Help: Inspecting Beans with BeanInfo and Juan Valdez

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Help: Inspecting Beans with BeanInfo and Juan Valdez
MageLang Institute

Help is available for each task, or you can go straight to the solution source code.

Task 1

The Introspector is used to get the BeanInfo of a Bean. Since it works with an instance of Class, you need to get the Class of the bean passed to our inspect method.

Use the Object.getClass method.

Task 2

Now that you have a Class, use the Introspector to get at its BeanInfo.

Use the Introspector.getBeanInfo method and remember to catch the IntrospectionException exception.

Task 3

From the BeanInfo, get the list of properties for the Bean. You will end up with an array of PropertyDescriptors.

Use the BeanInfo.getPropertyDescriptors method.

Task 4

For each element of the PropertyDescriptor array, display the name, datatype, and current value.

PropertyDescriptor is a subclass of FeatureDescriptor. Use the FeatureDescriptor.getName method to find out each name.
PropertyDescriptor has a getPropertyType method to get the Class for each property.
PropertyDescriptor also has a getReadMethod method to get the read Method for the property. Use the Method.invokeMethod routine to invoke it. Since the read methods take no parameters, you can pass it null for the Object[] it is expecting for parameters.
- If the property is read-only, getReadMethod returns null.
- The Method.invoke method can throw three exceptions, IllegalArgumentException, IllegalAccessException, or InvocationTargetException.

Task 5

From the BeanInfo, get the list of event sets for the Bean. You will end up with an array of EventSetDescriptors.

Use the BeanInfo.getEventSetDescriptors method.

Task 6

For each element of the EventSetDescriptor array, display the name and listener type.

EventSetDescriptor is a subclass of FeatureDescriptor. Use the FeatureDescriptor.getName method to find out each name.
EventSetDescriptor has a getListenerType method to get the Class whose interface will be invoked when the event is fired.

Task 7

Use the Burro frame provided in Burro.java to test out the inspect method of Valdez. Burro creates a Frame with a bunch of AWT Beans on it. When you double-click on a List element, select a Checkbox, or press return in the TextField, Juan goes to work and inspects the Bean selected. The results of the inspection are shown in the TextArea in the middle.

Compile and run: javac Burro.java java Burro