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How to use the ActionListener interface

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• The ActionListener Interface
  • Events handled by the ActionListener interface:

    Mouse click Pressing "Enter" key

  • The definition of the ActionListener interface:

    interface ActionListener { void actionPerformed(ActionEvent e); // Called when Mouse click OR // when ENTER key pressed }

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• Example using the ActionListener Interface:    make a button respond to mouse click
  • First: make a JFrame with a JButton - we have seen this already !

    import javax.swing.*; import java.awt.*; import java.awt.event.*; public class ButtonPressAppl { public static void main(String[] args) { JFrame f = new JFrame("Button Test"); JButton B; B = new JButton("Press me !"); f.getContentPane().add(B); // Add button f.setSize(300, 300); f.setVisible(true); } }

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  • Next: define the call-back functions in the desired interface for the JButton

    public static class myListener implements ActionListener { public void actionPerformed(ActionEvent event) { System.out.println("The button was press !"); } }

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  • Finally: register the call-back function for the JFrame and for the JButton

    import javax.swing.*; import java.awt.*; import java.awt.event.*; public class ButtonPressAppl { public static void main(String[] args) { JFrame f = new JFrame("Button Test"); JButton B; B = new JButton("Press me !"); f.getContentPane().add(B); // Add button B.addActionListener(new myListener() ); // Register ActionListen Interface class f.setSize(300, 300); f.setVisible(true); } public static class myListener implements ActionListener { public void actionPerformed(ActionEvent event) { System.out.println("The button was press !"); } } }

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  • Example Program: (Demo above code)                        
    • Prog file: /home/cs377001/demo/GUI/ButtonPressAppl.java