Program to design an applet for simple calculator for 4 arithmetic operations.

/*<applet code=Calc25.class width=500 height=500>      </applet> */
import java.applet.*;
import java.awt.*;
import java.awt.event.*;

public class Calc25 extends Applet implements ActionListener
{
    String cmd[]={"7","8","9","/","4","5","6","*","1","2","3","-","0","C","=","+"};
    int pv=0;
    String op=" ";
    Button b[]=new Button[16];
    TextField t1=new TextField(10);

    public void init()
    {
        setLayout(new BorderLayout());
        add(t1,"North");
        t1.setText("0");

        Panel p=new Panel();
        p.setLayout(new GridLayout(4,4));

        for(int i=0;i<16;i++)
        {
            b[i]=new Button(cmd[i]);
            b[i].setFont(new Font("Arial",Font.BOLD,25));
            p.add(b[i]);
            add(p,"Center");
            b[i].addActionListener(this);
        }
    }

    public void actionPerformed(ActionEvent ae)
    {
        int res=0;
        String cap=ae.getActionCommand();
        int cv=Integer.parseInt(t1.getText());

        if(cap.equals("C"))
        {
            t1.setText("0");
            pv=0;
            cv=0;
            res=0;
            op="";
        }
        else if(cap.equals("="))
        {
            res=0;
            if(op=="+")
                res=pv+cv;
            else if(op=="-")
                res=pv-cv;
            else if(op=="*")
                res=pv*cv;
            else if(op=="/")
                res=pv/cv;
           
            t1.setText(String.valueOf(res));

        }
        else if(cap.equals("+") || cap.equals("-") || cap.equals("*") || cap.equals("/"))
        {
            pv=cv;
            op=cap;
            t1.setText("0");
        }

        else
        {
            int v=cv*10+Integer.parseInt(cap);
            t1.setText(String.valueOf(v));
        }
    }
}