String array length

Can any one tell me how to get the no. of rows and no. of columns in an string array.
ie if i have array like
1 2 3 4
4 5 6 5
7 8 9 6
in an a[][]. how to fine values ie row =3 and col = 4

Assuming that the array is a rectangle (all rows have the same number of columns) and that it's two dimensional, you can do this:
int row = a.length;
int col=a[0].length;
I think that works, try it

Similar Messages

Problems with string array, please help!

I have a String array floor[][], it has 20 rows and columns
After I do some statement to modify it, I print this array
out in JTextArea, why the output be like this?
null* null....
null null...
null null...
How to correct it?

a turtle graphics applet:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class TG extends JApplet implements ActionListener {
private int x, y;
private int pendown, command, movement;
String direction, output, temp;
JLabel l1;
JTextField tf1;
JTextArea ta1;
String floor[][] = new String[20][20];;
public void init()
    x = 0;
    y = 0;
    pendown = 0;
    direction = "r";
    Container c = getContentPane();
    c.setLayout( new FlowLayout() );
       l1 = new JLabel( "Please type a command:" );
       c.add( l1 );
       tf1 = new JTextField(20);
       tf1.addActionListener( this );
       c.add( tf1 );
       ta1 = new JTextArea(20,20);
       ta1.setEditable( false );
       c.add( ta1 );
public void actionPerformed( ActionEvent e )
       temp = tf1.getText();
       if( temp.length() > 1)
       command = Integer.parseInt(temp.substring(0,1));
       movement = Integer.parseInt(temp.substring(2,temp.length()));
       else
       command = Integer.parseInt(temp);
       switch(command)
            case 1:
            pendown=0;
            break;
            case 2:
            pendown=1;
            break;
            case 3:
            direct("r");
            break;
            case 4:
            direct("l");
            break;
            case 5:
           move(movement);
            break;
            case 6:
            print();
            break;
public void direct(String s)
     if(direction == "r" && s =="r")
        direction = "d";
     else if(direction == "r" && s =="l")
        direction = "u";
     else if(direction == "l" && s =="r")
        direction = "u";
     else if(direction == "l" && s =="l")
        direction = "d";
     else if(direction == "u" && s =="r")
        direction = "r";
     else if(direction == "u" && s =="l")
        direction = "l";
     else if(direction == "d" && s =="r")
        direction = "l";
     else if(direction == "d" && s =="l")
        direction = "r";
public void move(int movement)
     if(pendown == 1)
          if(direction == "u")
          for(int b=0;b<movement;b++)
               floor[x][y+b] = "*";
          else if(direction == "d")
          for(int b=0;b<movement;b++)
               floor[x][y-b] = "*";
          else if(direction == "l")
          for(int b=0;b<movement;b++)
               floor[x-b][y] = "*";
          else if(direction == "r")
          for(int b=0;b<movement;b++)
               floor[x+b][y] = "*";
      else if(pendown == 0)
           if(direction == "u")
          for(int b=0;b<movement;b++)
               floor[x][y+b] = "-";
          else if(direction == "d")
          for(int b=0;b<movement;b++)
               floor[x][y-b] = "-";
          else if(direction == "l")
          for(int b=0;b<movement;b++)
               floor[x-b][y] = "-";
          else if(direction == "r")
          for(int b=0;b<movement;b++)
               floor[x+b][y] = "-";
      public void print()
     for(int row=0;row<20;row++)
       for( int column=0;column<20;column++)
            output += floor[row][column];
            if(column == 19)
             output+="\n";
        ta1.setText(output);
}

