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Thread: Is this correct.Am I close? Help please

  1. #1
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    Default Is this correct.Am I close? Help please

    Current problem only includes addition function. Here is what i did..is this correct for my problem where I need to modify it to include buttons and calculation for multiplication,division and subtraction.?

    import java.awt.event.ActionEvent;
    import java.awt.event.ActionListener;
     
    import javax.swing.JButton;
    import javax.swing.JFrame;
    import javax.swing.JPanel;
    import javax.swing.JTextField;
     
    public class BasicCalculator {
    private static final int FRAME_WIDTH = 150;
    private static final int FRAME_HEIGHT = 120;
     
    // Keeps track of the current operation (subtract, add, etc)
    private static final int NO_OPERATION = 0;
    private static final int ADDITION = 1;
    public static int operation = NO_OPERATION;
     
    public static JTextField textFieldDisplay;
    public static double Value1 = 0; // holds the value before the operation
     
    public static void main(String[] args) {
    // Set up the user interface
    JFrame frame = new JFrame();
    JPanel buttonPanel = new JPanel();
    frame.add(buttonPanel);
     
    // create two buttons, plus and equal and a text box for answers
    textFieldDisplay = new JTextField(10);
    buttonPanel.add(textFieldDisplay);
    JButton buttonPlus = new JButton(" + ");
    buttonPanel.add(buttonPlus);
    JButton buttonEqual = new JButton(" = ");
    buttonPanel.add(buttonEqual);
     
    frame.setSize(FRAME_WIDTH, FRAME_HEIGHT);
    frame.setTitle("Basic Calculator");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOS E);
    frame.setVisible(true);
     
     
    // called when the equal sign '=' is pressed
    class EqualSignListener implements ActionListener {
     
    public void actionPerformed(ActionEvent event)
    {
    double Value2 = Double.parseDouble(textFieldDisplay.getText());
    if (operation == ADDITION) {
    // plus sign pressed before the equal sign
    Value2 += Value1;
    }
    // Convert from a answer to a string
    Double answer = new Double(Value2);
    textFieldDisplay.setText( answer.toString() );
    // Reset the operation to show no current operation
    operation = NO_OPERATION;
    }
    }
     
    // called when a plus sign '+' is pressed
    class PlusSignListener implements ActionListener {
    public void actionPerformed(ActionEvent event)
    {
    Value1 = Double.parseDouble(textFieldDisplay.getText());
    operation = ADDITION;
    }
    }
     
    // Add the methods that will be called when these buttons are pressed
    ActionListener plusSignListener = new PlusSignListener();
    buttonPlus.addActionListener(plusSignListener);
     
    ActionListener equalSignListener = new EqualSignListener();
    buttonEqual.addActionListener(equalSignListener);
     
    }
    }
    // called when a subtraction sign '-' is pressed
    class SubtractionSignListener implements ActionListener {
    public void actionPerformed(ActionEvent event)
    {
    Value1 = Double.parseDouble(textFieldDisplay.getText());
    operation = Subtraction;
    }
    }
     
    // Add the methods that will be called when these buttons are pressed
    ActionListener subtractionSignListener = new SubtractionSignListener();
    buttonPlus.addActionListener(subtractionSignListen er);
     
    ActionListener equalSignListener = new EqualSignListener();
    buttonEqual.addActionListener(equalSignListener);
    }
    )
    // called when a division sign '/' is pressed
    class DivisionSignListener implements ActionListener {
    public void actionPerformed(ActionEvent event)
    {
    Value1 = Double.parseDouble(textFieldDisplay.getText());
    operation = DIVISION;
    }
    }
     
    // Add the methods that will be called when these buttons are pressed
    ActionListener divisionSignListener = new DivisionSignListener();
    buttonPlus.addActionListener(plusSignListener);
     
    ActionListener equalSignListener = new EqualSignListener();
    buttonEqual.addActionListener(equalSignListener);
    }
    ) 
    // called when a plus sign '*' is pressed
    class MulitplicationSignListener implements ActionListener {
    public void actionPerformed(ActionEvent event)
    {
    Value1 = Double.parseDouble(textFieldDisplay.getText());
    operation = Multiplication;
    }
    }
     
    // Add the methods that will be called when these buttons are pressed
    ActionListener multiplicationSignListener = new MultiplicationSignListener();
    buttonPlus.addActionListener(plusSignListener);
     
    ActionListener equalSignListener = new EqualSignListener();
    buttonEqual.addActionListener(equalSignListener);
     
    }
    }


  2. #2
    Super Moderator Norm's Avatar
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    Default Is this a duplicate of another thread?

    Is this thread the same as: Problem understanding Java code modification

    Please only use one thread for a problem.

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