How to generate GUI with multiple buttons and incrementing labels on them?

I am trying to generate a GUI using swing that creates a frame with 100 buttons and every button has a "label" on it from on 1 to a 100.

What I have tried:

import javax.swing.*;
import java.awt.*;

public class ButtonScreen extends JFrame{
    JFrame frame = new JFrame();
    int rows=10;
    int cols=10;
    JButton[][] button = new JButton[rows][cols];
    JTextArea screen = new JTextArea();
    JPanel bpanel = new JPanel();
        public static void main(String[] args) {

        ButtonScreen bs = new ButtonScreen();
        bs.setVisible(true);
    }// end of main

   public ButtonScreen(){
    super("Welcome to the ButtonScreen Program!");
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    bpanel.setLayout(new GridLayout(rows,cols));


    for(int i=0;i<button.length;i++){
        for(int j=0;j<button.length;j++){
            
                button[i][j]=new JButton(""+i+j);
                bpanel.add(button[i][j]);
         }
    }
    add(bpanel);
   }//end of constructor
}//end of class

This works just fine, but it creates buttons with "labels" (meaning string parameters at line 26) and also these labels, are not one string or one integer but it is a dillusion of the of i right next to j counter. So my second attempt, after some corrections, was:

import java.awt.*;
import javax.swing.*;


public class LabArr extends JFrame{
    JFrame frame = new JFrame();
    int rows=10;
    int cols= 10;
    int i=0;
    JButton[][] button = new JButton[rows][cols];
    JLabel[] label = new JLabel[100];

    public static void main(String[] args) {
        LabArr la = new LabArr();
        la.setVisible(true);
    }//end of main 

    public LabArr(){
        super("title");
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setLayout(new GridLayout(rows,cols));

        for(i=0;i<label.length;i++){
            label[i]= new JLabel(toString(i));
        }

        for(int i=0;i<button.length;i++){
            for(int j=0;j<button.length;j++){
                button[i][j]= new JButton(""+label[j]);
              
               add(button[i][j]);
            }
        }


    }//end of constructor

    public String toString(int k){
        k=i;
        String s;
        s=""+k;
        return s;
    }
    
}//end of class 

My goal using that was to create an array of JLabel objects and then match every JLabel element to one from the JButton array.

So, first of all I would like to know to which object the methods setLayout and setDefaultCloseOperation refer to.

Second, "Does the toString method need to refer to an object at the line I am using it?". And finally, what am I missing?

This will create a single frame with buttons from 1 to 100.

import javax.swing.*;
import java.awt.GridLayout;

public class HundredButtonGrid{

    public static void main(String[] args){
        JFrame frame = new JFrame("100 buttons");
        frame.setLayout(new GridLayout(10, 10));
        for(int i = 0; i<100; i++){
            frame.add( new JButton( "" + (i + 1) ) );
        }
        frame.pack();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);

    }

}

I've addressed a few things.

• I just use 1 index because the GridLayout takes care of the x/y values.
• I used parenthesis to add the index to 1 so that it doesn't end up concatenating them by string.
• I've set the default close operation to exit, you can have it do other things too. Like JFrame.DISPOSE_ON_CLOSE so the window will go away, but not terminate the application.
• I didn't extend JFrame, I created a separate instance. In your case you have extended JFrame, so when you call setLayout it is being called on the instance you're creating. An alternative way to say it is this.setLayout same with setDefaultCloseOperation.

Hope this will help you with your problem, kindly see the code below:

public class LabArr extends JFrame{
    JFrame frame = new JFrame();
    int rows=10;
    int cols= 10;
    int counter = 0;

    JButton[][] button = new JButton[rows][cols];
    JLabel[] label = new JLabel[rows*cols];

    public static void main(String[] args) {
        DemoApplication la = new DemoApplication();
        la.setVisible(true);
    }//end of main

    public LabArr(){
        super("title");
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setLayout(new GridLayout(rows,cols));

        for(int i=0;i<label.length;i++){
            label[i]= new JLabel(toString(i));
        }

        for(int i=0;i<button.length;i++){
            for(int j=0;j<button.length;j++){
                button[i][j]= new JButton(counter + "");

                add(button[i][j]);
                counter++;
            }
        }


    }//end of constructor

    public String toString(int k){

        String s;
        s=""+k;
        return s;
    }

}

You've been creating the buttons with the label toString() method name.