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import java.awt.BorderLayout; |
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import java.awt.GridLayout; |
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import java.awt.event.ActionEvent; |
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import java.awt.event.ActionListener; |
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import javax.swing.JButton; |
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import javax.swing.JPanel; |
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import javax.swing.JTextField; |
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|
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/** |
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A component that lets the user enter a number, using |
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a button pad labeled with digits |
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*/ |
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public class KeyPad extends JPanel |
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{ |
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/** |
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Constructs the keypad panel. |
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*/ |
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public KeyPad() |
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{ |
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setLayout(new BorderLayout()); |
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|
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// add display field |
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|
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display = new JTextField(); |
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add(display, "North"); |
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|
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// make button panel |
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|
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buttonPanel = new JPanel(); |
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buttonPanel.setLayout(new GridLayout(4, 3)); |
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|
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// add digit buttons |
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|
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addButton("7"); |
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addButton("8"); |
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addButton("9"); |
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addButton("4"); |
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addButton("5"); |
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addButton("6"); |
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addButton("1"); |
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addButton("2"); |
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addButton("3"); |
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addButton("0"); |
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addButton("."); |
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|
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// add clear entry button |
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|
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clearButton = new JButton("CE"); |
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buttonPanel.add(clearButton); |
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|
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class ClearButtonListener implements ActionListener |
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{ |
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public void actionPerformed(ActionEvent event) |
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{ |
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display.setText(""); |
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} |
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} |
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ActionListener listener = new ClearButtonListener(); |
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|
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clearButton.addActionListener(new |
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ClearButtonListener()); |
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|
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add(buttonPanel, "Center"); |
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} |
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|
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/** |
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Adds a button to the button panel |
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@param label the button label |
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*/ |
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private void addButton(final String label) |
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{ |
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class DigitButtonListener implements ActionListener |
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{ |
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public void actionPerformed(ActionEvent event) |
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{ |
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|
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// don't add two decimal points |
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if (label.equals(".") |
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&& display.getText().indexOf(".") != -1) |
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return; |
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|
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// append label text to button |
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display.setText(display.getText() + label); |
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} |
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} |
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|
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JButton button = new JButton(label); |
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buttonPanel.add(button); |
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ActionListener listener = new DigitButtonListener(); |
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button.addActionListener(listener); |
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} |
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|
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/** |
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Gets the value that the user entered. |
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@return the value in the text field of the keypad |
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*/ |
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public double getValue() |
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{ |
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return Double.parseDouble(display.getText()); |
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} |
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|
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/** |
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Clears the dislay. |
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*/ |
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public void clear() |
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{ |
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display.setText(""); |
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} |
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|
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private JPanel buttonPanel; |
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private JButton clearButton; |
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private JTextField display; |
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} |
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