Problems with string arrays

Previous task was:
Write a class "QuestionAnalyser" which has a method "turnAnswerToScore". This method takes a String parameter and returns an int. The int returned depends upon the parameter:
parameter score
"A" 1
"B" 2
"C" 3
other 0
Alright, here's the recent task:
Write another method "turnAnswersToScore". This method takes an array of Strings as a parameter, works out the numerical score for each array entry, and adds the scores up, returning the total.
That's my code:
class QuestionAnalyser{
public static int Score;
public String[] Answer;
public static void main(String[] args) {}
     public int turnAnswerToScore(String[] Answer)
for (int i = 0; i < Answer.length;i++) {
if (Answer.equals("A")) {
Score = Score + 1; }
else if (Answer[i].equals("B")) {
Score = Score + 2;}
else if (Answer[i].equals("C")) {
Score = Score + 3;}
else {
Score = Score + 0;}
return Score;
this is the error message I get:
The results of trying to compile your submission and run it against a set of test data was as follows:
----------Compilation output--------------------------------------
javac QATest2.java
QATest2.java:15: cannot resolve symbol
symbol : method turnAnswersToScore (java.lang.String[])
location: class QuestionAnalyser
if(qa.turnAnswersToScore(task)!=total){
^
What went wrong?
Suggestions would be greatly appreciated!

If I declare int score in the method i get this message
The results of trying to compile your submission and run it against a set of test data was as follows:
----------Compilation output--------------------------------------
javac QATest2.java
./QuestionAnalyser.java:20: variable score might not have been initialized
score++; }
^
./QuestionAnalyser.java:23: variable score might not have been initialized
score++;
^
./QuestionAnalyser.java:27: variable score might not have been initialized
score++;
^
./QuestionAnalyser.java:34: variable score might not have been initialized
return score;
^
4 errors
----------Sorry expected answer was-------------------------------
The method turnAnswersToScore is working OK - well done!
----------Your answer however was---------------------------------
Exception in thread "main" java.lang.NoClassDefFoundError: QuestionAnalyser
     at QATest2.main(QATest2.java:4)
This is the message I get from the submission page, but trying to compile it I get the same messages.
The code looks like this, then
class QuestionAnalyser{
String[] answer;
public static void main(String[] args) {}
     public int turnAnswersToScore(String[] answer)
int score;
for (int i = 0; i < answer.length; i++) {
if (answer.equals("A")) {
score++; }
else if (answer[i].equals("B")) {
score++;
score++; }
else if (answer[i].equals("C")) {
score++;
score++;
score++; }
else {}
return score;
When I leave 'public int score;' where it was before (right after the class declaration below the declaration of the string array) I get this but it compiles normally.
The results of trying to compile your submission and run it against a set of test data was as follows:
----------Compilation output--------------------------------------
javac QATest2.java
----------Sorry expected answer was-------------------------------
The method turnAnswersToScore is working OK - well done!
----------Your answer however was---------------------------------
wrong answer in turnAnswersToScore for
BDCAADDCA
Alright, even university students need to sleep :-)
Good night.

Remove null values from string array

Hi ,
I have a string array in a jsp page which I save some values inside. After I store the values I want to print only those who are not null. How can I do this? Is there a way to delete the null values?

Thank you but because I am new in programming what do you mean to use continue. Can you explain it a little bit further?<%
//go through the array to check all the values
for(int i=0; i<array.length();i++) {
//If array is null, nothing happen
if(array==null){
//leave here blank; instead use continue like:
//this will skip the statements next to it, and increments the value of i in for loop and continues to execute the body of for loop.
//The same will be repeated till the last iteration.
continue;
//If array not null, then print value in a new line
else{
out.print(array+"<br>"); //don't change the logic here
%>

How to add elements into java string array?

I open a file and want to put the contents in a string array. I tried as below.
String[] names;
s = new Scanner(new BufferedReader(new FileReader("outfile.txt")));
while (s.hasNext()) {
                String item = s.next();
                item.trim();
                email = item;
                names = email;
            }But I know that this is a wrong way of adding elements into my string array names []. How do I do it? Thanks.

Actually you cannot increase the size of a String array. But you can create a temp array with the lengt = lengthofarray+1 and use arraycopy method to copy all elements to new array, then you can assign the value of string at the end of the temp array
I would use this one:
String [] sArray = null;
s = new Scanner(new BufferedReader(new FileReader("outfile.txt")));
while (s.hasNext()) {
    String item = s.next();
    item.trim();
    email = item;
    sArray = addToStringArray(sArray, email);
* Method for increasing the size of a String Array with the given string.
* Given string will be added at the end of the String array.
* @param sArray String array to be increased. If null, an array will be returned with one element: String s
* @param s String to be added to the end of the array. If null, sArray will be returned.(No change)
* @return sArray increased with String s
public String[] addToStringArray (String[] sArray, String s){
     if (sArray == null){
          if (s!= null){
               String[] temp = {s};
               return temp;
          }else{
               return null;
     }else{
          if (s!= null){
               String[] temp = new String[sArray.length+1];
               System.arraycopy(sArray,0,temp,0,sArray.length);
               temp[temp.length-1] = s;
               return temp;
          }else{
               return sArray;
}Edited by: mimdalli on May 4, 2009 8:22 AM
Edited by: mimdalli on May 4, 2009 8:26 AM
Edited by: mimdalli on May 4, 2009 8:27 AM

