Thread: problem in 2D array of TextField

I have a problem in this code.I can't display the array of Text Field.

import javax.swing.*;
import java.awt.*;
 
public class Projct extends JFrame {
    int x=3;
 
public Projct(){
 
    Container c=getContentPane();
    c.setLayout(new BorderLayout());
 
    JPanel p=new JPanel();
    //new GridLayout(x,x)
    c.add(p,BorderLayout.CENTER);
JTextField [][] array=new JTextField[x][x];
    for(int i=0;i<x;i++){
         for(int j=0;j<x;j++){
 
           array[i][j].setText(" ");
 
             p.add(array[i][j]);
 
 
 
}
    }
 
int m=x;
 double [][] data=new double [m][m];
 
     for(int i=0;i<m;i++){
         for(int j=0;j<m;j++){
             if (i == j) {
             data[i][j]=1;
          array[i][j].setText("1");
         array[i][j].setEnabled(false);
 
             }
    else{
 
 
            data[i][j]=Double.parseDouble(array[i][j].getText());
              data[j][i]=(1/data[i][j]);
             }}}
 
 
 
    }
 
public static void main(String[]arg){
    Projct f=new Projct();
    f.setTitle("AHP");
    f.setVisible(true);
    f.setSize(500, 500);
    f.setLocation(40,60);
   f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 
}
 
}

Define can't display...does it compile? Are there any exceptions? (hint: see Common Java Mistakes)

Originally Posted by copeg

Define can't display...does it compile? Are there any exceptions? (hint: see Common Java Mistakes)

no it doesn't compile

Exception in thread "main" java.lang.NullPointerException
at Projct.<init>(Projct.java:20)
at Projct.main(Projct.java:52)
Java Result: 1
BUILD SUCCESSFUL (total time: 1 second)




i don't know the order of writing the arrays
1st array is array of Text Field
2nd array is array of values that will enter by user

I want the result to be like this pic

Originally Posted by copeg

Based upon that it sure looks like it compiles...a NullPointerException is a runtime exception . Did you have a look at the link I posted above? You've created an array without initializing its elements.

thanks for this information.

I read
Problem description: Forgetting to initialize a variable
Problem description: Array Indices/Off by 1 errors

but my problem is how can I initialize the variable of 2D array
I want blank text fields then the user only type the values of upper triangle then the program will assign this values to the inverted triangle , diagonal will be always = 1 by setTextField

I have an exam & I want to find the solve

Thank you very much
array[ ][ ] is work and the frame is appear , now I have to complete my code then data [ ] [ ] will work