Difference Between Local, Global and Static Variables in Java

By Bhau Automation • Understand Java Variable Types Practically

🎯 What You Will Learn in This Video

• What are variables in Java?
• Types of variables: local, global (instance), and static
• Memory allocation and lifetime of variables
• Difference between local, instance, and static variables
• Real-time examples of each variable type
• Practical demonstration in Eclipse IDE

💡 Pro Tip: Understanding how Java variables work is key to mastering memory management and writing efficient code.

📘 What is a Variable in Java?

In Java, a variable is a container that holds data during program execution. Every variable has a data type, name, and scope. Based on where it is declared, it can be categorized into three types.

🔹 Types of Variables in Java

• Local Variables: Declared inside methods, constructors, or blocks. They are created when the method is invoked and destroyed when it ends.
• Instance (Global) Variables: Declared inside a class but outside any method. Each object has its own copy.
• Static Variables: Declared using the static keyword. Shared among all objects of a class.

💻 Java Example Demonstrating All Three

class VariableDemo {
    int instanceVar = 100; // Instance (global) variable
    static int staticVar = 200; // Static variable

    void display() {
        int localVar = 50; // Local variable
        System.out.println("Local Variable: " + localVar);
        System.out.println("Instance Variable: " + instanceVar);
        System.out.println("Static Variable: " + staticVar);
    }

    public static void main(String[] args) {
        VariableDemo obj1 = new VariableDemo();
        obj1.display();

        VariableDemo obj2 = new VariableDemo();
        obj2.instanceVar = 300;
        VariableDemo.staticVar = 400;

        obj2.display();
    }
}
  

📊 Key Differences

🎥 Watch the Complete Video Tutorial

👉 Watch on YouTube: Local, Global, and Static Variables in Java

🧠 Key Takeaways

• Local variables exist only inside methods and must be initialized manually.
• Instance variables belong to objects — each object has its own copy.
• Static variables are shared among all objects and belong to the class.
• Understanding variable scope helps manage memory efficiently.

⚡ Next Steps: Practice declaring all three variable types in your own Java class and observe their behavior during runtime.

🚀 Created with ❤️ by Bhau Automation