របៀបបង្កើតម៉ាស៊ីនគិតលេខជាមួយកម្មវិធី ភាសាចាវា How to create simple Calculator with Java Programming Language

Java Calculator Source Code

Oct 15, 2006 by Hemanth

/*
 Name: Hemanth. B
 Website: wwww.java-swing-tutorial.html
 Topic: A basic Java Swing Calculator
 Conventions Used in Source code

 ---------------------------------

 1. All JLabel components start with jlb*

 2. All JPanel components start with jpl*

 3. All JMenu components start with jmenu*

 4. All JMenuItem components start with jmenuItem*

 5. All JDialog components start with jdlg*

 6. All JButton components start with jbn*

 */
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.Window;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.KeyStroke;

public class Calculator extends JFrame implements ActionListener {

 // Variables
 final int MAX_INPUT_LENGTH = 20;
 final int INPUT_MODE = 0;
 final int RESULT_MODE = 1;
 final int ERROR_MODE = 2;
 int displayMode;
 boolean clearOnNextDigit, percent;
 double lastNumber;
 String lastOperator;
 private JMenu jmenuFile, jmenuHelp;
 private JMenuItem jmenuitemExit, jmenuitemAbout;
 private JLabel jlbOutput;
 private JButton jbnButtons[];
 private JPanel jplMaster, jplBackSpace, jplControl;
 /*

  * Font(String name, int style, int size)

  Creates a new Font from the specified name, style and point size.

  */
 Font f12 = new Font("Times New Roman", 0, 12);
 Font f121 = new Font("Times New Roman", 1, 12);
 // Constructor
 public Calculator() {
  /* Set Up the JMenuBar.

   * Have Provided All JMenu's with Mnemonics

   * Have Provided some JMenuItem components with Keyboard Accelerators

   */
  jmenuFile = new JMenu("File");
  jmenuFile.setFont(f121);
  jmenuFile.setMnemonic(KeyEvent.VK_F);
  jmenuitemExit = new JMenuItem("Exit");
  jmenuitemExit.setFont(f12);
  jmenuitemExit.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_X,
    ActionEvent.CTRL_MASK));
  jmenuFile.add(jmenuitemExit);
  jmenuHelp = new JMenu("Help");
  jmenuHelp.setFont(f121);
  jmenuHelp.setMnemonic(KeyEvent.VK_H);
  jmenuitemAbout = new JMenuItem("About Calculator");
  jmenuitemAbout.setFont(f12);
  jmenuHelp.add(jmenuitemAbout);
  JMenuBar mb = new JMenuBar();
  mb.add(jmenuFile);
  mb.add(jmenuHelp);
  setJMenuBar(mb);
  //Set frame layout manager
  setBackground(Color.gray);
  jplMaster = new JPanel();
  jlbOutput = new JLabel("0");
  jlbOutput.setHorizontalTextPosition(JLabel.RIGHT);
  jlbOutput.setBackground(Color.WHITE);
  jlbOutput.setOpaque(true);
  // Add components to frame
  getContentPane().add(jlbOutput, BorderLayout.NORTH);
  jbnButtons = new JButton[23];
  //  GridLayout(int rows, int cols, int hgap, int vgap)
  JPanel jplButtons = new JPanel(); // container for Jbuttons
