package listener; import java.awt.BorderLayout; import java.awt.Color; import java.awt.Component; import java.awt.Dimension; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.ItemEvent; import java.awt.event.ItemListener; import java.awt.event.MouseAdapter; import java.awt.event.MouseEvent; import java.awt.event.MouseListener; import javax.swing.Box; import javax.swing.BoxLayout; import javax.swing.JButton; import javax.swing.JCheckBox; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JOptionPane; import javax.swing.JPanel; import javax.swing.JPasswordField; import javax.swing.JTextField; import javax.swing.border.EtchedBorder; public class ListenerInnerClass { // Static variable that the whole class can access. private static JLabel messageLabel = new JLabel("This is a message label"); public static void main(String[] args) { JFrame frame = new JFrame("Demo of Anonymous Inner Class for Listener"); frame.setLocationRelativeTo(null); frame.setLayout(new BorderLayout()); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); placeComponents(frame); frame.pack(); frame.setVisible(true); } private static void placeComponents(JFrame frame) { frame.setLayout(new BorderLayout()); // Overall Panel JPanel framePanel = new JPanel(new BorderLayout()); framePanel.setAlignmentX(Component.RIGHT_ALIGNMENT); // Panel for User Input Area JPanel dataEntryArea = new JPanel(); dataEntryArea.setLayout(new BoxLayout(dataEntryArea, BoxLayout.X_AXIS)); dataEntryArea.setBorder(new EtchedBorder()); dataEntryArea.setToolTipText("This is where you enter your information"); dataEntryArea.setAlignmentX(Component.RIGHT_ALIGNMENT); // SubPanel for Labels Box labelPanel = Box.createVerticalBox(); Box userBox = Box.createHorizontalBox(); JLabel userLabel = new JLabel("User: "); userBox.add(Box.createRigidArea(new Dimension(5,0))); // 5 pixel left padding userBox.add(Box.createHorizontalGlue()); // to force right alignment userBox.add(userLabel); Box passwordBox = Box.createHorizontalBox(); JLabel passwordLabel = new JLabel("Password: "); passwordBox.add(Box.createRigidArea(new Dimension(5,0))); // 5 pixel left padding passwordBox.add(Box.createHorizontalGlue()); // to force right alignment passwordBox.add(passwordLabel); labelPanel.add(Box.createRigidArea(new Dimension(0,5))); // Add 5 px vertical padding labelPanel.add(userBox); labelPanel.add(Box.createRigidArea(new Dimension(0,5))); // Add 5 px vertical padding labelPanel.add(passwordBox); labelPanel.add(Box.createRigidArea(new Dimension(0,5))); // Add 5 px vertical padding // SubPanel for Text Fields Box fieldPanel = Box.createVerticalBox();; JTextField userText = new JTextField(20); JPasswordField passwordText = new JPasswordField(20); fieldPanel.add(Box.createRigidArea(new Dimension(0,5))); // Add 5 px vertical padding fieldPanel.add(userText); fieldPanel.add(Box.createRigidArea(new Dimension(0,5))); // Add 5 px vertical padding fieldPanel.add(passwordText); fieldPanel.add(Box.createRigidArea(new Dimension(0,5))); // Add 5 px vertical padding // Use East and West of userInputArea dataEntryArea.add(labelPanel, BorderLayout.WEST); dataEntryArea.add(fieldPanel, BorderLayout.CENTER); // Why the center, rather than EAST? // *** This becomes the North panel of the frame framePanel.add(dataEntryArea, BorderLayout.NORTH); JCheckBox chkMember = new JCheckBox("Member?"); JButton loginButton = new JButton("login"); JButton registerButton = new JButton("register"); JButton helpButton = new JButton("help"); JButton rightClickButton = new JButton("right, left or center click me"); JButton doubleClickButton = new JButton("double click me"); // Boxes are like JPanels with a Box Layout Box buttonArea = new Box(BoxLayout.X_AXIS); buttonArea.add(Box.createHorizontalGlue()); // Horizontal glue on each side will center! buttonArea.add(loginButton); buttonArea.add(registerButton); buttonArea.add(Box.createRigidArea(new Dimension(30, 