import awb.*;
import java.awt.*;
import java.awt.event.*;

public class ErrorDemo extends java.applet.Applet 
		implements ActionListener
{
	double data, extra;
	DoubleField dataF, extraF;
	Button b1;
	public void init ()
	{
		dataF = new DoubleField(20);
		dataF.setLabel("Data");
		extraF = new DoubleField(20);
		extraF.setLabel("Extra");
		b1 = new Button("Compute");
		b1.addActionListener(this);
		add(dataF);
		add(extraF);
		add(b1);
		dataF.setDouble(0);
		extraF.setDouble(0);
	}

	public void actionPerformed(ActionEvent event)
	{	
		Object cause = event.getSource();
		if (cause == b1)
		{
		      data = dataF.getDouble();
		      extra = extraF.getDouble();
		      data = data + extra;
		      data = data - extra;
		      dataF.setDouble(data);
		}
	}
}