Global Variable VS Local Variable

In Java, variables are classified based on where they are declared and how they are accessed. The two main types are global (class-level) variables and local variables. Understanding their scope and behavior is essential for writing efficient programs.

What is a Global Variable in Java?

Java does not support true global variables like some other languages. Instead, it uses class-level variables, which behave similarly.
These variables are declared inside a class but outside any method.

Types of Class-Level Variables
Static Variable → Shared by all objects
Instance Variable → Separate copy for each object

Example:

class Test {
    static int x = 10;   // class-level (global-like)

    public static void main(String[] args) {
        System.out.println(x);
    }
}

OutPut

What is a Local Variable?
A local variable is declared inside a method, constructor, or block and can only be used within that scope.

Example:

class Test 
{ 
public static void main(String[] args) 
{ 
int y = 5; // local variable 
System.out.println(y); 
} 
}

Output

Key Characteristics

• Declared inside method / block
• Accessible only within that method
• Memory created when method starts
• Destroyed when method ends
• Must be initialized before use