Q 22 - Variable Scope

[HARSHITH-MV]

What is the scope of variables ? 🤓

[AmjustGettingStarted]

🔍 Types of Scope in Java

1. Class Scope

• Applies to variables declared inside a class but outside any method.
• These are typically instance variables or static variables.
• Accessible throughout the class.
• Example:

  class Car {
      int speed;         // instance variable
      static int wheels; // static variable
  }

2. Method Scope

• Variables declared inside a method.
• Accessible only within that method.
• Destroyed once the method finishes execution.
• Example:

  void drive() {
      int distance = 100; // method scope
  }

3. Block Scope

• Applies to variables declared inside loops, conditionals, or any {} block.
• Accessible only within that block.
• Example:

  if (true) {
      int x = 5; // block scope
  }
  // x is not accessible here

4. Loop Scope

• A special case of block scope.
• Variables declared in for, while, or do-while loops are scoped to the loop.
• Example:

  for (int i = 0; i < 5; i++) {
      System.out.println(i); // i is loop-scoped
  }

5. Parameter Scope

• Applies to method parameters.
• Accessible only within the method they’re declared in.
• Example:

  void greet(String name) {
      System.out.println("Hello " + name); // name is parameter-scoped
  }

🧠 Quick Tip

In Java, curly braces {} define scope boundaries. If a variable is declared inside a set of braces, it lives and dies there.

[AmjustGettingStarted]

😎 In Java, variable scope refers to the part of the program where a variable is accessible. It determines the lifespan and visibility of that variable. Here's a breakdown:

🔍 Types of Variable Scope in Java

1. Local Variables

• Declared inside a method, constructor, or block.
• Accessible only within that method/block.
• Automatically destroyed once the method finishes.
• Example:

  void greet() {
      String message = "Hello!";
      System.out.println(message); // message is accessible here
  }

2. Instance Variables

• Declared inside a class but outside any method.
• Belong to each object of the class.
• Accessible by all methods of the class using this reference.
• Example:

  class Person {
      String name; // instance variable
  
      void printName() {
          System.out.println(name);
      }
  }

3. Class Variables (Static Variables)

• Declared with the static keyword inside a class.
• Shared among all instances of the class.
• Can be accessed using the class name.
• Example:

  class Counter {
      static int count = 0;
  
      Counter() {
          count++;
      }
  }

🧠 Bonus Tip

If a variable is declared inside a loop or an if block, it's scoped just to that block. So be mindful of curly braces {} when you're trying to reuse a variable!