UniversalActionListenerpublic class UniversalActionListener extends Object implements ActionListener
| Fields Summary |
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| protected Object | target | | protected Object | arg | | protected Method | m |
| Constructors Summary |
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public UniversalActionListener(Object target, String methodname, Object arg)
this.target = target; // Save the target object.
this.arg = arg; // And method argument.
// Now look up and save the Method to invoke on that target object
Class c, parameters[];
c = target.getClass(); // The Class object.
if (arg == null) parameters = new Class[0]; // Method parameter.
else parameters = new Class[] { arg.getClass() };
m = c.getMethod(methodname, parameters); // Find matching method.
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| Methods Summary |
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| public void | actionPerformed(java.awt.event.ActionEvent event)
Object[] arguments;
if (arg == null) arguments = new Object[0]; // Set up arguments.
else arguments = new Object[] { arg };
try { m.invoke(target, arguments); } // And invoke the method.
catch (IllegalAccessException e) { // Should never happen.
System.err.println("UniversalActionListener: " + e);
} catch (InvocationTargetException e) { // Should never happen.
System.err.println("UniversalActionListener: " + e);
}
| | public static void | main(java.lang.String[] args)
Frame f = new Frame("UniversalActionListener Test");// Create window.
f.setLayout(new FlowLayout()); // Set layout manager.
Button b1 = new Button("tick"); // Create buttons.
Button b2 = new Button("tock");
Button b3 = new Button("Close Window");
f.add(b1); f.add(b2); f.add(b3); // Add them to window.
// Specify what the buttons do. Invoke a named method with
// the UniversalActionListener object.
b1.addActionListener(new UniversalActionListener(b1, "setLabel", "tock"));
b1.addActionListener(new UniversalActionListener(b2, "setLabel", "tick"));
b1.addActionListener(new UniversalActionListener(b3, "hide", null));
b2.addActionListener(new UniversalActionListener(b1, "setLabel", "tick"));
b2.addActionListener(new UniversalActionListener(b2, "setLabel", "tock"));
b2.addActionListener(new UniversalActionListener(b3, "show", null));
b3.addActionListener(new UniversalActionListener(f, "dispose", null));
f.pack(); // Set window size.
f.show(); // And pop it up.
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