Getting lenght of String array

Hi,
How can i find the lenght of a string array, i have used length method to calculate length of single string value,e.g
String value = "test"
int length = value.length()
Now i want to calculate length of a string array.e.g
String csv_values = "test,by,random"
String[] str = csv_values.split(",")
int lenght = str.length()
As you can see i want to calculate total number of entries in an array after i split it dynamically.
Currently it is giving me exception, "Unable to parse exception; Undefined method: length for class: [Ljava.lang.String]"
Thanks

This is a tricky one. An Array has a length property, unlike a String which has a length method.
So...
int length = str.length
Anthony Holloway
Please use the star ratings to help drive great content to the top of searches.

String Array Constant Addition

Is there an elegant way of marking the last element in a string array
constant? i.e. I take an Array constant, and add a simple string to it,
so that it becomes a String Array Constant. Now I add elements 1 and 2
and 3. But now I want to take element 3 out. If I just delete Element 3
contents from the string control, that is fine, but the # of Array
elements is still 3. It is just that the 3rd elelment is null. How can I
make the array length 2? Now I know that starting over is one option
(just creat a new array constant, and add the two elements) but what if
my array constant has 100 elements and I want to make it 99. I also
know that programatically I can remove these elelents, but I am taking
about in the programming of th
is constant. I must be over looking
something... Any ideas???
Sent via Deja.com http://www.deja.com/
Before you buy.

[email protected] wrote:
> Is there an elegant way of marking the last element in a string array
> constant? i.e. I take an Array constant, and add a simple string to it,
> so that it becomes a String Array Constant
Arrays must be all the same type. If the last element is a constant, all
elements are
> Now I add elements 1 and 2
> and 3. But now I want to take element 3 out. If I just delete Element 3
> contents from the string control, that is fine, but the # of Array
> elements is still 3. It is just that the 3rd elelment is null.
In a string, yes, Empty strings are essentially nulls.
> How can I
> make the array length 2? Now I know that starting over is one option
> (just creat a new array constant, and add the two elements) but what if
> my array cons
tant has 100 elements and I want to make it 99. I also
> know that programatically I can remove these elelents, but I am taking
> about in the programming of this constant. I must be over looking
> something... Any ideas???
This is one of my problems. It is easy to size an array up, but hard to size
down.
Of course you can resize at run time but the only way I know to do this
when editing is to start over.
Kevin Kent
Attachments:
Kevin.Kent.vcf ‏1 KB

