import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.EmptyBorder;
public class Calculator
{
public static void main(String[] args)
{
CalculatorFrame frame = new CalculatorFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setBounds(100, 100, 361, 366);
frame.setVisible(true);
}
}
class CalculatorFrame extends JFrame
{
public CalculatorFrame()
{
setTitle("Calculator");
CalculatorPanel panel = new CalculatorPanel();
add(panel);
pack();
}
}
class CalculatorPanel extends JPanel
{
public CalculatorPanel()
{
setLayout(new BorderLayout());
result = 0;
lastCommand = "=";
start = true;
display = new JButton("0");
display.setEnabled(false);
add(display, BorderLayout.NORTH);
//ActionListener insert = new InsertAction();
ActionListener command = new CommandAction();
panel = new JPanel();
panel.setBorder(new EmptyBorder(5, 5, 5, 5));
//setContentPane(panel);
panel.setLayout(null);
display.setBounds(41, 30, 269, 33);
display.setText("");
panel.add(display);
// display.setColumns(10);
JButton btn_0 = new JButton("0");
btn_0.setBounds(41, 295, 60, 23);
panel.add(btn_0);
btn_0.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent arg0)
{
display.setText(display.getText()+ "0");
}
});
JButton btn_1 = new JButton("1");
btn_1.setBounds(41, 261, 60, 23);
panel.add(btn_1);
btn_1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0){
display.setText(display.getText()+ "1");
}
});
JButton btn_2 = new JButton("2");
btn_2.setBounds(111, 261, 60, 23);
panel.add(btn_2);
btn_2.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0){
display.setText(display.getText()+ "2");
}
});
JButton btn_3 = new JButton("3");
btn_3.setBounds(181, 261, 60, 23);
panel.add(btn_3);
btn_3.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0){
display.setText(display.getText()+ "3");
}
});
JButton btn_4 = new JButton("4");
btn_4.setBounds(41, 227, 60, 23);
panel.add(btn_4);
btn_4.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0){
display.setText(display.getText()+ "4");
}
});
JButton btn_5 = new JButton("5");
btn_5.setBounds(111, 227, 60, 23);
panel.add(btn_5);
btn_5.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0){
display.setText(display.getText()+ "5");
}
});
JButton btn_6 = new JButton("6");
btn_6.setBounds(181, 227, 60, 23);
panel.add(btn_6);
btn_6.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0){
display.setText(display.getText()+ "6");
}
});
JButton btn_7 = new JButton("7");
btn_7.setBounds(41, 193, 60, 23);
panel.add(btn_7);
btn_7.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0){
display.setText(display.getText()+ "7");
}
});
JButton btn_8 = new JButton("8");
btn_8.setBounds(111, 193, 60, 23);
panel.add(btn_8);
btn_8.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0){
display.setText(display.getText()+ "8");
}
});
JButton btn_9 = new JButton("9");
btn_9.setBounds(181, 193, 60, 23);
panel.add(btn_9);
btn_9.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0){
display.setText(display.getText()+ "9");
}
});
JButton btn_pkt = new JButton(".");
btn_pkt.setBounds(111, 295, 60, 23);
panel.add(btn_pkt);
btn_pkt.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0){
display.setText(display.getText()+ ".");
}
});
JButton btn_ce = new JButton("CE");
btn_ce.setBounds(251, 147, 60, 23);
panel.add(btn_ce);
btn_ce.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0){
display.setText(display.getText().substring(0,display.getText().length()-1));
}
});
JButton btn_istgleich = new JButton("=");
btn_istgleich.setBounds(181, 295, 60, 23);
panel.add(btn_istgleich);
btn_istgleich.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0){
}
});
JButton btn_multiplikation = new JButton("*");
btn_multiplikation.setBounds(251, 193, 60, 23);
panel.add(btn_multiplikation);
btn_multiplikation.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0){
// display.setText(display.getText()+ "*");
}
});
JButton btn_division = new JButton("/");
btn_division.setBounds(251, 227, 60, 23);
panel.add(btn_division);
btn_division.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0){
display.setText(display.getText()+ "/");
}
});
JButton btn_addieren = new JButton("+");
btn_addieren.setBounds(251, 261, 60, 23);
panel.add(btn_addieren);
btn_addieren.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0){
display.setText(display.getText()+ "+");
}
});
JButton btn_subtraktion = new JButton("-");
btn_subtraktion.setBounds(251, 295, 60, 23);
panel.add(btn_subtraktion);
btn_subtraktion.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0){
display.setText(display.getText()+ "-");
}
});
/*addButton("7", insert);
addButton("8", insert);
addButton("9", insert);
addButton("/", command);
addButton("4", insert);
addButton("5", insert);
addButton("6", insert);
addButton("*", command);
addButton("1", insert);
addButton("2", insert);
addButton("3", insert);
addButton("-", command);
addButton("0", insert);
addButton(".", insert);
addButton("=", command);
addButton("+", command);
*/
add(panel, BorderLayout.CENTER);
}
private void addButton(String label, ActionListener listener)
{
JButton button = new JButton(label);
button.addActionListener(listener);
panel.add(button);
}
private class InsertAction implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
String input = event.getActionCommand();
if (start)
{
display.setText("");
start = false;
}
display.setText(display.getText() + input);
}
}
/**
* Diese Aktion führt den mit der Taste verbundenen
* Befehl aus.
*/
private class CommandAction implements ActionListener
{
public void actionPerformed(ActionEvent arg0)
{
String command = arg0.getActionCommand();
// Füge den Präfix "-" an den String an wenn
// es sich um den ersten Befehl handelt (negative Zahl)
if (start)
{
if (command.equals("-"))
{
display.setText(command);
start = false;
}
else
lastCommand = command;
}
else
{
// Berechnung ausführen
calculate(Double.parseDouble(display.getText()));
lastCommand = command;
start = true;
}
}
}
/**
* Führt die anstehenden Berechnungen aus.
* @param x der mit dem vorherigen Ergebnis zu berechnende Wert
*/
public void calculate(double x)
{
if (lastCommand.equals("+")) result += x;
else if (lastCommand.equals("-")) result -= x;
else if (lastCommand.equals("*")) result *= x;
else if (lastCommand.equals("/")) result /= x;
else if (lastCommand.equals("=")) result = x;
display.setText("" + result);
}
private JButton display;
private JPanel panel;
private double result;
private String lastCommand;
private boolean start;
}