Java concepts! Need help please!
hi,
im new to java, just started learning, im stuck on this last question in my assignment:
Could anyone please help with answer:
"Describe the followion OO programming concepts, explaining how they can be used to improve the writing and maintenance of software programs:
Classes
Objects
Inheritence
Overloading
Overriding
Interfaces"
its worth 25 marks of the assignment.
all help is appreciated
Thanks
Well, I suggest doing a search via google (the Internet has quite a bit of computer-related information available on it), or consulting more books. Go to your local public library or university library if you have one. You'll not learn much by copying down answers posted here.
Lee
Similar Messages
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I'm new to java and need help please
I have an assignment involves modifying a previous assignment. the code for the previous assigment is shown below.(it was required to be done as an applet this assigment can be an application or an applet) I'm trying to modify this code to read a text file (items.txt) that looks like this:
item # description price(this line does not appear in the text file)
001 shaving cream 400.00
999 razors 30.00
I need to load the item# and price from the text file into arrays(I have no clue how to use multi-dimensional arrays in java and would prefer not to)
I need to search the arrays based on the values entered by the user (item # and quantity) calculate the total for that item then create a new text file which has each line item for that order in the form:
item# quant price per item total(price per item*quant entered)
also also I need to be able to display the four items listed above after each loop as well as all the previous item number and quantities they selected until they indicate they don't want to select anymore.
I've been working on this for days and it seems like nothing I try works. My major problems are:
1. I have no idea how to read the text file and load those 2 items into their respective arrays
2. I can't seem to create a textfile that looks like text for the output file.
code]
import java.io.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.text.*;
import java.util.Locale;
public class arraySelection
extends JApplet {
//Initialize the applet
private Container getContentPane=null;
public void init() {
String string_item, string_quantity;
String output = "";
String description= "";
int counter= 0;
int itemNumber= 0;
double quantity = 0 ;
double tax_rate=.07;
double total= 0, price= 0;
double tax, subtotal;
double Pretotal= 0;
double priceArray[] = {1, .5, 3.65, 0.02, 0.09};
String descriptionArray[] = {"salt", "pepper", "paprika", "garlic", "thyme"};
// create number format for currency in US dollar format
NumberFormat moneyFormat = NumberFormat.getCurrencyInstance( Locale.US );
//format to have the total with two digits precision
DecimalFormat twoDigits = new DecimalFormat("0.00");
//Jtextarea to display results
JTextArea outputArea = new JTextArea ();
// get applet's content pane
Container container = getContentPane ();
//attach output area to container
container.add(outputArea);
//set the first row of text for the output area
output += "Invoice\nItem#\tDescription\tQuant@Price\t Line Total" + "\n";
do //begin loop structure obtain input from user
// obtain item number from user
string_item = JOptionPane.showInputDialog(
"Please enter an item number 1, 2, 3, 4, or 5:");
//obtain quantity of each item that user enter
string_quantity = JOptionPane.showInputDialog("Enter the quantity:");
// convert numbers from type String to Integer or Double
itemNumber = Integer.parseInt(string_item);
quantity = Double.parseDouble(string_quantity);
switch (itemNumber) {//Determine input from user to assign price and description
case 10: // user input item =10
price = priceArray[0];
description = descriptionArray[0];
break;
case 20: // user input item =20
price = priceArray [1];
description = descriptionArray[1];
break;
case 30: //user input item =30
price=priceArray[2];
description = descriptionArray[2];
break;
case 40: //user input item =40
price=priceArray[3];
description = descriptionArray[3];
break;
case 50: //user input item =50
price=priceArray[4];
description = descriptionArray[4];
break;
default: // user input item is not on the list
output += "Invalid value entered"+ "\n";
price=0;
description= "";
//Calculates the total for each item number and stores it in subtotal
subtotal = price * quantity;
//display input from user
output += itemNumber + "\t" + description + "\t\t"+ quantity + "@" +
moneyFormat.format( price) + "\t" + moneyFormat.format( subtotal) + "\n";
//accumulates the overall subtotal for all items
Pretotal = Pretotal + subtotal;
//verifies that the user wants to stop entering data
string_item = JOptionPane.showInputDialog(" Enter a positive integer to continue or 0 to stop. ");
itemNumber = Integer.parseInt(string_item);
// loop termination condition if user's input is 0 .It will end the loop
} while ( itemNumber!= 0);
tax = Pretotal * tax_rate; // calculate tax amount
total = Pretotal + tax; //calculate total = subtotal + tax
//appends data regarding the subtotal, tax, and total to the output area
output += "\n" + "Order Subtotal" + "\t" + moneyFormat.format( Pretotal) +
"\n" + "Tax" + "\t\t" + twoDigits.format( tax ) + "\n" + "Order Total" +
"\t\t" + moneyFormat.format( total );
//attaches the data in the output variable to the output area
outputArea.setText( output );
} //end init
}// end applet Invoice
Any help or sugestions would be greatly appreaciated. I've been working on this for over a week and everything I try goes nowhere.item # description price(this
line does not appear in the text file)
001 shaving cream 400.00
999 razors 30.00
I need to load the item# and price from the text file
into arrays(I have no clue how to use
multi-dimensional arrays in java and would prefer not
to)That's good, because you shouldn't use multidimensional arrays here. You should have a one-dimensional array (or java.util.List) of objects that encapsulate each line.
