can i change toggle button's state to another (play state to pause),by clicking another button(stop)

yes. Just call the appropriate method for the toggle button in your action performed method for the stop button

You can. As JamesCherrill said, you'll need to add a functionality to each of your GUI components, so that it would handle the "events" generated by the user.

Here's a small example. We have a button named "Click me", which can be pressed. Near him there's a label named "Clicks: " and a number. That number indicates the number of times the user clicked that button.

import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

public class Sb extends JFrame{
    private static final long serialVersionUID = 1L;
    private JButton nrClicks = new JButton("Click me!");
    private JLabel clicks_lbl = new JLabel("Clicks: 0");
    private int clicks = 0;

    public Sb(){
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        nrClicks.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                clicks_lbl.setText("Clicks: "+Integer.toString(++clicks));
            }
        });
        JPanel main = new JPanel(new GridLayout(1, 2));
        main.add(nrClicks);
        main.add(clicks_lbl);
        add(main);
    }

    public static void main(String args[]){
        Sb sb = new Sb();
        sb.pack();
        sb.setVisible(true);
    }
}

As you can see, I've added an annonymouss inner class of type ActionListener which adds a handle functionality for that button, when an event occurs (which in our case is consisted by the user clicking the button).
You can also have a separate class in which you define your event handling things, but it should always implement a listener class (which "listens" for events). There are a lot of listener classes, you should check the API for more info about them.
For buttons, here's an useful link: Click Here

can i change toggle button's state to another (play state to pause),by clicking another button(stop)

  • JToggleButton.setSelected(true / false) (inherits from JCheckBox / JRadioButton, has two states)

  • use ItemListener (returns SELECTED / DESELECTED, then easy to test), otherwise you have to test for isSelected()