FlowLayout layout = new FlowLayout(); 
setLayout(layout);
add(new Button("Start"));
add(new Button("Stop"));
add(new Button("Cut"));
add(new Button("Paste"));
add(new Button("Copy"));
add(new Button("Clear"));
  

setLayout(new BorderLayout());
add("North", new Label("Title area"));
add("South", new Label("Footnote area"));
add("East", new Button("Right"));
add("West", new Button("Left"));
add("Center", new TextArea("hello, textarea"));
  

// 3 rows and 3 columns  with gaps of size 5
setLayout( new GridLayout(3,3,5,5) );
add(new Button("1"));
add(new Button("2"));
add(new Button("3"));
add(new Button("4"));
add(new Button("5"));
add(new Button("6"));
add(new Button("7"));
add(new Button("8"));
  

• What if we want to draw something else?

• This package defines all the event classes and interfaces for event handling.
• You need the following to import all the event classes as follows:
            import java.awt.event.*
  
• The importing mechanism does not import classes in a subdirectory recursively.
  So even though you already did the following
            import java.awt.*
  you still need to do
            import java.awt.event.*
  
• All the event classes inherit from the class java.awt.AWTEvent in package Java.awt (see here).

import java.awt.*;
import java.applet.*;
import java.awt.event.*;

public class ButtonEventDemo extends Applet {

   Button button1, button2;
   TextField textfield;

   class MyButtonEventListener implements ActionListener {

       public void actionPerformed(ActionEvent e) {

           if (e.getSource().equals(button1)) {
               textfield.setText("   somebody pressed the button");
           } 
           else if (e.getSource().equals(button2)) {
               
               textfield.setText("");
           }
       }
   }

   public void init () {

       button1 = new Button("Press me");
       button2 = new Button("Clear");
       textfield = new TextField(30);       
    
       MyButtonEventListener listener 
            = new MyButtonEventListener();

       button1.addActionListener(listener);
       button2.addActionListener(listener);

       add(button1);
       add(button2);
       add(textfield);
   }
}

• Class MyButtonEventListener is defined as an inner class which you have not learned yet.
• Just consider an inner class as an usual class for right now.
• There are many bad things of inner classes.
• One of the good things is that from inside the inner class we can directly access the data members of the class inside whih the inner class is defined.
• Class MyButtonEventListener only implements interface ActionListener in this example. However, you can implement as many interfaces as you want, depending on what types of events you want to handle.
• This example could also be equivalently written in some other ways (without defining a separate class for listening to the events), as follows.

import java.awt.*;
import java.applet.*;
import java.awt.event.*;

public class ButtonEventDemo extends Applet implements ActionListener {

   Button button1, button2;
   TextField textfield;


   public void actionPerformed(ActionEvent e) {

           if (e.getSource().equals(button1)) {
               textfield.setText("   somebody pressed the button");
           } 
           else if (e.getSource().equals(button2)) {
               
               textfield.setText("");
           }
   }

   public void init () {

       button1 = new Button("Press me");
       button2 = new Button("Clear");
       textfield = new TextField(30);       
    
       button1.addActionListener(this);
       button2.addActionListener(this);

       add(button1);
       add(button2);
       add(textfield);
   }
}

import java.awt.*;
import java.applet.*;
import java.awt.event.*;

public class ButtonEventDemo3 extends Applet {

   Button button1, button2;
   TextField textfield;

   public void init () {

       button1 = new Button("Press me");
       button2 = new Button("Clear");
       textfield = new TextField(30);       
    
       button1.addActionListener(
           new ActionListener() 
           {
                public void actionPerformed(ActionEvent e) {

                   textfield.setText("   somebody pressed the button");

                }
           }
       );

       button2.addActionListener(
           new ActionListener() 
           {
                public void actionPerformed(ActionEvent e) {

                   textfield.setText("");

                }
           }

       );

       add(button1);
       add(button2);
       add(textfield);
   }
}