Handling Button in java

In this example we are going to control Button.
To control the button we are using three type of package. One is java.awt.* second is  java.applet.* and third is java.awt.event.*; .The java.awt.* is used for GUI interface. AWT classes are contain in this package. The  java.applet.* package is used to create an applet and java.awt.event.*; defined within the java.awt.*; package is a subclass of EventObject. It is a super class of all AWT-based event..

Button defines two constructors:

Button(): Is use to create an empty button.
Button (String str) : Is use to create a button that contains String str as label.
Action Listner() defines one method to receive action event.

Each time a button is pressed ,an action is generated. this is send to any listeners that previously registered an interest in receiving action from that component.
In our example first we implement ActionListener() each listener implement the ActionLinstner.
When the button is pressed or an event is occur ActionPerformed() interface is called.
In our example we creates  four button Jan, Nov, Dec, Feb. Each time one is pressed a message is displayed that report which button has been pressed. The label of the button is used to determine which button has been pressed.
The label is obtained by calling the get.ActionCommand() method on the ActionEvent object passed to actionPerformed().

//creat Button
import java.awt.*;
import java.applet.*;
import java.awt.event.*;
/*
<applet code="ButtonDemo" width=300 height=200>
</applet>
*/
public class ButtonDemo extends Applet implements ActionListener{
String msg="which is the last month ?";
Button one,two,three,four;
public void init()
{
 one = new Button("Jan");
 two = new Button("Nov");
 three = new Button("Dec");
 four = new Button("Feb");
add(one);
add(two);
add(three);
add(four);
one.addActionListener(this);
two.addActionListener(this);
three.addActionListener(this);
four.addActionListener(this);
}
public void actionPerformed(ActionEvent ae){
String str=ae.getActionCommand();
if(str.equals("Jan")){
msg="Your answer is Jan";
}
else if(str.equals("Nov")){
msg="Your answer is Nov";
}
else if(str.equals("Dec")){
msg="Your answer is Dec";
}
else if(str.equals("Feb")){
msg="Your answer is Feb";
}
repaint();
}
public void paint(Graphics g){
g.drawString(msg,6,100);
}}

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Output Of Example