Wrapper Class:

In Java there are 8 primitive data types and to convert them into object we use wrapper classes. We use boxing and autoboxing to convert primitive into object and object into primitive.

Primitive type and their correspnding wrapper classes:

 Converting Primitive to Wrapper:

    public class PrimitivetoWrapper{  
    public static void main(String args[]){  
      
    int m=10;  
    Integer i=Integer.valueOf(m);//converting int into Integer  
    Integer j=m;//autoboxing, compiler will write Integer.valueOf(m) internally  
      
    System.out.println(m+" "+i+" "+j);  
    }}  

In the above example we are wrapping int m into its wrapper class(Integer) and showing its value.

Converting Wrapper to Primitive:

    public class WrappertoPrimitive{    
    public static void main(String args[]){    
     
    Integer m=new Integer(3);    
    int i=m.intValue();//converting Integer to int  
    int j=m;//unboxing, now compiler will write m.intValue() internally    
        
    System.out.println(m+" "+i+" "+j);    
    }}    

In the above example we are unwrapping "m"(Integer)  into its primitive type(int) and showing its value.