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JButton class is used to create a push button control, which can generate an ActionEvent when it is clicked. In order to handle a button click event, the ActionListener interface should be implemented. JButton is a component which extends the JComponent class and it can be added to a container.

Constructors of JButton

An example of JButton

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



public class Btn1
{
public static void main(String... ar)
{
SwingUtilities.invokeLater(new Runnable() {
public void run()
{
new A();
}
});

}//Closing the main method

}//Closing the class A


class A 
{
JFrame jf;
JButton button1, button2, button3;


A()
{
jf= new JFrame();
button1= new JButton();
button2= new JButton("Click here");
button3= new JButton();

button3.setText("Button3");



jf.add(button1);
jf.add(button2);
jf.add(button3);

jf.setLayout(new FlowLayout());
jf.setSize(300,100);
jf.setVisible(true);
}

}

When you run the code, you are presented a window shown below -:

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Setting an image over JButton

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



public class Btn4
{
public static void main(String... ar)
{
SwingUtilities.invokeLater(new Runnable() {
public void run()
{
new A();
}
});

}//Closing the main method
}//Closing the class A


class A 
{
JFrame jf;

JButton button1, button2, button3, button4;

A()
{
jf= new JFrame();

//Setting an image over a JButton and limited its border space, so that image fits perfectly over JButton.
button1= new JButton(new ImageIcon("JButton1.jpg"));
button1.setBorder(new EmptyBorder(2,2,2,2));

//Setting an image over a JButton with and without text.
button2 = new JButton(new ImageIcon("Smiley3.jpg"));
button3 = new JButton("Smiley", new ImageIcon("Smiley3.jpg"));

//Setting a big image over a JButton
button4 = new JButton(new ImageIcon("Big Smiley", "BigSmiley.gif"));
button4.setHorizontalTextPosition(SwingConstants.LEFT);	

jf.add(button1);
jf.add(button2);
jf.add(button3);
jf.add(button4);


jf.setLayout(new FlowLayout());
jf.setSize(300,300);
jf.setVisible(true);
}

}

When you run the code, you are presented a window shown in the Figure2 below -:

Handling button click events by implementing ActionListener interface

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


public class Btn5
{
public static void main(String... ar)
{
SwingUtilities.invokeLater(new Runnable() {
public void run()
{
new A();
}
});

}//Closing the main method
}//Closing the class A


class A implements ActionListener
{
JFrame jf;
JButton button1, button2;
JLabel label;


A()
{
jf= new JFrame();
button1= new JButton("Yes");
button2= new JButton("No");
label = new JLabel();


jf.add(button1);
jf.add(button2);
jf.add(label);


button1.addActionListener(this);
button2.addActionListener(this);


jf.setLayout(new FlowLayout(FlowLayout.CENTER,60,10));
jf.setSize(250,150);
jf.setVisible(true);
}


public void actionPerformed(ActionEvent ae)
{
if(ae.getActionCommand().equals("Yes"))
{
label.setText("You've clicked Yes");
jf.add(label);
jf.setVisible(true);
System.out.println("Yes button is clicked");
}

if(ae.getActionCommand().equals("No"))
{
label.setText("You've clicked No");
jf.add(label);
jf.setVisible(true);
System.out.println("No button is clicked");
}
}

}

When you run the code, you are presented a window shown in the Figure3 below -:



When you click on any of the buttons, you will be displayed an appropriate message, for example, when we click on Yes button, we get such message -

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