Java applet program for interest rate calculation

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


*/
public class Loan extends Applet
implements ActionListener,ItemListener
{
 double p,r,n,total,i;
 String param1;
 boolean month;
 Label l1,l2,l3,l4;
 TextField t1,t2,t3,t4;
 Button b1,b2;
 CheckboxGroup cbg;
 Checkbox c1,c2;
 String str;
 public void init()
 {
  l1=new Label("Balance Amount",Label.LEFT);
  l2=new Label("Number of Months",Label.LEFT);
  l3=new Label("Interest Rate",Label.LEFT);
  l4=new Label("Total Payment",Label.LEFT);
  t1=new TextField(5);
  t2=new TextField(5);
  t3=new TextField(15);
  t4=new TextField(20);
  b1=new Button("OK");
  b2=new Button("Delete");
  cbg=new CheckboxGroup();
  c1=new Checkbox("Month Rate",cbg,true);
  c2=new Checkbox("Annual Rate",cbg,true);
  t1.addActionListener(this);
  t2.addActionListener(this);
  t3.addActionListener(this);
  t4.addActionListener(this);
  b1.addActionListener(this);
  b2.addActionListener(this);
  c1.addItemListener(this);
  c2.addItemListener(this);
  add(l1);
  add(t1);
  add(l2);
  add(t2);
  add(l3);
  add(t3);
  add(l4);
  add(t4);
  add(c1);
  add(c2);
  add(b1);
  add(b2);
 }
 public void itemStateChanged(ItemEvent ie)
 {
 }
 public void actionPerformed(ActionEvent ae)
 {
  str=ae.getActionCommand();
  if(str.equals("OK"))
  {
   p=Double.parseDouble(t1.getText());
   n=Double.parseDouble(t2.getText());
   r=Double.parseDouble(t3.getText());
   if(c2.getState())
   {
    n=n/12;
   }
   i=(p*n*r)/100;
   total=p+i;
   t4.setText(" "+total);
  }
  else if(str.equals("Delete"))
  {
   t1.setText(" ");
   t2.setText(" ");
   t3.setText(" ");
   t4.setText(" ");
  }
 }
}