Java Swing Calculator

by **princeterror** Sat Sep 22, 2012 4:45 am

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Code:: 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<jbnButtons.length; i++) { if(e.getSource() == jbnButtons[i]) { switch(i) { case 0: addDigitToDisplay(i); break; case 1: addDigitToDisplay(i); break; case 2: addDigitToDisplay(i); break; case 3: addDigitToDisplay(i); break; case 4: addDigitToDisplay(i); break; case 5: addDigitToDisplay(i); break; case 6: addDigitToDisplay(i); break; case 7: addDigitToDisplay(i); break; case 8: addDigitToDisplay(i); break; case 9: addDigitToDisplay(i); break; case 10: // +/- processSignChange(); break; case 11: // decimal point addDecimalPoint(); break; case 12: // = processEquals(); break; case 13: // divide processOperator("/"); break; case 14: // * processOperator("*"); break; case 15: // - processOperator("-"); break; case 16: // + processOperator("+"); break; case 17: // sqrt if (displayMode != ERROR_MODE) { try { if (getDisplayString().indexOf("-") == 0) displayError("Invalid input for function!"); result = Math.sqrt(getNumberInDisplay()); displayResult(result); } catch(Exception ex) { displayError("Invalid input for function!"); displayMode = ERROR_MODE; } } break; case 18: // 1/x if (displayMode != ERROR_MODE){ try { if (getNumberInDisplay() == 0) displayError("Cannot divide by zero!"); result = 1 / getNumberInDisplay(); displayResult(result); } catch(Exception ex) { displayError("Cannot divide by zero!"); displayMode = ERROR_MODE; } } break; case 19: // % if (displayMode != ERROR_MODE){ try { result = getNumberInDisplay() / 100; displayResult(result); } catch(Exception ex) { displayError("Invalid input for function!"); displayMode = ERROR_MODE; } } break; case 20: // backspace if (displayMode != ERROR_MODE){ setDisplayString(getDisplayString().substring(0, getDisplayString().length() - 1)); if (getDisplayString().length() < 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(); } }