finalize in Java

Sometimes an object will need to perform some action when it is destroyed. For example,
if an object is holding some non-Java resource such as a file handle or character font, then
you might want to make sure these resources are freed before an object is destroyed. To
handle such situations, Java provides a mechanism called finalization. By using finalization,
you can define specific actions that will occur when an object is just about to be reclaimed
by the garbage collector.

To add a finalizer to a class, you simply define the finalize( ) method. The Java run time
calls that method whenever it is about to recycle an object of that class. Inside the finalize( )
method, you will specify those actions that must be performed before an object is destroyed.
The garbage collector runs periodically, checking for objects that are no longer referenced
by any running state or indirectly through other referenced objects. Right before an asset is
freed, the Java run time calls the finalize( ) method on the object.

The finalize( ) method has this general form:

protected void finalize( )
{
// finalization code here
}

Here, the keyword protected is a specifier that limits access to finalize( ).

It is important to understand that finalize( ) is only called just prior to garbage collection.
It is not called when an object goes out-of-scope, for example. This means that you cannot
know when—or even if—finalize( ) will be executed. Therefore, your program should
provide other means of releasing system resources, etc., used by the object. It must not
rely on finalize( ) for normal program operation.

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