Summary of Variables - Java Tutorial 5.0 英文版

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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 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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