// filename: Average.java
import java.awt.*;
import java.applet.*;
import java.awt.event.*;

public class Average extends Applet implements ActionListener
{
    public TextField input1, input2, display;
    public Label labelTitle, label1input, label2input, label3display;
    public Button b1;
    public int num1, num2;
    public double avg;
         
    public void init( )
    {
        input1 = new TextField(12);
        input2 = new TextField(12);
        display = new TextField(12);
    
        input1.setText("0");
        input2.setText("0");
        display.setText("");
        display.setEditable(false);
        
        labelTitle = new Label("Average Calculator");
        label1input = new Label("First Number");
        label2input = new Label("Second Number");
        label3display = new Label("Computed Average");
        
        b1 = new Button("Push to Compute Average");
        b1.addActionListener(this);
        
        add(labelTitle); add(label1input);
        add(input1); add(label2input);
        add(input2); add(b1);
        add(label3display); add(display);
    }
         
    public void actionPerformed(ActionEvent e)
    {
        num1 = Integer.parseInt(input1.getText());
        num2 = Integer.parseInt(input2.getText());
        avg = ((double)num1 + num2) / 2 ;
        display.setText(""+avg);
    }
}

    // filename: CustomAverage.java
    import java.awt.*;
    import java.applet.*;
    import java.awt.event.*;
    public class CustomAverage
    {   
         /* average is an instance variable  -- it is called
            an "instance" variable since each instance or object
            of this class will have ts own copy of this variable */
        
      public double average;
        
        // The constructor is given below – it is just initializing
        // the variable average to zero 
        public CustomAverage( )
        {
            average = 0.0;
        }

        // The following getAverage method is the only 
        // other method in the class
        // it must have two integer values provided by
        // the client class so it can sum them and compute
        // the average. The (double) in front of the
        // variable num1 is called a cast – it forces Java
        // to treat num1 as a double so the result of the
        // entire expression will be a double.
        // the type of the method is double not void – this
        // means that the method must return a double
        // to the client class.
        public double getAverage(int num1, int num2)
        {
                average = ( (double)num1 + num2) / 2;
                return average;
        }
    }

// filename: AverageApplet.java
import java.awt.*;
import java.applet.*;
import java.awt.event.*;

public class AverageApplet extends Applet implements ActionListener
{
    public CustomAverage average; // instantiate a CustomAverage object "average"
    public TextField input1, input2, display;
    public Label labelTitle, label1input, label2input, label3display;
    public Button b1;
    public int num1, num2;
    public void init( )
    {
        average =new CustomAverage( ); // new the average object
        input1 = new TextField(12);
        input2 = new TextField(12);
        display = new TextField(12);
 
        input1.setText("0"); input2.setText("0");
        display.setText(""); display.setEditable(false);
                
        labelTitle = new Label("Average Calculator");
        label1input = new Label("First Number");
        label2input = new Label("Second Number");
        label3display = new Label("Computed Average");
        
        b1 = new Button("Push to Compute Average");
        b1.addActionListener(this);
        
        add(labelTitle); add(label1input);
        add(input1); add(label2input);
        add(input2); add(b1);
        add(label3display); add(display);     
    }
    
    public void actionPerformed(ActionEvent e)
    {
        // the next line uses the getAverage method 
        // in the CustomAverage class to 
        // compute the average. The two parameters of the 
        // method calls are actually 
        // method calls to the Integer class that 
        // will return the integer values the 
        // user entered into the two TextFields
        display.setText 
            (""+average.getAverage(Integer.parseInt(input1.getText()),
                                   Integer.parseInt(input2.getText()) ));
    } 
}