Newbie trying to sort 2D string array

Dear all,
After read some book chapters, web sites including this, I still don't get the point.
If I have a file like,
1 aaa 213 0.9
3 cbb 514 0.1
2 abc 219 1.3
9 bbc 417 10.4
8 dee 887 2.1
9 bba 111 7.1
and I load into memory as a String[][]
here comes the problem, I sort by column 1 (aaa,...,bba) using an adaptation of the Quicksort algorithm for 2D arrays
* Sort for a 2D String array
* @param a an String 2D array
* @param column column to be sort
public static void sort(String[][] a, int column) throws Exception {
QuickSort(a, 0, a.length - 1, column);
/** Sort elements using QuickSort algorithm
static void QuickSort(String[][] a, int lo0, int hi0, int column) throws Exception {
int lo = lo0;
int hi = hi0;
int mid;
String mitad;
if ( hi0 > lo0) {
/* Arbitrarily establishing partition element as the midpoint of
* the array.
mid = ( lo0 + hi0 ) / 2 ;
mitad = a[mid][column];
// loop through the array until indices cross
while( lo <= hi ) {
/* find the first element that is greater than or equal to
* the partition element starting from the left Index.
while( ( lo < hi0 ) && ( a[lo][column].compareTo(mitad)<0))
++lo;
/* find an element that is smaller than or equal to
* the partition element starting from the right Index.
while( ( hi > lo0 ) && ( a[hi][column].compareTo(mitad)>0))
--hi;
// if the indexes have not crossed, swap
if( lo <= hi )
swap(a, lo, hi);
++lo;
--hi;
/* If the right index has not reached the left side of array
* must now sort the left partition.
if( lo0 < hi )
QuickSort( a, lo0, hi, column );
/* If the left index has not reached the right side of array
* must now sort the right partition.
if( lo < hi0 )
QuickSort( a, lo, hi0, column );
* swap 2D String column
private static void swap(String[][] array, int k1, int k2){
String[] temp = array[k1];
array[k1] = array[k2];
array[k2] = temp;
----- end of the code --------
if I call this from the main module like this
import MyUtil.*;
public class kaka
public static void main(String[] args) throws Exception
String[][]a = MyUtil.fileToArray("array.txt");
MyMatrix.printf(a);
System.out.println("");
MyMatrix.sort(a,1);
MyMatrix.printf(a);
System.out.println("");
MyMatrix.sort(a,3);
MyMatrix.printf(a);
for the first sorting I get
1 aaa 213 0.9
2 abc 219 1.3
9 bba 111 7.1
9 bbc 417 10.4
3 cbb 514 0.1
8 dee 887 2.1
(lexicographic)
but for the second one (column 3) I get
3 cbb 514 0.1
1 aaa 213 0.9
2 abc 219 1.3
9 bbc 417 10.4
8 dee 887 2.1
9 bba 111 7.1
this is not the order I want to apply to this sorting, I would like to create my own one. but or I can't or I don't know how to use a comparator on this case.
I don't know if I am rediscovering the wheel with my (Sort String[][], but I think that has be an easy way to sort arrays of arrays better than this one.
I've been trying to understand the Question of the week 106 (http://developer.java.sun.com/developer/qow/archive/106/) that sounds similar, and perfect for my case. But I don't know how to pass my arrays values to the class Fred().
Any help will be deeply appreciated
Thanks for your help and your attention
Pedro

public class StringArrayComparator implements Comparator {
int sortColumn = 0;
public int setSortColumn(c) { sortColumn = c; }
public int compareTo(Object o1, Object o2) {
    if (o1 == null && o2 == null)
      return 0;
    if (o1 == null)
      return -1;
    if (o2 == null)
      return 1;
    String[] s1 = (String[])o1;
    String[] s2 = (String[])o2;
    // I assume the elements at position sortColumn is
    // not null nor out of bounds.
    return s1[sortColumn].compareTo(s2[sortColumn]);
// Then you can use this to sort the 2D array:
Comparator comparator = new StringArrayComparator();
comparator.setSortColumn(0); // sort by first column
String[][] array = ...
Arrays.sort(array, comparator);I haven't tested the code, so there might be some compiler errors, or an error in the logic.

Converting vector to string array

How can I convert values in a vector into a string array?
Vector formsVector = new Vector();
while (rs.next())
{formsVector.add(rs.getString("forms"));}
String forms[] = (String[])formsVector.toArray();
I tried the above line but it did not work. Any input please?
Thanks

.... What is the difference between the two as
according to online help, both are same.
String forms[] = (String [])formsVector.toArray();
String forms[] = (String [])formsVector.toArray( new
String[0] );The difference lies in the type of the object returned from toArray. The first form you list, formsVector.toArray(), always returns an Object[]. In your example, you'll get a ClassCastException at runtime when you cast to String[].
The second form will try to use the array you pass in. If it's not big enough, it'll create a new one of the same type as that array. This is what's happening when passing a zero-length array into toArray.
My personal preference is to save an extra instantiation and build the array to the proper size to begin with:String forms[] = (String [])formsVector.toArray( new String[formsVector.size()] );

Number of repeated characters in string array

Hi,
I m trying to get number of repeated characters in string array. I couldnt figure out where am i doing mistake.
thank you,
For example: count({"alpha, beta,"}, 'a')
a is repeated 3
l is repeated 1 etc.
public class Test
public static int count(String[] stringArray, char c)
public String [] str = new String [2];
int count = 0;
str[0]
str[1]
for(int i = 0; i<str.length(); i++)
if (str.charAt(i)
count++;
return count;

