Rerun an app

[Adam Burda]

Hi all,
Im making an app that does time tables for my kid.
I can not find away to rerun the app if the answer is right, after clicking the JButton.
Here is my code. And thank you for your help.

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

public class TimesP extends JPanel
{
  public JLabel lb1, lb2, lb3, lb4, lb5;
  public JTextField tf1;
  public int a, b, c, d;

  public TimesP()
  {
    this.setBackground(Color.GREEN);
    
    int[] numListOne = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12};
    int[] numListTwo = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12};

    int oneLength = numListOne.length;
    int twoLength = numListTwo.length;

    int rand1 = (int) (Math.random() * oneLength);
    int rand2 = (int) (Math.random() * oneLength);

    a = numListOne[rand1];
    b = numListTwo[rand2];
    c = a*b;
    
    String op1 = Integer.toString(a);
    String op2 = Integer.toString(b);

    lb1 = new JLabel(op1);
    lb2 = new JLabel(" X ");
    lb3 = new JLabel(op2);
    lb4 = new JLabel(" = ");
    tf1 = new JTextField(2);
    JButton b1 = new JButton("Answer!");
    ButtonListener listener = new ButtonListener();
    b1.addActionListener(listener);
    

    lb5 = new JLabel(" ");

    add(lb1);
    add(lb2);
    add(lb3);
    add(lb4);
    add(tf1);
    add(b1);
    add(lb5);
  }

  private class ButtonListener implements ActionListener
  {
    public void actionPerformed (ActionEvent event)
    {
      String ans = tf1.getText();
      d = Integer.parseInt(ans);

      if(d == c)
        {
        lb5.setText("Good Job!");
        tf1.setText(null);      
        }
        else
        {
        lb5.setText("Try again...");
        tf1.setText(null);
        }
    }
  } 
}

[Kemal Sokolovic]

You would have to put the code for generating new multiplication questions in a separate method.

The code you have does pretty much everything in constructor. What you should do in a constructor is just initialize GUI components and put them on your panel. Labels for operands would be initialized with empty strings, since operands will be chosen in a separate method you are about to define.

Then you define another method (say generateNewMultiplicationQuestion()) that would contain the logic for picking random numbers from those arrays (the code you already have) and once you pick the numbers you would just setText() method to set them to labels:

private void generateNewMultiplicationQuestion()
{
    // the same code for picking up the values from arrays

    lb1.setText(op1);
    lb3.setText(op2);
}

This method can then be invoked each time you want to generate a new question after the answer to the current one is correct:

if (d == c)
{
    lb5.setText("Good Job!");
    tf1.setText("");
    // The answer is correct, now generate new one
    generateNewQuestion();
}

If you want the question to be initialized as soon as you run the application, than you would invoke the above method once at the end of your constructor.

Also note what happens when you click the button without providing an answer (or providing text as an answer).

[Adam Burda]

Thank you. It works now.