Calculator in java Applet

This is a very small introductory calculator, made with java applet. This only demonstrates introductory functionality.

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

public class MyApplet extends Applet implements ActionListener {
	String msg = " ";
	int v1, v2, result;
	TextField t1;
	Button b[] = new Button[10];
	Button add, sub, mul, div, clear, mod, EQ;
	char OP;

	public void init() {
		Color k = new Color(120, 89, 90);
		setBackground(k);
		t1 = new TextField(20);

		FlowLayout gl = new FlowLayout();
		for (int i = 0; i < 10; i++) {
			b[i] = new Button("" + i);
		}
		add = new Button("add");
		sub = new Button("sub");
		mul = new Button("mul");
		div = new Button("div");
		mod = new Button("mod");
		clear = new Button("clear");
		EQ = new Button("EQ");
		t1.addActionListener(this);
		add(t1);
		for (int i = 0; i < 10; i++) {
			add(b[i]);
		}
		setLayout(gl);
		add(add);
		add(sub);
		add(mul);
		add(div);
		add(mod);
		add(clear);
		add(EQ);
		for (int i = 0; i < 10; i++) {
			b[i].addActionListener(this);
		}
		add.addActionListener(this);
		sub.addActionListener(this);
		mul.addActionListener(this);
		div.addActionListener(this);
		mod.addActionListener(this);
		clear.addActionListener(this);
		EQ.addActionListener(this);
	}

	public void actionPerformed(ActionEvent ae) {
		String str = ae.getActionCommand();
		char ch = str.charAt(0);
		if (Character.isDigit(ch))
			t1.setText(t1.getText() + str);
		else if (str.equals("add")) {
			v1 = Integer.parseInt(t1.getText());
			OP = '+';
			t1.setText("");
		} else if (str.equals("sub")) {
			v1 = Integer.parseInt(t1.getText());
			OP = '-';
			t1.setText("");
		} else if (str.equals("mul")) {
			v1 = Integer.parseInt(t1.getText());
			OP = '*';
			t1.setText("");
		} else if (str.equals("div")) {
			v1 = Integer.parseInt(t1.getText());
			OP = '/';
			t1.setText("");
		} else if (str.equals("mod")) {
			v1 = Integer.parseInt(t1.getText());
			OP = '%';
			t1.setText("");
		}
		if (str.equals("EQ")) {
			v2 = Integer.parseInt(t1.getText());
			if (OP == '+')
				result = v1 + v2;
			else if (OP == '-')
				result = v1 - v2;
			else if (OP == '*')
				result = v1 * v2;
			else if (OP == '/')
				result = v1 / v2;
			else if (OP == '%')
				result = v1 % v2;
			t1.setText("" + result);
		}
		if (str.equals("clear")) {
			t1.setText("");
		}
	}
}