I want to create a quiz using swing and awt but i am getting lot of exceptions ,

Question

I want to add item listener inside of an action listener, so that whenever the user presses the checkbox and clicks the buttons the frame displays a label whether the answer is true or not. Here is the code:

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

public class KBC implements ItemListener {

    JFrame f;
    JLabel l;
    JButton b;
    JCheckBox k0;
    JCheckBox k1;
    JCheckBox k2;
    JCheckBox k3;
    JCheckBox k4;
    JLabel z;

    public static void main(String[] args) {
        KBC u = new KBC();
        u.go();
    }

    public void go() {
        z = new JLabel("Nothing");
        f = new JFrame("Hello");
        l = new JLabel("q1- Ans is 3");
        b = new JButton("Click");
        k0 = new JCheckBox("hello1");
        k1 = new JCheckBox("hello2");
        k2 = new JCheckBox("hello3");
        k3 = new JCheckBox("hello4");
        k4 = new JCheckBox("hello5");
        l.setFont(new Font("serif", Font.BOLD, 50));
        b.addActionListener(new ButtonAction());
        f.setLayout(null);
        f.setSize(1024, 768);
        f.setVisible(true);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        l.setBounds(150, 100, 500, 100);
        k0.setBounds(200, 300, 50, 100);
        k1.setBounds(200, 320, 100, 100);
        k2.setBounds(200, 340, 100, 100);
        k3.setBounds(200, 360, 100, 100);
        k4.setBounds(200, 380, 100, 100);
        b.setBounds(600, 550, 100, 100);
        f.add(l);
        f.add(k0);
        f.add(k1);
        f.add(k2);
        f.add(k3);
        f.add(k4);
        f.add(b);
        f.add(z);

        k0.setVisible(true);
        k1.setVisible(true);
        k3.setVisible(true);
        k4.setVisible(true);
        b.setVisible(true);
        z.setVisible(true);
        k2.setVisible(true);
        l.setVisible(true);
    }

    @Override
    public void itemStateChanged(ItemEvent eve) {
        if (eve.getSource() == k3) {
            z.setText("YOu are r8");
        } else {
            z.setText("YOu are rong");
        }
    }
}

class ButtonAction extends KBC implements ActionListener {

    @Override
    public void actionPerformed(ActionEvent e) {
        k0.addItemListener(new KBC());
        k1.addItemListener(new KBC());
        k2.addItemListener(new KBC());
        k3.addItemListener(new KBC());
        k4.addItemListener(new KBC());
    }
}

Avoid using `null` layouts, pixel perfect layouts are an illusion within modern ui design. There are too many factors which affect the individual size of components, none of which you can control. Swing was designed to work with layout managers at the core, discarding these will lead to no end of issues and problems that you will spend more and more time trying to rectify. [Why is it frowned upon to use a null layout in SWING?](http://stackoverflow.com/questions/6592468/why-is-it-frowned-upon-to-use-a-null-layout-in-swing) — MadProgrammer, Feb 04 '17 at 05:54
*"i want to add item listener inside of an Action listener"* - Why? Why does it need to be add in the `ActionListener`, why not register them when you make the UI — MadProgrammer, Feb 04 '17 at 05:58
`ButtonAction` is not an instance class of `KBC`, so your reference to `k0` is `null` when the `actionPerformed` method is triggered. Perhaps you should have a look at [Inner Classes](https://docs.oracle.com/javase/tutorial/java/javaOO/innerclasses.html) — MadProgrammer, Feb 04 '17 at 05:59

I want to create a quiz using swing and awt but i am getting lot of exceptions ,

0 Answers0