Java, A Beginner's Guide, 5th Edition, 5th Edition

The Scope and Lifetime of Variables

So far, all of the variables that we have been using were declared at the start of the main( ) method. However, Java allows variables to be declared within any block. As explained in Chapter 1, a block is begun with an opening curly brace and ended by a closing curly brace. A block defines a scope. Thus, each time you start a new block, you are creating a new scope. A scope determines what objects are visible to other parts of your program. It also determines the lifetime of those objects.

Many other computer languages define two general categories of scopes: global and local. Although supported by Java, these are not the best ways to categorize Java’s scopes. The most important scopes in Java are those defined ...