q.getPointsValue();
 questions.add(q); // Automatically append question to end of test
 public String displayQuestion (int position)
 if (position < questions.size())
 return (position+1) + ". " + questions.get(position).getQuestion();
 else
 return null;
 public String displayTest ()
 String result = "";
 for (int i = 0; i < questions.size(); i++)
 result += (i+1) + ". (";
 Question t = questions.get(i);
 result += t.getPointsValue();
 result += " points)\n\n" + displayQuestion(i);
 result += "\n\n";
 return result;
 // Get test length (number of questions)
 public int length ()
 return questions.size();
 // Submit answer to a specific question
 public boolean answer(int number, String a)
 // Question numbers run from 0-(max-1) -- THIS WAS AN OFF-BY-ONE ERROR AT FIRST
 if (number >= 0 && number < questions.size())
 Question t = questions.get(number);
 t.submitAnswer(a);
 return true; // Question was answered
 else
 return false; // Unable to answer (nonexistent) question
 // Score exam
 public void scoreExam (boolean useNoBS)
 scoreEarned = 0;
 for (int i = 0; i < questions.size(); i++) // For each question in exam
 Question t = questions.get(i); // get current question
 scoreEarned += t.getPointsEarned(useNoBS);
}Question
public class Question
// Class constants
public static final int MIN_DIFFICULTY_LEVEL = 1;
public static final int MAX_DIFFICULTY_LEVEL = 5;
public static final int DEFAULT_DIFFICULTY_LEVEL = 1;
public static final int DEFAULT_POINT_VALUE = 1;
public static final String DEFAULT_CATEGORY_VALUE = "none";
// Class instance variables
protected String questionText;
protected String correctAnswer;
protected String userAnswer;
protected int pointsValue;
protected String category;
protected int difficultyLevel; //TODO: set a range for difficulty levels
// Constructors
public Question (String text, String answer, int pts, String ctgry, int level)
 questionText = text.trim();
 correctAnswer = answer.trim();
 userAnswer = null;
 if (pts >= 1)
 pointsValue = pts;
 else
 pointsValue = DEFAULT_POINT_VALUE;
 category = ctgry.trim();
 if (level >= MIN_DIFFICULTY_LEVEL && level <= MAX_DIFFICULTY_LEVEL)
 difficultyLevel = level;
 else
 difficultyLevel = DEFAULT_DIFFICULTY_LEVEL;
 // Overloaded (simplied) constructors
 public Question (String text, String answer, int pts)
 this(text, answer, pts, DEFAULT_CATEGORY_VALUE, DEFAULT_DIFFICULTY_LEVEL);
 public Question (String text, String answer, int pts, String ctgry)
 this(text, answer, pts, ctgry, DEFAULT_DIFFICULTY_LEVEL);
 public Question (String text, String answer, String ctgry)
 this(text, answer, DEFAULT_POINT_VALUE, ctgry, DEFAULT_DIFFICULTY_LEVEL);
 public Question (String text, String answer, int pts, int level)
 this(text, answer, pts, DEFAULT_CATEGORY_VALUE, level);
 // Methods
 public String getQuestion ()
 return questionText;
 // Use this method to store user answers
 public void submitAnswer (String ans)
 userAnswer = ans;
 public boolean answerIsCorrect (String userAns)
 if (userAns == null)
 return false;
 else
 // Normalize and compare answers
 char key = normalize (correctAnswer); //Get the first letter of an answer
 char ans = normalize (userAns); //Get the first letter of an answer
 return (key == ans);
 public boolean answerIsCorrect ()// Why do we need two answerisCorrect() methods?
