Calculator.java

/*
    Participation #8: Java Calculator
    Programmer:
    Date:       December 1st,2015
    Filename:   Calculator.java
    Purpose:    This program creates a calculator with a menu.
*/

import java.awt.*;
import java.awt.event.*;
import java.awt.event.*;
import java.text.DecimalFormat;
import javax.swing.JOptionPane;

public class Calculator extends Frame implements ActionListener
{
    private Button keys[];
    private Panel keypad;
    private TextField lcd;
    private double op1;
    private boolean first;
    private boolean foundKey;
    private boolean clearText;
    private int last0p;
    private DecimalFormat calcPattern;

    public Calculator()
    {
        //create an instance of the menu//
        MenuBar mnuBar = new MenuBar();
        setMenuBar(mnuBar);

        //construct a populate the file menu//
        Menu mnuFile = new Menu("File", true);
        mnuBar.add(mnuFile);
            MenuItem mnuFileExit = new MenuItem("Exit");
            mnuFile.add(mnuFileExit);

        //construct and populate the Edit menu//
        Menu mnuEdit = new Menu("Edit",true);
        mnuBar.add(mnuEdit);
            MenuItem mnuEditClear = new MenuItem("Clear");
            mnuEdit.add(mnuEditClear);
            mnuEdit.insertSeparator(1);
            MenuItem mnuEditCopy = new MenuItem("Copy");
            mnuEdit.add(mnuEditCopy);
            MenuItem mnuEditPaste = new MenuItem("Paste");
            mnuEdit.add(mnuEditPaste);

        //construct and populate the about menu
        Menu mnuAbout = new Menu("About",true);
            mnuBar.add(mnuAbout);
            MenuItem mnuAboutCalculator = new MenuItem("About Calculator");
            mnuAbout.add(mnuAboutCalculator);

            //add the ActionListener to each menu item
            mnuFileExit.addActionListener(this);
            mnuEditClear.addActionListener(this);
            mnuEditCopy.addActionListener(this);
            mnuEditPaste.addActionListener(this);
            mnuAboutCalculator.addActionListener(this);

            //assign an actionComant to each menu item
            mnuFileExit.setActionCommand("Exit");
            mnuEditClear.setActionCommand("Clear");
            mnuEditCopy.setActionCommand("Copy");
            mnuEditPaste.setActionCommand("Paste");
            mnuAboutCalculator.setActionCommand("About");

            //construct components and initialize beiginning values
            lcd = new TextField(20);
                lcd.setEditable(false);
            keypad = new Panel();
            keys = new Button[16];
            first = true;
            op1 = 0.0;
            clearText = true;
            last0p = 0;
            calcPattern = new DecimalFormat("########.########");

            //construct and assign captions to the buttons
            for (int i=0; i<=9; i++)
                keys[i] = new Button(String.valueOf(i));

            keys[10] = new Button("/");
            keys[11] = new Button("*");
            keys[12] = new Button("-");
            keys[13] = new Button("+");
            keys[14] = new Button("=");
            keys[15] = new Button(".");

            //set Frame and keypad layout to grid layout
            setLayout(new BorderLayout());
            keypad.setLayout(new GridLayout(4,4,10,10));

            for (int i=7; i<=10; i++) //7,8,9 divide
                keypad.add(keys[i]);

            for (int i=4; i<=6; i++)
                keypad.add(keys[i]);

            keypad.add(keys[11]); // multiply

            for (int i=1; i<=3; i++) //1,2,3
                keypad.add(keys[i]);

            keypad.add(keys[12]); //subtract

            keypad.add(keys[0]); //key

            for (int i=15; i>=13; i--)
                keypad.add(keys[i]);  //decimal point, =, add(+) keys

            for (int i=0; i<keys.length; i++)
                keys[i].addActionListener(this);

            add(lcd, BorderLayout.NORTH);
            add(keypad, BorderLayout.CENTER);

                    addWindowListener(
                        new WindowAdapter()
                        {
                            public void windowClosing(WindowEvent e)
                            {
                                System.exit(0);
                            }
                        }

                    );
                }//end of constructor method

    public void actionPerformed(ActionEvent e)
    {
            //test for menu item clicks//
            String arg = e.getActionCommand();
            if (arg == "Exit")
                System.exit(0);

            if(arg == "Clear")
            {
                    clearText = true;
                    first = true;
                    op1 = 0.0;
                    lcd.setText("");
                    lcd.requestFocus();
                }

            if (arg == "Copy")
            {
                Clipboard cb = Toolkit.getDefaultToolkit().getSystemClipboard();
                StringSelection contents = new StringSelection(lcd.getText());
                cb.setContents(contents,null);
            }

            if (arg =="Paste")
            {
                Clipboard cb = Toolkit.getDefaultToolkit().getSystemClipboard();
                Transferable content = cb.getContents(this);
                try
                {
                    String s = (String)content.getTransferData(DataFlavor.stringFlavor);
                    lcd.setText(calcPattern.format(Double.parseDouble(s)));
                }
                catch (Throwable exc)
                {
                    lcd.setText("");
                }
            }

            if(arg =="About")
            {
                String message = "Calculator ver. 1.0\nOpenExhibit Software\nCopyright 2007\nAll rights reserved";
                JOptionPane.showMessageDialog(null,message,"About Calculator", JOptionPane.INFORMATION_MESSAGE);
            }

            //test for button clicks
            foundKey = false;

            //search for clicked key
            for (int i=0; i<keys.length && !foundKey; i++)
            {
                if(e.getSource() == keys[i])
                {
                    foundKey = true;
                    switch(i)
                    {
                        //number and decimal point buttons
                        case 0: case 1:  case 2 :case 3 :case 4: case 5: case 6: case 7: case 8: case 9: case 15:
                            if(clearText)
                            {
                                lcd.setText("");
                                clearText = false;
                            }
                            lcd.setText(lcd.getText() + keys[i].getLabel());
                            break;

                            //operator buttons
                            case 10: case 11: case 12: case 13: case 14:
                                clearText = true;

                                if (first) //first operand
                                {
                                    if(lcd.getText().length()==0) op1=0.0;
                                    else op1 = Double.parseDouble(lcd.getText());

                                    first = false;
                                    clearText = true;
                                    last0p = i;  // save last operator
                                }
                                    else //second operand
                                    {
                                        switch(last0p)
                                        {
                                            case 10: //divide button
                                                op1 /= Double.parseDouble(lcd.getText());
                                                break;
                                            case 11: //multiply button
                                                op1 *= Double.parseDouble(lcd.getText());
                                                break;
                                            case 12: //minus button
                                                op1 -= Double.parseDouble(lcd.getText());
                                                break;
                                            case 13: //plus button
                                                op1 += Double.parseDouble(lcd.getText());
                                                break;
                                            } //end of switch (last0p)
                                            lcd.setText(calcPattern.format(op1));
                                            clearText=true;

                                            if(i==14) first = true; //equal button
                                            else last0p = i; // save last operator
                                        } //end else
                                        break;
                                    } //end of switch(i)
                                } //end of it
                            }//end of for
                        } //end of actionPerformed

                        public static void main(String args[])
                        {
                            //set frame properties
                            Calculator f = new Calculator();
                            f.setTitle("Calculator Application");
                            f.setBounds(200,200,300,300);
                            f.setVisible(true);

                            //set image properties and add to frame
                            Image icon = Toolkit.getDefaultToolkit().getImage("calcImage.gif");
                            f.setIconImage(icon);

                        } //end of main
                    }// end of class