I've been working on this for days and it seems like
nothing I try works. My major problems are:
1. I have no idea how to read the text file and load
those 2 items into their respective arrays
2. I can't seem to create a textfile that looks like
text for the output file.The java.io package has file reading/writing classes.
Here's a tutorial:
http://java.sun.com/docs/books/tutorial/essential/io/index.html -
I'm new to java and need help please(repost)
I have an assignment involves modifying a previous assignment. the code for the previous assigment is shown below.(it was required to be done as an applet this assigment can be an application or an applet) I'm trying to modify this code to read a text file (items.txt) that looks like this:
item # description price(this line does not appear in the text file)
001 shaving cream 400.00
999 razors 30.00
I need to load the item# and price from the text file into arrays(I have no clue how to use multi-dimensional arrays in java and would prefer not to)
I need to search the arrays based on the values entered by the user (item # and quantity) calculate the total for that item then create a new text file which has each line item for that order in the form:
item# quant price per item total(price per item*quant entered)
also also I need to be able to display the four items listed above after each loop as well as all the previous item number and quantities they selected until they indicate they don't want to select anymore.
I've been working on this for days and it seems like nothing I try works. My major problems are:
1. I have no idea how to read the text file and load those 2 items into their respective arrays
2. I can't seem to create a textfile that looks like text for the output file.
import java.io.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.text.*;
import java.util.Locale;
public class arraySelection
extends JApplet {
//Initialize the applet
private Container getContentPane=null;
public void init() {
String string_item, string_quantity;
String output = "";
String description= "";
int counter= 0;
int itemNumber= 0;
double quantity = 0 ;
double tax_rate=.07;
double total= 0, price= 0;
double tax, subtotal;
double Pretotal= 0;
double priceArray[] = {1, .5, 3.65, 0.02, 0.09};
String descriptionArray[] = {"salt", "pepper", "paprika", "garlic", "thyme"};
// create number format for currency in US dollar format
NumberFormat moneyFormat = NumberFormat.getCurrencyInstance( Locale.US );
//format to have the total with two digits precision
DecimalFormat twoDigits = new DecimalFormat("0.00");
//Jtextarea to display results
JTextArea outputArea = new JTextArea ();
// get applet's content pane
Container container = getContentPane ();
//attach output area to container
container.add(outputArea);
//set the first row of text for the output area
output += "Invoice\nItem#\tDescription\tQuant@Price\t Line Total" + "\n";
do //begin loop structure obtain input from user
// obtain item number from user
string_item = JOptionPane.showInputDialog(
"Please enter an item number 1, 2, 3, 4, or 5:");
//obtain quantity of each item that user enter
string_quantity = JOptionPane.showInputDialog("Enter the quantity:");
// convert numbers from type String to Integer or Double
itemNumber = Integer.parseInt(string_item);
quantity = Double.parseDouble(string_quantity);
switch (itemNumber) {//Determine input from user to assign price and description
case 10: // user input item =10
price = priceArray[0];
description = descriptionArray[0];
break;
case 20: // user input item =20
price = priceArray [1];
description = descriptionArray[1];
break;
case 30: //user input item =30
price=priceArray[2];
description = descriptionArray[2];
break;
case 40: //user input item =40
price=priceArray[3];
description = descriptionArray[3];
break;
case 50: //user input item =50
price=priceArray[4];
description = descriptionArray[4];
break;
default: // user input item is not on the list
output += "Invalid value entered"+ "\n";
price=0;
description= "";
//Calculates the total for each item number and stores it in subtotal
subtotal = price * quantity;
//display input from user
output += itemNumber + "\t" + description + "\t\t"+ quantity + "@" +
moneyFormat.format( price) + "\t" + moneyFormat.format( subtotal) + "\n";
//accumulates the overall subtotal for all items
Pretotal = Pretotal + subtotal;
//verifies that the user wants to stop entering data
string_item = JOptionPane.showInputDialog(" Enter a positive integer to continue or 0 to stop. ");
itemNumber = Integer.parseInt(string_item);
// loop termination condition if user's input is 0 .It will end the loop
} while ( itemNumber!= 0);
tax = Pretotal * tax_rate; // calculate tax amount
total = Pretotal + tax; //calculate total = subtotal + tax
//appends data regarding the subtotal, tax, and total to the output area
output += "\n" + "Order Subtotal" + "\t" + moneyFormat.format( Pretotal) +
"\n" + "Tax" + "\t\t" + twoDigits.format( tax ) + "\n" + "Order Total" +
"\t\t" + moneyFormat.format( total );
//attaches the data in the output variable to the output area
outputArea.setText( output );
} //end init
}// end applet InvoiceAny help or sugestions would be greatly appreaciated. I've been working on this for over a week and everything I try goes nowhere.First answer: You shouldn't ask multiple questions in the same thread. Ask a specific question, with an appropriate subject line (optionally, assign the number of Dukes you are willing to give for the help). When question #1 is answered and question #2 arises, it's time for a new thread (don't forget to give out Dukes before moving on).
