Java applet program for interest rate calculation

import java.awt.*;
import java.awt.event.*;
import java.applet.*;
/*
<applet code="Loan" width=300 height=300>
</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(" ");
		}
	}
}