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Thread: Help with jButton

  1. #1
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    Default Help with jButton

    I've created a calculator. Two .java files, one the calculator, one the GUI.

    I'm stuck on how to link up the jButton ActionListeners.... wondering if anyone can help...

    import javax.swing.*;
    import java.awt.event.*;
     
    public class ButtonDemo extends Calculator{
     
        private JButton btnAdd,  btnMinus,  btnMultiply,  btnDivide,  btnPercent,  btnSqrRoot,  btnTotal,  btnExit;
        private JLabel lblTotal,  lblNumber;
        private JTextField txtTotal,  txtNumber;
        private JPanel panel;
        private JFrame frame;
     
        public ButtonDemo() {
            frame = new JFrame();
            frame.setTitle("Calculator");
            frame.setSize(300, 300);
            frame.setDefaultCloseOperation(frame.EXIT_ON_CLOSE);
     
            panel = new JPanel();
            panel.setLayout(null);
     
            lblTotal = new JLabel("Total");
            lblTotal.setBounds(10, 50, 100, 20);
            panel.add(lblTotal);
     
            txtTotal = new JTextField();
            txtTotal.setBounds(110, 50, 150, 20);
    		txtTotal.addActionListener(new TotalHandler());
            panel.add(txtTotal);
     
            lblNumber = new JLabel("Number");
            lblNumber.setBounds(10, 70, 100, 20);
            panel.add(lblNumber);
     
            txtNumber = new JTextField("");
            txtNumber.setBounds(110, 70, 150, 20);
            panel.add(txtNumber);
     
            btnAdd = new JButton("Add");
            btnAdd.setBounds(50, 110, 100, 20);
            btnAdd.addActionListener(new AddHandler());
            panel.add(btnAdd);
     
            btnMinus = new JButton("Minus");
            btnMinus.setBounds(150, 110, 100, 20);
            btnMinus.addActionListener(new MinusHandler());
            panel.add(btnMinus);
     
            btnMultiply = new JButton("Multiply");
            btnMultiply.setBounds(50, 130, 100, 20);
            btnMultiply.addActionListener(new MultiplyHandler());
            panel.add(btnMultiply);
     
            btnDivide = new JButton("Divide");
            btnDivide.setBounds(150, 130, 100, 20);
            btnDivide.addActionListener(new DivideHandler());
            panel.add(btnDivide);
     
            btnPercent = new JButton("Percent");
            btnPercent.setBounds(50, 150, 100, 20);
            btnPercent.addActionListener(new PercentHandler());
            panel.add(btnPercent);
     
            btnSqrRoot = new JButton("SqrRoot");
            btnSqrRoot.setBounds(150, 150, 100, 20);
            btnSqrRoot.addActionListener(new SqrRootHandler());
            panel.add(btnSqrRoot);
     
            btnTotal = new JButton("Total");
            btnTotal.setBounds(50, 170, 100, 20);
            btnTotal.addActionListener(new TotalHandler());
            panel.add(btnTotal);
     
            btnExit = new JButton("Exit");
            btnExit.setBounds(150, 170, 100, 20);
            btnExit.addActionListener(new ExitHandler());
            panel.add(btnExit);
     
            frame.getContentPane().add(panel);
            frame.setVisible(true);
        }
     
        class TotalHandler implements ActionListener {
            public void actionPerformed(ActionEvent event) {
    			txtTotal.setText(total +  "");
            }
        }
     
        class AddHandler implements ActionListener {
            public void actionPerformed(ActionEvent event) {
    			AddTotal totals = new AddTotal();
     
            }
        }
     
        class MinusHandler implements ActionListener {
            public void actionPerformed(ActionEvent event) {
     
            }
        }
     
        class MultiplyHandler implements ActionListener {
            public void actionPerformed(ActionEvent event) {
     
            }
        }
     
        class DivideHandler implements ActionListener {
            public void actionPerformed(ActionEvent event) {
     
            }
        }
     
        class PercentHandler implements ActionListener {
            public void actionPerformed(ActionEvent event) {
     
            }
        }
     
        class SqrRootHandler implements ActionListener {
            public void actionPerformed(ActionEvent event) {
     
            }
        }
     
         class ExitHandler implements ActionListener {
            public void actionPerformed(ActionEvent event) {
                System.exit(0);
            }
        }
     
     
        public static void main(String[] args) {
           new ButtonDemo();
        }
    }

    import javax.swing.*;
    import java.awt.event.*;
     
    public class ButtonDemo extends Calculator{
     
        private JButton btnAdd,  btnMinus,  btnMultiply,  btnDivide,  btnPercent,  btnSqrRoot,  btnExit;
        private JLabel lblTotal,  lblNumber;
        private JTextField txtTotal,  txtNumber;
        private JPanel panel;
        private JFrame frame;
     
        public ButtonDemo() {
            frame = new JFrame();
            frame.setTitle("Calculator");
            frame.setSize(300, 300);
            frame.setDefaultCloseOperation(frame.EXIT_ON_CLOSE);
     
            panel = new JPanel();
            panel.setLayout(null);
     
            lblTotal = new JLabel("Total");
            lblTotal.setBounds(10, 50, 100, 20);
            panel.add(lblTotal);
     
            txtTotal = new JTextField();
            txtTotal.setBounds(110, 50, 150, 20);
    		txtTotal.addActionListener(new TotalHandler());
            panel.add(txtTotal);
     
