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Simple Calculator in GUI

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2 replies [Last post]
Joined: 2014-05-06

Hi, i'm a beginner in Java, so i have try some sample code to understand more about java. it's about simple calculator in GUI form. when i compile it; it shows "selection does not contain applet". I really dont know how to fix it. Sorry for asking amateur question!!

the code is;
package calculator;

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

// A panel with calculator buttons and a result display

public class CalculatorPanel extends JPanel {

private JButton display;
private JPanel panel;
private double result;
private String lastCommand;
private boolean start;

public CalculatorPanel(){
setLayout(new BorderLayout());
result = 0;
lastCommand = "=";
start = true;

// add the display
display = new JButton("0");
add(display, BorderLayout.NORTH);

ActionListener insert = new InsertAction();
ActionListener command = new CommandAction();

//add the buttons in a 4 x 4 grid
panel = new JPanel();
panel.setLayout(new GridLayout(4, 4));

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);


* Adds a button to the center panel.
* @param label the button label.
* @param listener the button listener

private void addButton(String label, ActionListener listener)
JButton button = new JButton(label);

* This action insert the button action string to the end of the display text

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);

* This action executes the command that the button action string denotes

private class CommandAction implements ActionListener
public void actionPerformed(ActionEvent event)
String command = event.getActionCommand();

if (command.equals("_"))
start = false;
else lastCommand = command;
lastCommand = command;
start = true;

* Carries out the pending calculation.
* @param X the value to be accumalated with the prior result

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);


i really want to clear this doubt, please help me :(

calculator_UI.jpg254.07 KB

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Joined: 2014-05-16

sorry but surly know about this but till try to find

best online casinos

Joined: 2014-05-12

hey hi V5B,

here's a solution to ur question..........

1) you just have to import a class in imports
import java.applet.*;

2) & then just use extends Applet in below
public class CalculatorPanel extends Applet {
// your code }

it will do it......... :)
i hav added a code with output. see it if u hav problem fell free to ask