Calculator Demo

     import java.applet.*;

     import java.awt.*;

     import java.awt.event.*;

      public class Cal extends Applet implements ItemListener,ActionListener

     {

              Button b1;

              Label l1,l2,l3;

             TextField t1,t2,t3;

             Checkbox c1,c2,c3,c4;

             CheckboxGroup cbg; String msg="";

             long a,b;

           public void init()

          {

                l1=new Label("First Number:");

                l2=new Label("Second Number:");

                l3=new Label("The Result Is:");

                t1=new TextField(6);

                t2=new TextField(6);

                t3=new TextField(12);

               b1=new Button("Calculate");

              cbg=new CheckboxGroup();

              c1=new Checkbox("Add",cbg,true);

              c2=new Checkbox("Sub",cbg,false);

              c3=new Checkbox("Mul",cbg,false);

              c4=new Checkbox("Div",cbg,false);

             setLayout(new GridLayout(6,6));

               add(l1); add(t1); add(l2); add(t2);

               add(l3); add(t3);

               add(c1); add(c2); add(c3); add(c4);

              add(b1);

            b1.addActionListener(this);

            c1.addItemListener(this);

            c2.addItemListener(this);

      

 c3.addItemListener(this);

             c4.addItemListener(this);

       }

     public void actionPerformed(ActionEvent e)

      {

            msg=e.getActionCommand();

            a=Integer.parseInt(t1.getText());

            b=Integer.parseInt(t2.getText());

        if(msg.equals("Calculate"))

        {

            if("Add".equals(cbg.getSelectedCheckbox().getLabel()))

                      t3.setText(String.valueOf(a+b));

          else if("Sub".equals(cbg.getSelectedCheckbox().getLabel()))

                     t3.setText(String.valueOf(a-b));

          else if("Mul".equals(cbg.getSelectedCheckbox().getLabel()))

                      t3.setText(String.valueOf(a*b));

          else if("Div".equals(cbg.getSelectedCheckbox().getLabel()))

                     t3.setText(String.valueOf(a/b));

        }   

       repaint();  

     }

     public void itemStateChanged(ItemEvent e)

     {

       repaint();

     }

 }

 /*<applet code="Cal.java" width=300 height=250>

    </applet> */