            lblNumber = new JLabel("Number");
            lblNumber.setBounds(10, 70, 100, 20);
            panel.add(lblNumber);
     
            txtNumber = new JTextField("");
            txtNumber.setBounds(110, 70, 150, 20);
            panel.add(txtNumber);
     
            btnAdd = new JButton();
            btnAdd.setBounds(50, 110, 100, 20);
            btnAdd.addActionListener(new AddHandler());
            panel.add(btnAdd);
     
            btnMinus = new JButton("Minus");
            btnMinus.setBounds(150, 110, 100, 20);
            btnMinus.addActionListener(new MinusHandler());
            panel.add(btnMinus);
     
            btnMultiply = new JButton("Multiply");
            btnMultiply.setBounds(50, 130, 100, 20);
            btnMultiply.addActionListener(new MultiplyHandler());
            panel.add(btnMultiply);
     
            btnDivide = new JButton("Divide");
            btnDivide.setBounds(150, 130, 100, 20);
            btnDivide.addActionListener(new DivideHandler());
            panel.add(btnDivide);
     
            btnPercent = new JButton("Percent");
            btnPercent.setBounds(50, 150, 100, 20);
            btnPercent.addActionListener(new PercentHandler());
            panel.add(btnPercent);
     
            btnSqrRoot = new JButton("SqrRoot");
            btnSqrRoot.setBounds(150, 150, 100, 20);
            btnSqrRoot.addActionListener(new SqrRootHandler());
            panel.add(btnSqrRoot);
     
            btnExit = new JButton("Exit");
            btnExit.setBounds(100, 170, 100, 20);
            btnExit.addActionListener(new ExitHandler());
            panel.add(btnExit);
     
            frame.getContentPane().add(panel);
            frame.setVisible(true);
        }
     
        class TotalHandler implements ActionListener {
            public void actionPerformed(ActionEvent event) {
    			txtTotal.setText(total +  "");
            }
        }
     
        class AddHandler implements ActionListener {
            public void actionPerformed(ActionEvent event) {
    			!!!!!!STUCK HERE!!!!!! Need to call the 'add()' method from calculator......!!!!
            }
        }
     
        class MinusHandler implements ActionListener {
            public void actionPerformed(ActionEvent event) {
     
            }
        }
     
        class MultiplyHandler implements ActionListener {
            public void actionPerformed(ActionEvent event) {
     
            }
        }
     
        class DivideHandler implements ActionListener {
            public void actionPerformed(ActionEvent event) {
     
            }
        }
     
        class PercentHandler implements ActionListener {
            public void actionPerformed(ActionEvent event) {
     
            }
        }
     
        class SqrRootHandler implements ActionListener {
            public void actionPerformed(ActionEvent event) {
     
            }
        }
     
         class ExitHandler implements ActionListener {
            public void actionPerformed(ActionEvent event) {
                System.exit(0);
            }
        }
     
     
        public static void main(String[] args) {
           new ButtonDemo();
        }
    }
    Last edited by ls7897; March 13th, 2011 at 12:20 PM.


  2. #2
    Super Moderator copeg's Avatar
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    Default Re: Help with jButton

    What do you mean by 'link up'? Do you mean call the methods of Calculator from the action listeners? As ButtonDemo extends Calculator, you can just directly call the method(s), passing entered value from the JTextField (which must first be converted to a primitive - see the API's for the primitive wrappers, for example Double parseDouble() function)

  3. The Following User Says Thank You to copeg For This Useful Post:

    ls7897 (March 13th, 2011)

  4. #3
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    Default Re: Help with jButton

    Quote Originally Posted by copeg View Post
    What do you mean by 'link up'? Do you mean call the methods of Calculator from the action listeners? As ButtonDemo extends Calculator, you can just directly call the method(s), passing entered value from the JTextField (which must first be converted to a primitive - see the API's for the primitive wrappers, for example Double parseDouble() function)
    This is exactly what I mean, but I just can't work out how to do it correctly. I'm getting errors everytime including 'cannot put add(Double) into jButton....

  5. #4
    Super Moderator copeg's Avatar
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    Default Re: Help with jButton

    What have you tried? What exactly are the errors?

  6. #5
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    Default Re: Help with jButton

        class AddHandler implements ActionListener {
            public void actionPerformed(ActionEvent event) {
    			AddTotal totals = new AddTotal();
    			totals.add();
            }
        }

        class AddHandler implements ActionListener {
            public void actionPerformed(ActionEvent event) {
    			txtTotal.add(total);
            }
        }

        class AddHandler implements ActionListener {
            public void actionPerformed(ActionEvent event) {
    			return add();
            }
        }

    I'm really lost!!!!

  7. #6
    mmm.. coffee JavaPF's Avatar
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    Default Re: Help with jButton

    Moved thread to - AWT / Java Swing
    Please use [highlight=Java] code [/highlight] tags when posting your code.
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  8. #7
    Super Moderator copeg's Avatar
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    Default Re: Help with jButton

    Break the problem down into smaller steps 1) get the user entered value - you can use the getText() method to retrieve this from a JTextField 2) Convert that value to something the method you wish to use understands - if you have a String and need to pass a double, you can use Double.parseDouble 3) pass that value to your method(s) - call your method with the value obtained in 2. In the form of the action listener, these steps are written in pseudo-code below.
    public void actionPerformed(ActionEvent e){
      //1
      //2
      //3
    }

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