import java.applet.Applet;
import java.awt.*;

public class Calculator extends Applet
{
	Button add;
	Button equals;
	Button clear;
	TextField result;
	float current = 0;
	public void init()
	{
		add = new Button("+");
		add(add);
		equals = new Button("=");
		add(equals);
		clear = new Button("Clear");
		add(clear);
		result = new TextField(20);
		add(result);
	}
	public boolean action(Event event, Object arg)
	{
		if (event.target == add) {
			addToCurrent();
			result.setText("");
			result.requestFocus();
		} else if (event.target == equals) {
			addToCurrent();
			String s = Float.toString(current);
			result.setText(s);
			result.requestFocus();
		} else if (event.target == clear) {
			current = 0;
			result.setText("");
			result.requestFocus();
		}
		return true;
	}
	void addToCurrent() {
		String text = result.getText();
		Float value = Float.valueOf(text);
		current += value.floatValue();
	}
}