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Trail: Learning the Java Language
Lesson: Language Basics

Summary of Variables

When you declare a variable, you explicitly set the variable's name and data type. The Java programming language has two categories of data types: primitive and reference. A variable of primitive type contains a value. The first table in the Data Types (in the Learning the Java Language trail) section shows all of the primitive data types along with their sizes and formats. Keep in mind that a variable of reference type contains a reference to a value. Arrays, classes, and interfaces are reference types.

The location of a variable declaration implicitly sets the variable's scope, which determines which section of code may refer to the variable by its simple name. There are four categories of scope: member variable scope, local variable scope, parameter scope, and exception-handler parameter scope.

You can provide an initial value for a variable within its declaration by using the assignment operator (=). You can declare a variable as final. The value of a final variable cannot change after it has been initialized.


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