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t38

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Split a Java Calculator into two seperate classes

hi, i've written the java calculator below as a single class but need to split it into two, one that contiains the gui and one that contains the calculator 'engine' - i'm new to swing and i'm not sure how to split them and get them to interact with one another.  any pointers please?

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


/**
 * A Class that operates as both the framework for a calculator
 * and the calculator engine.
 *
 */
public class CalcFrame

{
   // private CalcEngine calc;

    private JFrame frame;
    private JTextField display;
    private JLabel status;

    //declare all buttons
    private JButton zeroButton = new JButton("0");
    private JButton oneButton = new JButton("1");
    private JButton twoButton = new JButton("2");
    private JButton threeButton = new JButton("3");
    private JButton fourButton = new JButton("4");
    private JButton fiveButton = new JButton("5");
    private JButton sixButton = new JButton("6");
    private JButton sevenButton = new JButton("7");
    private JButton eightButton = new JButton("8");
    private JButton nineButton = new JButton("9");
    private JButton plusButton = new JButton("+");
    private JButton minusButton = new JButton("-");
    private JButton divideButton = new JButton("/");
    private JButton multiplyButton = new JButton("*");
    private JButton equalsButton = new JButton("=");
    private JButton cancelButton = new JButton("C");


    private String lastNumberEntered;
    private String lastOperatorEntered;


    public CalcFrame()//CalcEngine engine)
    {

        //frame.setVisible(true);
       // calc = engine;
        makeFrame();
   
    /**
     * When an button is pressed perform that action
     */
   
   
        zeroButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                addToDisplay("0");
            }
        });

        oneButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                addToDisplay("1");
            }
        });


        twoButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                addToDisplay("2");
            }
        });
       
        threeButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                addToDisplay("3");
            }
        });
       
        fourButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                addToDisplay("4");
            }
        });
       
        fiveButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                addToDisplay("5");
            }
        });
       
        sixButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                addToDisplay("6");
            }
        });
       
        sevenButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                addToDisplay("7");
            }
        });
       
        eightButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                addToDisplay("8");
            }
        });
       
        nineButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                addToDisplay("9");
            }
        });
        plusButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                addToDisplay("+");
            }
        });
       
        minusButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                addToDisplay("-");
            }
        });
       
        divideButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                addToDisplay("/");
            }
        });
       
        multiplyButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                addToDisplay("*");
            }
        });
       
        equalsButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                float calculation = performCalculation(lastNumberEntered, display.getText(),lastOperatorEntered);
                display.setText(calculation + "");
               
                //http://java.sun.com/docs/books/tutorial/java/data/converting.html
            }
        });

        cancelButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                display.setText("");
                lastNumberEntered = null;
                lastOperatorEntered = null;
            }
        });

    }

    /**
     * This allows you to quit the calculator.
     */

    // Alows the class to quit.
    private void quit() {
        System.exit(0);


    }

    private void addToDisplay(String displayCharacter) {
        if (isAnOperator(displayCharacter)) {//if an operator is pressed, save the current number then display operator
            lastNumberEntered = display.getText();
            display.setText(displayCharacter);
            lastOperatorEntered = displayCharacter;
            //need to save what the display had here
        } else {
            if (isAnOperator(display.getText())) {//if display is an operator add a new number
                display.setText(displayCharacter);
            } else {
                display.setText(display.getText() + displayCharacter);//append displayCharacter to display
            }
        }
    }

    private float performCalculation(String firstNumberString, String secondNumberString, String operator) {
        //http://java.sun.com/docs/books/tutorial/java/data/converting.html
        float firstNumber = Float.valueOf(firstNumberString);
        float secondNumber = Float.valueOf(secondNumberString);
        if (operator.equals("+")) {
            return firstNumber + secondNumber;
        } else if (operator.equals("-")) {
            return firstNumber - secondNumber;
        } else if (operator.equals("*")) {
            return firstNumber * secondNumber;
        } else if (operator.equals("/")) {
            return firstNumber / secondNumber;
        } else {
            return -1;
        }
    }

    /**
     * Check if an input is an operator
     *
     * @return true if +,-,* or /
     */
    private boolean isAnOperator(String input) {
        if (input.equals("+") || input.equals("-") || input.equals("/") || input.equals("*")) {
            return true;
        }
        else return false;
    }

    // Calls the dialog frame with the information about the project.

    private void showAbout() {
        JOptionPane.showMessageDialog(frame,
                "Java Calculator Group Project 2011",
                "About Calculator Group Project",
                JOptionPane.INFORMATION_MESSAGE);
    }


   
    /**
     * The following creates a layout of the calculator frame.
     */
    private void makeFrame() {
        frame = new JFrame("Group Project Calculator");
        makeMenuBar(frame);

        JPanel contentPane = (JPanel) frame.getContentPane();
        contentPane.setLayout(new BorderLayout(8, 8));
        contentPane.setBorder(new EmptyBorder(10, 10, 10, 10));


        /**
         * Insert a text field
         */
        display = new JTextField("0");
        contentPane.add(display, BorderLayout.NORTH);

        //Container contentPane = frame.getContentPane();
        contentPane.setLayout(new GridLayout(4, 4));
        JPanel buttonPanel = new JPanel(new GridLayout(4, 4));
        contentPane.add(zeroButton);
        contentPane.add(oneButton);
        contentPane.add(twoButton);
        contentPane.add(threeButton);
        contentPane.add(fourButton);
        contentPane.add(fiveButton);
        contentPane.add(sixButton);
        contentPane.add(sevenButton);
        contentPane.add(eightButton);
        contentPane.add(nineButton);
        contentPane.add(plusButton);
        contentPane.add(minusButton);
        contentPane.add(divideButton);
        contentPane.add(multiplyButton);
        contentPane.add(equalsButton);
        contentPane.add(cancelButton);

        contentPane.add(buttonPanel, BorderLayout.CENTER);

       
        //contentPane.add(status, BorderLayout.SOUTH);

        frame.pack();
        frame.setVisible(true);
    }

    /**
     * Create the main frame's menu bar.
     * The frame that the menu bar should be added to.
     */
    private void makeMenuBar(JFrame frame) {
        final int SHORTCUT_MASK =
        Toolkit.getDefaultToolkit().getMenuShortcutKeyMask();


        JMenuBar menubar = new JMenuBar();
        frame.setJMenuBar(menubar);

        JMenu menu;
        JMenuItem item;

        // create the File menu
        menu = new JMenu("File");
        menubar.add(menu);

        // create the Quit menu with a shortcut "Q" key.
        item = new JMenuItem("Quit");
        item.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_Q, SHORTCUT_MASK));
        item.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                quit();
            }
        });
       
        menu.add(item);

        // Adds an about menu.
        menu = new JMenu("About");
        menubar.add(menu);

        // Displays
        item = new JMenuItem("Calculator Project");
        item.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                showAbout();
            }
        });
        menu.add(item);

    }


    public static void main(String[] args) {
       
    }

}
SOLUTION
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for_yan
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Try looking at some patterns...

For a calculator you could consider an MVC pattern (http://en.wikipedia.org/wiki/Model%E2%80%93View%E2%80%93Controller).

Your View is the for you want users to manipulate
Your Model does all the calculations and creates events with results
Your Controller defines all your user interaction. I believe, you could combine Model and Controller into a single class and once your computations is complete, simply update your form with required information.

Hope this will get you started... If you have any problems, let me know and I'll try to find some examples of this pattern for you.
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SOLUTION
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Avatar of t38
t38

ASKER

thanks, i'm going to work on this today and will report back.