// <applet code="Kalkylator" width="300" height="200"></applet>

import javax.swing.*;
import java.awt.event.*;
import java.awt.*;

public class Kalkylator extends JApplet implements ActionListener {
    private JLabel label1 = new JLabel("Ena talet:");
    private JTextField text1 = new JTextField(10);
    private JLabel label2 = new JLabel("Andra talet: ");
    private JTextField text2 = new JTextField(10);
    private JLabel label3 = new JLabel("Resultat: ");
    private JTextField text3 = new JTextField(10);
    private JButton plusknappen = new JButton("+");
    private JButton minusknappen = new JButton("-");
    private JButton gångerknappen = new JButton("*");
    private JButton delatknappen = new JButton("/");
    private JButton rotknappen = new JButton("Roten");
    private JButton kvadratknappen = new JButton("Kvadraten");

    public void init() {
        plusknappen.addActionListener(this);
	minusknappen.addActionListener(this);
	gångerknappen.addActionListener(this);
	delatknappen.addActionListener(this);
	rotknappen.addActionListener(this);
	kvadratknappen.addActionListener(this);
        Container cp = getContentPane();
        cp.setLayout(new FlowLayout());
        cp.add(label1);
        cp.add(text1);
        cp.add(label2);
        cp.add(text2);
        cp.add(label3);
        cp.add(text3);
        cp.add(plusknappen);
        cp.add(minusknappen);
        cp.add(gångerknappen);
        cp.add(delatknappen);
        cp.add(rotknappen);
	cp.add(kvadratknappen);
    }

    public void actionPerformed(ActionEvent e) {
	JButton knappen = (JButton)e.getSource();
	String str1 = text1.getText();
	String str2 = text2.getText();
	    
	try {
	    float tal1 = Float.parseFloat(str1);
	    float tal2 = Float.parseFloat(str2);
	    String resultatsträngen;

	    if (Float.isNaN(tal1))
		resultatsträngen = "Error!";
	    else if (Float.isNaN(tal2))
		resultatsträngen = "Error!";
	    else if (knappen == plusknappen) {
		resultatsträngen = "" + (tal1 + tal2);
	    }
	    else if (knappen == minusknappen) {
		resultatsträngen = "" + (tal1 - tal2);
	    }
	    else if (knappen == gångerknappen) {
		resultatsträngen = "" + (tal1 * tal2);
	    }
	    else if (knappen == delatknappen) {
		if (tal2 == 0)
		    resultatsträngen = "Error!";
		else
		    resultatsträngen = "" + (tal1 / tal2);
	    }
	    else if (knappen == rotknappen) {
		if (tal1 < 0)
		    resultatsträngen = "Error!";
		else
		    resultatsträngen = "" + Math.sqrt(tal1);
	    }
	    else if (knappen == kvadratknappen) {
		resultatsträngen = "" + (tal1 * tal1);
	    }
	    else {
		resultatsträngen = "Error!";
	    }
	    text3.setText(resultatsträngen);
	}
	catch (NumberFormatException exc) {
	    text3.setText("Error!");
	}
    } // actionPerformed
} // class Kalkylator