0))); // spaces Help button out buttonArea.add(helpButton); buttonArea.add(rightClickButton); buttonArea.add(doubleClickButton); buttonArea.add(chkMember); buttonArea.add(Box.createHorizontalGlue()); // Horizontal glue on each side will center! // *** This becomes the South panel of the frame framePanel.add(buttonArea, BorderLayout.SOUTH); // Throw our special message in the East of the frame framePanel.add(messageLabel, BorderLayout.EAST); // Finally add the framePanel to the frame frame.add(framePanel); /* ****************************************************** * Here is the anonymous inner class. It is anonymous * because it does not have a class header. * * Why not name this inner class? * - We only need to use the inner class once, so * the class body (i.e., the overloaded method) * will only appear once. * * - If we planned on creating multiple instances * of an inner class, where we wanted to reuse * the class body, we should name the class so * we don't have to always specify the class body. */ ActionListener myButtonListener = new ActionListener() { @Override public void actionPerformed(ActionEvent e) { JButton source = (JButton) e.getSource(); JOptionPane.showMessageDialog(source, source.getText() + " button has been pressed"); } }; ActionListener myCheckboxActionListener = new ActionListener() { @Override public void actionPerformed(ActionEvent e) { JOptionPane.showMessageDialog( null, "The source is " + e.getSource(), "Action Listener fired", JOptionPane.INFORMATION_MESSAGE); } }; ItemListener myCheckboxItemListener = new ItemListener() { @Override public void itemStateChanged(final ItemEvent e) { /* JOptionPane.showMessageDialog( (Component) e.getSource(), e.getSource().toString(), "Item Listener fired", JOptionPane.INFORMATION_MESSAGE); */ /* JOptionPane.showMessageDialog( (Component) e.getSource(), "hi"); */ // JOptionPane.showMessageDialog(null, "hi"); // When a JOptionPane runs in the same thread as // the JFrame, strange behavior can occur as seen // in the commented code above (the ItemListener // will fire TWICE, and deselect the JCheckBox that // you have selected. javax.swing.SwingUtilities.invokeLater(new Runnable() { @Override public void run() { // ItemEvent e must be final in the enclosing scope. JOptionPane.showMessageDialog( (Component) e.getSource(), e.getSource(), "Item Listener fired", JOptionPane.INFORMATION_MESSAGE); } }); /* JOptionPane.showMessageDialog(null, e.getStateChange(), "Deselected = 2; Selected = 1", JOptionPane.INFORMATION_MESSAGE); */ System.out.println("hello"); } }; MouseListener myDoubleClickMouseListener = new MouseAdapter() { @Override public void mouseClicked(MouseEvent e) { // Mouse Events have more information. if (e.getClickCount() == 2) JOptionPane.showMessageDialog(null, "You clicked twice?"); } }; MouseListener myClickMouseListener = new MouseAdapter() { @Override public void mousePressed(MouseEvent e) { // Mouse Events have more information. JOptionPane.showMessageDialog(null, "You pressed " + MouseEvent.getMouseModifiersText(e.getModifiersEx())); } }; /* ****************** end inner class *********************/ loginButton.addActionListener(myButtonListener); registerButton.addActionListener(myButtonListener); rightClickButton.addMouseListener(myClickMouseListener); doubleClickButton.addMouseListener(myDoubleClickMouseListener); // chkMember.addActionListener(myCheckboxActionListener); chkMember.addItemListener(myCheckboxItemListener); /* This also creates an anonymous inner class * * What are the advantages of independent listeners like * this one, versus a consolidated listener? */ ActionListener helpActionListener = new ActionListener() { @Override public void actionPerformed(ActionEvent e) { // This label was static so every method could access it. messageLabel.setText("Help is on the way."); messageLabel.setForeground(Color.RED); } }; helpButton.addActionListener(helpActionListener); } }