Scope

Scope of a variable is its lifetime in the program.

The region of the program in which it can be accessed.

Local Scope

A scope can also be viewed as the space between two curly brackets - { }.

Example:

import java.util.*; class HelloWorld { public static void main(String[] args) { int num1 = 5; if (true) { int num2 = 6; System.out.println(num1); System.out.println(num2); } System.out.println(num1); // System.out.println(num2); } }

Output:

5 6 5

In this example the num1 variable can be accessed anywhere in the main function.

The num2 variable is defined inside the if statement and can be accessed only inside it - between it's curly brackets - { }.

If we uncomment line 15, it will result in exception because num2 is accessed outside of it's scope - between line 8 and line 12.

Scopes are not limited only to if statements. It's also valid for loops too.

Let's look at the following example:

import java.util.*; class HelloWorld { public static void main(String[] args) { for (int i = 0; i < 3; i++) { System.out.println(i); int num = 4; System.out.println(num); } // System.out.println(num1); // System.out.println(i); } }

Output:

0 4 1 4 2 4

In this case both variables i and num can be accessed inside their scope - the for loop.

But if we uncomment line 13 or line 14, an exception will be thrown.