  // Create numeric Jbuttons
  for (int i = 0; i <= 9; i++) {
   // set each Jbutton label to the value of index
   jbnButtons[i] = new JButton(String.valueOf(i));
  }
  // Create operator Jbuttons
  jbnButtons[10] = new JButton("+/-");
  jbnButtons[11] = new JButton(".");
  jbnButtons[12] = new JButton("=");
  jbnButtons[13] = new JButton("/");
  jbnButtons[14] = new JButton("*");
  jbnButtons[15] = new JButton("-");
  jbnButtons[16] = new JButton("+");
  jbnButtons[17] = new JButton("sqrt");
  jbnButtons[18] = new JButton("1/x");
  jbnButtons[19] = new JButton("%");
  jplBackSpace = new JPanel();
  jplBackSpace.setLayout(new GridLayout(1, 1, 2, 2));
  jbnButtons[20] = new JButton("Backspace");
  jplBackSpace.add(jbnButtons[20]);
  jplControl = new JPanel();
  jplControl.setLayout(new GridLayout(1, 2, 2, 2));
  jbnButtons[21] = new JButton(" CE ");
  jbnButtons[22] = new JButton("C");
  jplControl.add(jbnButtons[21]);
  jplControl.add(jbnButtons[22]);
  //  Setting all Numbered JButton's to Blue. The rest to Red
  for (int i = 0; i < jbnButtons.length; i++) {
   jbnButtons[i].setFont(f12);
   if (i < 10)
    jbnButtons[i].setForeground(Color.blue);
   else
    jbnButtons[i].setForeground(Color.red);
  }
  // Set panel layout manager for a 4 by 5 grid
  jplButtons.setLayout(new GridLayout(4, 5, 2, 2));
  //Add buttons to keypad panel starting at top left
  // First row
  for (int i = 7; i <= 9; i++) {
   jplButtons.add(jbnButtons[i]);
  }
  // add button / and sqrt
  jplButtons.add(jbnButtons[13]);
  jplButtons.add(jbnButtons[17]);
  // Second row
  for (int i = 4; i <= 6; i++) {
   jplButtons.add(jbnButtons[i]);
  }
  // add button * and x^2
  jplButtons.add(jbnButtons[14]);
  jplButtons.add(jbnButtons[18]);
  // Third row
  for (int i = 1; i <= 3; i++) {
   jplButtons.add(jbnButtons[i]);
  }
  //adds button - and %
  jplButtons.add(jbnButtons[15]);
  jplButtons.add(jbnButtons[19]);
  //Fourth Row
  // add 0, +/-, ., +, and =
  jplButtons.add(jbnButtons[0]);
  jplButtons.add(jbnButtons[10]);
  jplButtons.add(jbnButtons[11]);
  jplButtons.add(jbnButtons[16]);
  jplButtons.add(jbnButtons[12]);
  jplMaster.setLayout(new BorderLayout());
  jplMaster.add(jplBackSpace, BorderLayout.WEST);
  jplMaster.add(jplControl, BorderLayout.EAST);
  jplMaster.add(jplButtons, BorderLayout.SOUTH);
  // Add components to frame
  getContentPane().add(jplMaster, BorderLayout.SOUTH);
  requestFocus();
  //activate ActionListener
  for (int i = 0; i < jbnButtons.length; i++) {
   jbnButtons[i].addActionListener(this);
  }
  jmenuitemAbout.addActionListener(this);
  jmenuitemExit.addActionListener(this);
  clearAll();
  //add WindowListener for closing frame and ending program
  addWindowListener(new WindowAdapter() {

