Local, Global & Static Variables in Java 🚀
By Bhau Automation • Java Variables Tutorial for Beginners
🎯 What You Will Learn
- What are variables in Java?
- Difference between local, global and static variables
- Variable declaration and initialization
- Memory allocation of variables
- Java variable examples
- Java interview questions on variables
💡 Variables are one of the most important concepts in Java programming and are used in every Java application.
📌 What is a Variable in Java?
A variable in Java is a container used to store data values during program execution.
Variables help programs:
- Store information temporarily
- Perform calculations
- Manage application data
- Control program flow
🛠️ Variable Declaration in Java
Syntax of variable declaration:
dataType variableName = value;
Example:
int age = 25;
📍 What is Local Variable?
A local variable is declared inside a method, constructor, or block and can only be accessed within that scope.
💻 Local Variable Example
public class LocalVariableDemo {
public void display() {
int number = 10;
System.out.println(number);
}
}
🌍 What is Global Variable?
A global variable (instance variable) is declared inside class but outside methods. It is accessible throughout the class using objects.
💻 Global Variable Example
public class GlobalVariableDemo {
int salary = 50000;
public void show() {
System.out.println(salary);
}
}
⚡ What is Static Variable?
A static variable belongs to the class instead of object. Only one copy of static variable is shared among all objects.
💻 Static Variable Example
public class StaticVariableDemo {
static String company = "Bhau Automation";
public static void main(String[] args) {
System.out.println(company);
}
}
📊 Difference Between Local, Global & Static Variables
| Feature | Local Variable | Global Variable | Static Variable |
|---|---|---|---|
| Declaration | Inside method | Inside class | Using static keyword |
| Scope | Within method only | Entire class | Shared across objects |
| Memory Allocation | Stack Memory | Heap Memory | Method Area |
🧠 Variable Initialization
Variable initialization means assigning value to variable before using it.
int marks = 90;
💾 Memory Allocation of Variables
- Local variables → Stack memory
- Instance variables → Heap memory
- Static variables → Method area memory
🌍 Real-World Use Cases
- Student management systems
- Banking applications
- Selenium automation frameworks
- Enterprise Java applications
- Cyber security tools
❓ Common Interview Questions
Q: What is the difference between local and global variable?
A: Local variables are declared inside methods, while global variables are declared inside class outside methods.
Q: Why do we use static variables?
A: Static variables are shared across all objects and save memory.
Q: Where are local variables stored?
A: Local variables are stored in stack memory.
🎥 Watch Complete Video Tutorial
👉 Watch Java Variables Tutorial
🎓 Key Takeaways
- Variables store data values in Java
- Local variables work inside methods only
- Global variables belong to objects
- Static variables are shared across objects
- Important Java interview topic for beginners
⚡ Pro Tip: Practice variable declaration and initialization programs regularly to strengthen Java programming fundamentals.
🚀 Created with ❤️ by Bhau Automation