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Java programming language. Lessons for beginners

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Java Constants (final)


Constants (final keyword)

When you do not want a variable's value to change, use the final keyword.

A variable declared with final becomes a constant, which means unchangeable and read-only:

Example

final int myNum = 15;
myNum = 20;  // Error: cannot assign a value to final variable 'myNum'

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When to Use final?

You should declare variables as final when their values should never change. For example, the number of minutes in an hour, or your birth year:

Example

final int MINUTES_PER_HOUR = 60;
final int BIRTHYEAR = 1980;

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Note: By convention, final variables in Java are usually written in upper case (e.g. BIRTHYEAR). It is not required, but useful for code readability and common for many programmers.