GUI Components: Part 1 - Java: How to Program Early Objects - page 519

Event-adapter class in java.awt.event Implements interface

ComponentAdapter ComponentListener

ContainerAdapter ContainerListener

FocusAdapter FocusListener

KeyAdapter KeyListener

MouseAdapter MouseListener

MouseMotionAdapter MouseMotionListener

WindowAdapter WindowListener

Fig. 12.30 | Event-adapter classes and the interfaces they implement.

Extending MouseAdapter
The application of Figs. 12.31-12.32 demonstrates how to determine the number of
mouse clicks (i.e., the click count) and how to distinguish between the different mouse
buttons. The event listener in this application is an object of inner class MouseClickHan-
dler (Fig. 12.31, lines 25-46) that extends MouseAdapter , so we can declare just the
mouseClicked method we need in this example.

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// Fig. 12.31: MouseDetailsFrame.java

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// Demonstrating mouse clicks and distinguishing between mouse buttons.

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import java.awt.BorderLayout;

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import java.awt.event.MouseAdapter;

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import java.awt.event.MouseEvent;

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import javax.swing.JFrame;

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import javax.swing.JLabel;

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public class MouseDetailsFrame extends JFrame

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{

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private String details; // String displayed in the statusBar

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private final JLabel statusBar; // JLabel at bottom of window

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// constructor sets title bar String and register mouse listener

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public MouseDetailsFrame()

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{

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super ( "Mouse clicks and buttons" );

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statusBar = new JLabel( "Click the mouse" );

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add(statusBar, BorderLayout.SOUTH );

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addMouseListener( new MouseClickHandler()); // add handler

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}

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// inner class to handle mouse events

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private class MouseClickHandler extends MouseAdapter

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{

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// handle mouse-click event and determine which button was pressed

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@Override

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public void mouseClicked(MouseEvent event)

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{

Fig. 12.31 | Demonstrating mouse clicks and distinguishing between mouse buttons. (Part 1 of 2.)