   public void windowClosed(WindowEvent e) {
    System.exit(0);
   }
  });
 } //End of Contructor Calculator
 // Perform action
public void actionPerformed(ActionEvent e){

  double result = 0;

  if(e.getSource() == jmenuitemAbout){

    JDialog dlgAbout = new CustomABOUTDialog(this, 

  "About Java Swing Calculator", true);

   dlgAbout.setVisible(true);

  }else if(e.getSource() == jmenuitemExit){

   System.exit(0);

  } 

 // Search for the button pressed until end of array or key found

  for (int i=0; i< 1)

        setDisplayString("0");

      }

      break;

     case 21: // CE

      clearExisting();

      break;

     case 22: // C

      clearAll();

      break;

    }

   }

  }

 } void setDisplayString(String s) {
  jlbOutput.setText(s);
 }
 String getDisplayString() {
  return jlbOutput.getText();
 }
 void addDigitToDisplay(int digit) {
  if (clearOnNextDigit)
   setDisplayString("");
  String inputString = getDisplayString();
  if (inputString.indexOf("0") == 0) {
   inputString = inputString.substring(1);
  }
  if ((!inputString.equals("0") || digit > 0)
    && inputString.length() < MAX_INPUT_LENGTH) {
   setDisplayString(inputString + digit);
  }
  displayMode = INPUT_MODE;
  clearOnNextDigit = false;
 }
 void addDecimalPoint() {
  displayMode = INPUT_MODE;
  if (clearOnNextDigit)
   setDisplayString("");
  String inputString = getDisplayString();
  // If the input string already contains a decimal point, don't
  //  do anything to it.
  if (inputString.indexOf(".") < 0)
   setDisplayString(new String(inputString + "."));
 }
 void processSignChange() {
  if (displayMode == INPUT_MODE) {
   String input = getDisplayString();
   if (input.length() > 0 && !input.equals("0")) {
    if (input.indexOf("-") == 0)
     setDisplayString(input.substring(1));
    else
     setDisplayString("-" + input);
   }
  } else if (displayMode == RESULT_MODE) {
   double numberInDisplay = getNumberInDisplay();
   if (numberInDisplay != 0)
    displayResult(-numberInDisplay);
  }
 }
 void clearAll() {
  setDisplayString("0");
  lastOperator = "0";
  lastNumber = 0;
  displayMode = INPUT_MODE;
  clearOnNextDigit = true;
 }
 void clearExisting() {
  setDisplayString("0");
  clearOnNextDigit = true;
  displayMode = INPUT_MODE;
 }
 double getNumberInDisplay() {
  String input = jlbOutput.getText();
  return Double.parseDouble(input);
 }
 void processOperator(String op) {
  if (displayMode != ERROR_MODE) {
   double numberInDisplay = getNumberInDisplay();
   if (!lastOperator.equals("0")) {
    try {
     double result = processLastOperator();
     displayResult(result);
     lastNumber = result;
    } catch (DivideByZeroException e) {
    }
   } else {
    lastNumber = numberInDisplay;
   }
   clearOnNextDigit = true;
   lastOperator = op;
  }
 }
 void processEquals() {
  double result = 0;
  if (displayMode != ERROR_MODE) {
   try {
    result = processLastOperator();
    displayResult(result);
   } catch (DivideByZeroException e) {
    displayError("Cannot divide by zero!");
   }
   lastOperator = "0";
  }
 }
 double processLastOperator() throws DivideByZeroException {
  double result = 0;
  double numberInDisplay = getNumberInDisplay();
  if (lastOperator.equals("/")) {
   if (numberInDisplay == 0)
    throw (new DivideByZeroException());
   result = lastNumber / numberInDisplay;
  }
  if (lastOperator.equals("*"))
   result = lastNumber * numberInDisplay;
  if (lastOperator.equals("-"))
   result = lastNumber - numberInDisplay;
  if (lastOperator.equals("+"))
   result = lastNumber + numberInDisplay;
  return result;
 }
 void displayResult(double result) {
  setDisplayString(Double.toString(result));
  lastNumber = result;
  displayMode = RESULT_MODE;
  clearOnNextDigit = true;
 }
 void displayError(String errorMessage) {
  setDisplayString(errorMessage);
  lastNumber = 0;
  displayMode = ERROR_MODE;
  clearOnNextDigit = true;
 }
 public static void main(String args[]) {
  Calculator calci = new Calculator();
  Container contentPane = calci.getContentPane();
  //  contentPane.setLayout(new BorderLayout());
  calci.setTitle("Java Swing Calculator");
  calci.setSize(241, 217);
  calci.pack();
  calci.setLocation(400, 250);
  calci.setVisible(true);
  calci.setResizable(false);
 }
} //End of Swing Calculator Class.

class DivideByZeroException extends Exception {

 public DivideByZeroException() {
  super();
 }
 public DivideByZeroException(String s) {
  super(s);
 }
}

class CustomABOUTDialog extends JDialog implements ActionListener {

 JButton jbnOk;
 CustomABOUTDialog(JFrame parent, String title, boolean modal) {
  super(parent, title, modal);
  setBackground(Color.black);
  JPanel p1 = new JPanel(new FlowLayout(FlowLayout.CENTER));
  StringBuffer text = new StringBuffer();
  text.append("Calculator Information\n\n");
  text.append("Developer: Hemanth\n");
  text.append("Version: 1.0");
  JTextArea jtAreaAbout = new JTextArea(5, 21);
  jtAreaAbout.setText(text.toString());
  jtAreaAbout.setFont(new Font("Times New Roman", 1, 13));
  jtAreaAbout.setEditable(false);
  p1.add(jtAreaAbout);
  p1.setBackground(Color.red);
  getContentPane().add(p1, BorderLayout.CENTER);
  JPanel p2 = new JPanel(new FlowLayout(FlowLayout.CENTER));
  jbnOk = new JButton(" OK ");
  jbnOk.addActionListener(this);
  p2.add(jbnOk);
  getContentPane().add(p2, BorderLayout.SOUTH);
  setLocation(408, 270);
  setResizable(false);
  addWindowListener(new WindowAdapter() {

   public void windowClosing(WindowEvent e) {
    Window aboutDialog = e.getWindow();
    aboutDialog.dispose();
   }
  });
  pack();
 }
 public void actionPerformed(ActionEvent e) {
  if (e.getSource() == jbnOk) {
   this.dispose();
  }
 }
}

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