What is the default value of a local variable?

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In Java, there are three main types of variables:

1. Local Variables

  • Definition: Declared within a method, constructor, or block.
  • Scope: Only accessible within the method or block where it is declared.
  • Lifetime: Created when the method is called and destroyed when the method exits.
  • Default Value: No default value, must be explicitly initialized.
  • Example:

java public void method() { int localVar = 10; // Local variable }

2. Instance Variables (Non-static Fields)

  • Definition: Declared inside a class but outside any method or constructor. They are also called non-static fields.
  • Scope: Each object has its own copy of instance variables.
  • Lifetime: Created when an object is instantiated and destroyed when the object is destroyed.
  • Default Value: Automatically initialized to default values (e.g., 0 for numeric types, null for object references).
  • Example:

java class MyClass { int instanceVar = 5; // Instance variable }

3. Static Variables (Class Variables)

  • Definition: Declared with the static keyword within a class, but outside any method or constructor. These are shared among all instances of the class.
  • Scope: Belong to the class, and only one copy exists, regardless of how many objects are created.
  • Lifetime: Created when the class is loaded and destroyed when the class is unloaded.
  • Default Value: Automatically initialized to default values like instance variables.
  • Example:

java class MyClass { static int staticVar = 10; // Static variable }