There is a difference between a String and a String [].
A String [] is an array of String class objects:/* Traverse_Array_Of_Strings_1.java */
public class Traverse_Array_Of_Strings_1
public static void main(String [] argv)
    /* here is an array of Strings */
    String [] s = { "hello", "how", "are", "you" };
    int i, j;
    System.out.println("s.length = "+ s.length );
    for (i= 0; i < s.length; i++)
      System.out.println("s= <"+ s[i] +">");
      for (j= 0; j < s.length(); j++)
System.out.print(s[i].charAt(j) +", ");
System.out.println("\n-----");
}output:java> javac Traverse_Array_Of_Strings_1.java
java> java Traverse_Array_Of_Strings_1
s.length = 4
s= <hello>
h, e, l, l, o,
s= <how>
h, o, w,
s= <are>
a, r, e,
s= <you>
y, o, u,
Edited by: vim_no1 on Jul 15, 2010 7:43 AM

Help with a store function that takes string array

Hi All,
I have a function that takes in two string arrays, status_array, and gender_array. You can see the partial code below. Somehow if the value for the string array is null, the code doesn't execute properly. It should return all employees, but instead it returns nothing. Any thoughts? THANKS.
for iii in 1 .. status_array.count loop
v_a_list := v_a_list || '''' || status_array(iii) || ''',';
end loop;
v_a_list := substr(v_a_list, 1, length(trim(v_a_list)) - 1);
for iii in 1 .. gender_array.count loop
v_b_list := v_b_list || '''' || gender_array(iii) || ''',';
end loop;
v_b_list := substr(v_b_list, 1, length(trim(v_b_list)) - 1);
IF v_a_list IS NOT NULL and v_b_list IS NOT NULL THEN
v_sql_stmt := 'select distinct full_name from t_employee where status in (' || v_a_list || ') and gender in (' || v_b_list || ')';
ELSIF v_a_list IS NOT NULL and v_b_list IS NULL THEN
v_sql_stmt := 'select distinct full_name from t_employee where status in (' || v_a_list || ') ';
ELSIF v_a_list IS NULL and v_b_list is not null THEN
v_sql_stmt := 'select distinct full_name from t_employee where gender in (' || v_b_list || ')';
ELSE
v_sql_stmt := 'select distinct full_name from t_employee';
END IF;
OPEN v_fullname_list FOR v_sql_stmt;
RETURN v_fullname_list;

I'd first recommend trying to avoid the dynamic sql.
use an approach like
[http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:210612357425] or
[http://stackoverflow.com/questions/1625649/oracle-parameters-with-in-statement/1655743#1655743] or [http://stackoverflow.com/questions/1715978/how-to-use-an-oracle-associative-array-in-a-sql-query]
but if that isn't in scope, do a
dbms_output.putline(v_a_list) ;
dbms_output.putline(v_b_list) ;
dbms_output.putline(v_sql_stmt) ;around and see what it emits

Finding the no of occurences of a string in a string array

hi
I have a string array which contains different strings say
for eg date
[21/08/2008, 21/08/2008, 21/08/2008, 21/08/2008, 21/08/2008, 21/08/2008, 21/08/2008, 21/08/2008, 21/08/2008, 21/08/2008, 21/08/2008, 21/08/2008, 22/08/2008, 22/08/2008, 22/08/2008, 22/08/2008, 22/08/2008] etc.
for eg names
[coverage, search, search, combined-search, documentService, expand-term, id-mapping, citation, class, corporate-tree, document-update, coverage, coverage, search, search, combined-search, documentService, expand-term, id-mapping, citation, class, corporate-tree, document-update, coverage]
i need to find out the count of a particular date or name in the string array.
Also i will not be knowing what is the value that will be present in that string array.
the values are dynamic. please help to solve this.
thanks in advance
Mohan

In the same way use for date,names and other as required by you..sample code for nameimport java.io.*;
public class Test {
     public static void main(String args[]) throws Exception{
         int cnt=0;
               String name[]={"coverage","abc","def","coverage", "search", "search"};
          BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
          System.out.println("enter name");
          String rv=br.readLine();
     for(int i=0;i<name.length;i++){
          if(rv.equals(name)){
               cnt++;
System.out.println("Name occured "+cnt+" times");