Second answer: I think you need a Transfer Object (http://java.sun.com/blueprints/patterns/TransferObject.html). It's whole purpose is to hold/transfer instance data where it is needed. Create a class something like this:
public class ItemTO
private String _number;
private String _description;
private double _price;
public ItemTO( String number, String description, double price )
_number = number;
_description = description;
_price = price
// Getter/Setter methods go here
}then, in the code where you read in the file do something like this:
BufferedReader input = null;
try
input = new BufferedReader( new FileReader( "c:\\a.txt" ) );
List items = new ArrayList();
String line;
String itemNumber;
String itemDescription;
double itemPrice;
while ( (line = input.readLine() ) != null )
System.out.println( line );
itemNumber = // Parse it from line
itemDescription // Parse it from line
itemPrice = // Parse it from line
items.add( new ItemTO( itemNumber, itemDescription, itemPrice ) );
catch ( FileNotFoundException fnfe )
fnfe.printStackTrace();
catch ( IOException ioe )
ioe.printStackTrace();
finally
try
if ( input != null )
input.close();
catch ( Exception e )
e.printStackTrace();
}As for how to parse the line of the file, I'll leave that to you for now. Are the three values delimited with any special characters?
jbisotti -
NO clue about JAVA but need help please
I am cleaning up someone's else work who used to be employed here. I know ZIP about Java but am becoming more and more familiar with WAR files and deplying them with Jrun on an NT2K Server.So here is what I have. I have a deployed app from months ago. I have a new app to deploy. I did this successfully. I can access it, etc. But I am getting some SQL error.
Can anyone give me any idea what it could be? I have looked at my sqlcustomauthentication.java file and i have not anything to it. Why would something change on this when all I really did was re-deploy it.
Here is the error.
Thanks a TON!!
java.lang.NullPointerException:
at allaire.jrun.security.SQLCustomAuthentication.getName(SQLCustomAuthentication.java:76)
at jrun__members2ejspc._jspService(jrun__members2ejspc.java:62)
at allaire.jrun.jsp.HttpJSPServlet.service(HttpJSPServlet.java:39)
at allaire.jrun.jsp.JSPServlet.service(JSPServlet.java:228)
at allaire.jrun.jsp.JSPServlet.service(JSPServlet.java:196)
at allaire.jrun.servlet.JRunSE.service(JRunSE.java, Compiled Code)
at allaire.jrun.session.JRunSessionService.service(JRunSessionService.java, Compiled Code)
at allaire.jrun.servlet.JRunSE.runServlet(JRunSE.java, Compiled Code)
at allaire.jrun.servlet.JRunRequestDispatcher.forward(JRunRequestDispatcher.java, Compiled Code)
at allaire.jrun.servlet.JRunSE.service(JRunSE.java, Compiled Code)
at allaire.jrun.servlet.JRunSE.service(JRunSE.java, Compiled Code)
at allaire.jrun.servlet.JvmContext.dispatch(JvmContext.java, Compiled Code)
at allaire.jrun.jrpp.ProxyEndpoint.run(ProxyEndpoint.java, Compiled Code)
at allaire.jrun.ThreadPool.run(ThreadPool.java, Compiled Code)
at allaire.jrun.WorkerThread.run(WorkerThread.java, Compiled Code)It looks like maybe you are having a problem in the way you are accessing the authentication on your db. From the error message, I would say the name field needed to log in is never being set
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Java student needs help please.
I'm a new CS major, I'm having a hell of a time with a java project.
Write a program to read in a list of nonnegative integers and to ouput the largest integer, smallest interger, an the average of the integers. The end of the input is indicated by the user entering a negative sentinel value.
Any ideas would be greatly appreciatedBobsters wrote:
well...im sorry to have an attitude. Now...let's move on.
