What is type casting in Java?

Type casting in Java is the process of converting a value of one data type to another data type.

Types of casting:

• Explicit Casting: Performed by the programmer using the (type) operator. Used to convert from a "larger" type to a "smaller" type (e.g., double to int). It may lead to data loss.

  // implicit casting (automatic)
  int a = 10;
  double b = a; // int to double
  
  // explicit casting (manual)
  double c = 10.5;
  int d = (int) c; // double to int, d will be 10
  

• Implicit Casting / Widening Conversion: Performed automatically by the JVM when converting from a "smaller" type to a "larger" type (e.g., int to double). It is safe and does not lead to data loss.

  int x = 10;
  double y = x; // int automatically cast to double
  

Casting can be between primitive types or between object types in an inheritance hierarchy.

When casting object types:

• Upcasting: Casting a subclass to its superclass. It is implicit and safe.

  class Animal {}
  class Dog extends Animal {}
  
  Animal animal = new Dog(); // Upcasting
  

• Downcasting: Casting a superclass to its subclass. It requires explicit casting and may throw a ClassCastException at runtime if the object is not actually an instance of the target subclass.

  Animal animal = new Dog(); // Upcasting
  
  // Downcasting - requires explicit casting and instanceof check
  if (animal instanceof Dog) {
      Dog dog = (Dog) animal;
      // Now you can use methods specific to Dog
  }