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Question 36 :

Under what conditions is an object's finalize() method invoked by the garbage collector?

Answer :

The garbage collector invokes an object's finalize() method when it detects that the object has become unreachable.


Question 37 :

How are this () and super () used with constructors?

Answer :

this() is used to invoke a constructor of the same class. super() is used to invoke a superclass constructor.


Question 38 :

What is the relationship between a method's throws clause and the exceptions that can be thrown during the method's execution?

Answer :

A method's throws clause must declare any checked exceptions that are not caught within the body of the method.


Question 39 :

What is the difference between the JDK 1.02 event model and the event-delegation model introduced with JDK 1.1?

Answer :

The JDK 1.02 event model uses an event inheritance or bubbling approach. In this model, components are required to handle their own events. If they do not handle a particular event, the event is inherited by (or bubbled up to) the component's container. The container then either handles the event or it is bubbled up to its container and so on, until the highest-level container has been tried. In the event-delegation model, specific objects are designated as event handlers for GUI components. These objects implement event-listener interfaces. The event-delegation model is more efficient than the event-inheritance model because it eliminates the processing required to support the bubbling of unhandled events.


Question 40 :

How is it possible for two String objects with identical values not to be equal under the == operator?

Answer :

The == operator compares two objects to determine if they are the same object in memory. It is possible for two String objects to have the same value, but located indifferent areas of memory.