This is as far as i have gotten.
import java.util.*;
public class Project2_1
public static void(String[] args)
double largest, smallest, average;
System.out.println("Enter some nonnegative intergers.");
System.out.println("Enter a negative integer after you have");
System.out.println("entered the nonnegative integers.");Is that it? If you're too simple-minded to work out anything more than that, please don't take CS courses. Best advice I can give you is, sign up again with another user name, wait about a week so we've forgotten you, then try again. And mind your manners next time round -
Image size and mime type.. non-java guy needs help
Image size, mime type.. non-java guy needs help
Im not at all familiar with java so this is really weird for me to work out. I?ve been doing it all day (and half of yesterday).
Im trying to write a custom clodFusion tag in java that gets the width, height, size and MIME types of a given file. I?ve been trying to get it to work on the command line first. I can get the width and height but cant get the size and the MIME type.
Here is what I got
/*import com.allaire.cfx.*;*/
import java.awt.image.renderable.*;
import javax.media.jai.*;
import com.sun.media.jai.codec.*;
import java.io.*;
import java.util.*;
public class ImageInfo {
private RenderedOp image = null;
private RenderedOp result = null;
private int height = 0;
private int width = 0;
private String type = "";
private String size = "";
public void loadf(String file) throws IOException
file = "80by80.jpg";
FileSeekableStream fss = new FileSeekableStream(file);
image = JAI.create("stream", fss);
height = image.getHeight();
width = image.getWidth();
System.out.println(height + "\n");
System.out.println(width);
System.out.println(type);
public static void main(String[] args) throws IOException {
ImageInfo test = new ImageInfo();
test.loadf(args[0]);
can anyone please help me out to modify the above so I can also print the mime type and the file size to screen.
thanks for any helpany suggestions?
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The Oracle JRE is only a web plugin. If you need server-side Java, you'll have to use the Apple-supplied Java 6 runtime, or else the Oracle JDK (which is not a drop-in replacement for Apple's Java.) If your server application depends on Java 7, you'll most likely have to run it on another operating system.
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Hi there ajsupprt,
It sounds like you may need to update the version of Java installed on your computer. Take a look at the article below for more information.
Java updates available for OS X on August 28, 2013
http://support.apple.com/kb/ht5648
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How can I add a new Template to My Templates in Pages? I've read most of the discussions on the subject but it doesn't work for me. By the time I reach the Templates folder, I only see templates for Numbers and not for Pages. Need help, please. Thanks
Si vous avez utilisé la commande Save As Template depuis Pages, il y a forcément un dossier
iWork > Pages
contenant Templates > My Templates
comme il y a un dossier
iWork > Numbers
contenant Templates > My Templates
Depuis le Finder, tapez cmd + f
puis configurez la recherche comme sur cette recopie d'écran.
puis lancez la recherche.
Ainsi, vous allez trouver vos modèles personnalisés dans leur dossier.
Chez moi, il y en a une kyrielle en dehors des dossiers standards parce que je renomme wxcvb.template quasiment tous mes documents Pages et wxcvb.nmbtemplate à peu près tous mes documents Numbers.
Ainsi, quand je travaille sur un document, je ne suis pas ralenti par Autosave.
Désolé mais je ne répondrai plus avant demain.
Pour moi il est temps de dormir.
Yvan KOENIG (VALLAURIS, France) mercredi 23 janvier 2011 22:39:28
iMac 21”5, i7, 2.8 GHz, 4 Gbytes, 1 Tbytes, mac OS X 10.6.8 and 10.7.2
My iDisk is : <http://public.me.com/koenigyvan>
Please : Search for questions similar to your own before submitting them to the community -
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Contact iTunes
Contact iTunes -
Hi i need help please i been playing clash of clans over 13 months. And today o realise what someone using my game Centra. Someone playing on my game Clash of Clans. I been change my Apple ID password, email, but doesn't work. When I playing game I can see what someone else trying connecting to my game And I don't know what to do.So if you can help me please? I don't wanna lose my game.
Hello Vaidas Vaidas,
It sounds like you are noticing someone else is accessing your Clash of Clans data by playing the game and you have tried to reset your Apple ID password. If you are following the steps outlined in this article:
Apple ID: Changing your password
http://support.apple.com/kb/ht5624
What is preventing you from changing your password? Any error messages or prompts?
Thank you for using Apple Support Communities.
All the best,
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To turn off auto sync - launch iTunes and go to Edit>Preferences>Devices - check the box at the bottom that says - Prevent iPod, iPhones and iPads from syncing automatically. Click OK and then quit iTunes.
Connect your iDevice to your PC.
Launch iTunes,
Click on the device name on the left side of the iTunes Window.
Click on the Photos Tab in the iTunes window on the right.
Untick all of the photos or albums that you want to remove.
Click on Apply in the lower right corner of iTunes
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