Autoboxing

Autoboxing is a feature introduced in Java 5 and can be defined as converting primitive data type into it's equivalent wrapper type automatically. In Java,for every primitive type there is a corresponding class of reference type and these classes are called wrapper class. For e.g: int primitive type is converted to Integer wrapper type in autoboxing. Autoboxing is used whenever a primitive type is to be treated as an object i.e instead of object a primitive type is available then it is converted to object. For e.g: ArrayList class requires an object reference.

ArrayList<Integer> intList = new ArrayList<Integer>();
intList.add(1); //autoboxing - primitive to object
intList.add(2); //autoboxing

Program to demonstrate Autoboxing:

class AutoBoxingExample
{  
  public static void main(String args[])
   {  
    int a=50;
    //passing a primitive type(int) to wrapper type(Integer),automatic conversion autoboxing 
    Integer a2=new Integer(a);  
  
        Integer a3=5;//autoboxing  
          
        System.out.println(a2+" "+a3);  
 }   
}  

Output: 

50 5

Unboxing

Unboxing is a feature introduced in Java 5 and can be defined as converting wrapper type into it's equivalent primitive type automatically.

Program to demonstrate Unboxing:

class UnboxingExample
{  
  public static void main(String args[])
  {  
    Integer i=new Integer(50);  //Integer wrapper class is used

        int a=i;    // Unboxing
          
        System.out.println(a);  
 }   
}  

Output:

50