Covert String Array to String

Hey,
I have this code that take a string
EX:
Straw? No, too stupid a fad, I put soot on warts
and takes out the "?" and "," and places a space in their spot, then tokenizes the string so now all the spaces are gone (right?) then places the tokenized string into and array. Now I want that array into a string.
Pretty much what I want to go from is
this:
Straw? No, too stupid a fad, I put soot on warts
to:
StrawNotoostupidafadIputsootonwarts
here is my code
import java.util.*;
public class TrivialApplication {
     public static void main(String args[])
          System.out.println( "Hello World!\n" );
          String hello = "Straw? No, too stupid a fad, I put soot on warts";
          hello = hello.replace('?',' ');
          hello = hello.replace(',',' ');
          StringTokenizer tokenizer = new StringTokenizer(hello);
          String[] array = new String[hello.length()];
          System.out.println(tokenizer.countTokens());
          System.out.println(hello.length());
          int count = tokenizer.countTokens();
          int x = 0;
          while(tokenizer.hasMoreTokens())
               array[x] = tokenizer.nextToken();
               x++;
}

Sweet thanks man here is the finished code. I took out the array because it was now not needed.
import java.util.*;
public class TrivialApplication {
     public static void main(String args[])
          System.out.println( "Hello World!\n" );
          String hello = "Straw? No, too stupid a fad, I put soot on warts";
          System.out.println(hello + "\n");
          hello = hello.replace('?',' ');
          hello = hello.replace(',',' ');
          StringTokenizer tokenizer = new StringTokenizer(hello);
          StringBuffer buffer = new StringBuffer();
          int count = tokenizer.countTokens();
          while(tokenizer.hasMoreTokens())
               buffer = buffer.append(tokenizer.nextToken());
          hello = buffer.toString();
          System.out.println("New String with changes \n");
          System.out.println(hello);
[\code]

Trying to setText on random JPanels via a String array?

My assignment is to create a bunch of JButtons, and randomly have an "X" appear on one, until it is clicked, and then it goes away and reappears on another random one. It does this ten times and displays the time it took to do so.
I've created all the JButtons, named b01 to b48 and put them in a gridLayout. That part works fine.
I created a String[] array with the 48 names of the JButtons in it, then I was thinking I could go this route...
Random r = new Random();
String random = panels[r.nextInt(panels.length)];
random.setText("X"); //This is where the program hangs up.I can replace the setText statement with a System.out.println statement, and it shows up on the console correctly...

Brandon,
Have a chook at my minesweeper game at http://forum.java.sun.com/thread.jspa?forumID=54&threadID=5248903 ... it uses a matrix of cells[rows][cols]... each Cell is a JPanel which contains a Button.
I think you'll end up with something like ...
// create an array of Buttons
Button buttons[] = Button[NUM_BUTTONS];
for (int i=0; i<NUM_BUTTONS; i++) {
buttons[] = new Button(i);
// Xify a random button for a random time
buttons[random.nextInt(NUM_BUTTONS)].xify()I'd create a:
class Button extends JButton
* provides a constructor(int index) which sizes and places the button according to it's index
* provides an "xify" method, which setText("X"), then sets-up a SwingTimer to setText(null) after a random time.
Cheers. Keith.

Why arrays length is defined to be a field not a method in Java?

Why arrays length is defined to be a field not a method in Java?

TRANSLATE result USING R.
This statement replaces all characters in field result according to the substitution rule stored in field string R . R contains pairs of letters, where the first letter of each pair is replaced by the second letter.
in your case TRANSLATE result USING '#'.
menas '#' and ' ' space are 2 pair of characters.. and # is replaced by ' ' (space).
for better understanding..
Example:
DATA: T(10) VALUE 'AbCdEfGhIj',
STRING LIKE T,
RULE(20) VALUE 'AxbXCydYEzfZ'.
STRING = T.
TRANSLATE STRING USING RULE.
WRITE / STRING.
Output:
xXyYzZGhIj
Hope this helps..

String array length

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