Introducing Classes, Objects, and Methods - Java: A Beginner's Guide - page 171

Here, the keyword protected is a specifier that limits access to finalize( ) . This and the
other access specifiers are explained in Chapter 6 .
It is important to understand that finalize( ) is called just before 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. For example, if your program ends
before garbage collection occurs, finalize( ) will not execute. Therefore, it should be used
as a “backup” procedure to ensure the proper handling of some resource, or for special-use
applications, not as the means that your program uses in its normal operation. In short, fi-
nalize( ) is a specialized method that is seldom needed by most programs.

Ask the Expert

Q :

I know that C++ defines things called destructors , which are automatically ex-
ecuted when an object is destroyed. Is finalize( ) similar to a destructor?

A : Java does not have destructors. Although it is true that the finalize( ) method approx-
imates the function of a destructor, it is not the same. For example, a C++ destructor
is always called just before an object goes out of scope, but you can't know when fi-
nalize( ) will be called for any specific object. Frankly, because of Java's use of
garbage collection, there is little need for a destructor.

Try This 4-2 Demonstrate Garbage Collection and Finalization