Wrapper class in java

Java provides classes that correspond to each of the simple types. In essence, these classes

encapsulate, or wrap, the simple types within a class. Thus, they are commonly referred to as

wrapper classes.

Wrapper class in java provides the mechanism to convert primitive into object and object into

primitive. Autoboxing and unboxing feature facilitates the process of generates a code implicitly

to convert primitive type to the corresponding wrapper class type and vice-versa.

One of the eight classes of java.lang package are known as wrapper class in java.

The list of eight wrapper classes are given below:

Wrapper class in java

Wrapper class Example: Primitive to Wrapper

public class WrapperExample1{

public static void main(String args[]){

//Converting int into Integer

int a=20;

Integer i=Integer.valueOf(a); //converting int into Integer

Integer j=a; //autoboxing, now compiler will write Integer.valueOf(a) internally

System.out.println(a+" "+i+" "+j);

}}

Output:

20 20 20

Wrapper class Example: Wrapper to Primitive

public class WrapperExample2{

public static void main(String args[]){

//Converting Integer to int

Integer a=new Integer(3);

int i=a.intValue(); //converting Integer to int

int j=a; //unboxing, now compiler will write a.intValue() internally

System.out.println(a+" "+i+" "+j);

}}

Output:

3 3 3