import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
 
public class calculator extends JApplet
{
	static JLabel resultLabel;
	static JLabel entryLabel;
	static JLabel outputLabel;
	static JTextField enterNum;
	static JButton adding;
	static JButton subtracting;
	static JButton clearbutton;
	static double result;
 
          //listener for clear button
	static class clearHandler implements ActionListener
	{
		public void actionPerformed(ActionEvent event)
		{
			result=0.0;
			outputLabel.setText("0.0");
			enterNum.setText("");
 
		}
	}
           //listener for adding and subtracting buttons
	static class operatorHandler implements ActionListener
	{
		public void actionPerformed(ActionEvent event)
		{
			double secondoperand=0.0;
		        secondoperand=Double.parseDouble(enterNum.getText());
			String whichbutton=event.getActionCommand();
			if (whichbutton.equals("+"))
			result=result+secondoperand;
			else if (whichbutton.equals("-"))
			result =result-secondoperand;
			outputLabel.setText(result+" ");
			enterNum.setText("");
 
		}
	}
 
 
	operatorHandler operation;
	clearHandler clearing;
 
	public void init()
{
	result=0.0;
	resultLabel=new JLabel("result: ");
	entryLabel=new JLabel("enter #: ");
	outputLabel=new JLabel("0.0");
	adding=new JButton("+");
	subtracting=new JButton("-");
	clearbutton =new JButton("clear");
	enterNum=new JTextField("value here ",10);
 
	adding.addActionListener(operation);
	subtracting.addActionListener(operation);
	clearbutton.addActionListener(clearing);
 
	add(resultLabel);
	add(outputLabel);
	add(entryLabel);
	add(enterNum);
	add(adding);
	add(subtracting);
	add(clearbutton);
	setLayout(new GridLayout(4,1));
 
}
}