 return answerIsCorrect (userAnswer);
 public int getPointsValue ()
 return pointsValue;
 public int getPointsEarned (boolean userNoBSRule)
 System.out.println ("useNoBS: " + userNoBSRule + "\tuseAnswer: " + userAnswer + "\tcorrectAnswer: " + correctAnswer);
 if (userNoBSRule && (userAnswer == null))
 return 1;
 else if (userAnswer == null)
 return 0;
 if (answerIsCorrect() == false)
 return 0;
 else
 return pointsValue;
 public String getCorrectAnswer ()
 return correctAnswer;
 public boolean hasBeenAnswered ()
 return (userAnswer != null);
 private char normalize (String input)
 if (input != null)
 input = input.trim();
 input = input.toLowerCase();
 return input.charAt(0);
 else
 return ' ';
 TrueFalseQuestion
public class TrueFalseQuestion extends Question
public TrueFalseQuestion (String text, String answer, int pts, String ctgry, int level)
 super(text, answer, pts, ctgry, level);
 public TrueFalseQuestion (String text, String answer, int pts)
 super(text, answer, pts, DEFAULT_CATEGORY_VALUE, DEFAULT_DIFFICULTY_LEVEL);
 public TrueFalseQuestion (String text, String answer, int pts, String ctgry)
 super(text, answer, pts, ctgry, DEFAULT_DIFFICULTY_LEVEL);
 public TrueFalseQuestion (String text, String answer, String ctgry)
 super(text, answer, DEFAULT_POINT_VALUE, ctgry, DEFAULT_DIFFICULTY_LEVEL);
 public TrueFalseQuestion (String text, String answer, int pts, int level)
 super(text, answer, pts, DEFAULT_CATEGORY_VALUE, level);
 // Methods
 public String[] getPossibleAnswerChoice ()
 String[] possibleAnswerChoice = {"true", "false"};
 return possibleAnswerChoice;
} MultipleChoiceQuestion
public class MultipleChoiceQuestion extends Question
 public MultipleChoiceQuestion (String text, String answer, int pts, String ctgry, int level)
 super(text, answer, pts, ctgry, level);
 public MultipleChoiceQuestion (String text, String answer, int pts)
 super(text, answer, pts, DEFAULT_CATEGORY_VALUE, DEFAULT_DIFFICULTY_LEVEL);
 public MultipleChoiceQuestion (String text, String answer, int pts, String ctgry)
 super(text, answer, pts, ctgry, DEFAULT_DIFFICULTY_LEVEL);
 public MultipleChoiceQuestion (String text, String answer, String ctgry)
 super(text, answer, DEFAULT_POINT_VALUE, ctgry, DEFAULT_DIFFICULTY_LEVEL);
 public MultipleChoiceQuestion (String text, String answer, int pts, int level)
 super(text, answer, pts, DEFAULT_CATEGORY_VALUE, level);
 // Methods
 String possibleAnswers;
 public String getPossibleAnswers ()
 return possibleAnswers;
 public void addAnswerChoice (String answerChoice)
 String ansChoice = answerChoice;
 questionText += "\nansChoice";
 possibleAnswers = answerChoice;
 public void printAnswerChoice ()
 System.out.println (questionText);
} I don't understand why the assignment wants me to build a method in the MultpleChoiceQuestion class to store the potential answer choices, I can make the program display the potential answer choices by including them in the questionText as following in the QuizDriver class
Question x;
x = new MultipleChoiceQuestion("What is the color of the car\na.Red\nb.Green", "a. Red", 3);
t.addQuestion(x); I don't know how to allow the client to construct the list of answer choices one at a time(add one potential answer choice by calling the addAsnwerChoices() method once)
Here are a few original sentences of my assignment which describe what I should do with the MultipleChoiceQuestion class
Using TrueFalseQuestion as a model, develop a new MultipleChoiceQuestion class that can be used to represent a problem where the user must select one of several answer choices (e.g., "Select answer (a), (b), (c), or (d)."). This new question type should have all of the same externally-visible functionality as TrueFalseQuestion, except that it must:
maintain a list of potential answer choices
provide a method that allows the client to construct the list of answer choices one at a time (i.e., the client should be able to call an addAnswerChoice() method to pass a new answer option to the MultipleChoiceQuestion.)
display (as part of the question text) the list of answer choices with appropriate letters ("abcd" instead of "0123") I don't understand what these sentences mean.
1. "Maintain a list of potential answer choices"-- this reminds me of the getPossibleAnswerChoice() method in the TrueFalseQuestion class
public String[] getPossibleAnswerChoice ()
 String[] possibleAnswerChoice = {"true", "false"};
 return possibleAnswerChoice;
 }I wonder that if the potential answer choices I have to store in the MultipleChoiceQuestion class are only letters "a", "b", "c", "d", etc, or include the answer text coming after the letters(eg. a.Red, b.Green)
2. "provide a method that allows the client to construct the list of answer choices one at a time". How do I achieve the functionality "one at a time"? Do I need to pass the input of the client (a potential answer choice) to the variable of the method which stores the list of potential answers?
3. "display (as part of the question text) the list of answer choices with appropriate letters". My question here is that: When the client type in one possible answer, should I append it to the variable questionText? (So I use the questionText variable in the methods of the first and second steps)
Thank you very much for your nice help!
Edited by: Terry001 on Apr 21, 2008 8:01 AM

Question about array append

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