Autoboxing And Unboxing In Java

| next>><<prevAutoboxing and Unboxing in JavaLast Updated : 17 Mar 2025The automatic conversion of primitive data types into its equivalent Wrapper type is known as boxing and opposite operation is known as unboxing. This is the new feature of Java5. So java programmer doesn't need to write the conversion code.Advantage of Autoboxing and Unboxing:No need of conversion between primitives and Wrappers manually so less coding is required.Simple Example of Autoboxing in Javaclass BoxingExample1{

public static void main(String args){

int a=50;

Integer a2=new Integer(a);//Boxing

Integer a3=5;//Boxing

System.out.println(a2+" "+a3);

}

}Test it NowOutput:50 5Simple Example of Unboxing in java:The automatic conversion of wrapper class type into corresponding primitive type, is known as Unboxing. Let's see the example of unboxing:class UnboxingExample1{

public static void main(String args){

Integer i=new Integer(50);

int a=i;

System.out.println(a);

}

}Test it NowOutput:50Autoboxing and Unboxing with comparison operatorsAutoboxing can be performed with comparison operators. Let's see the example of boxing with comparison operator:class UnboxingExample2{

public static void main(String args){

Integer i=new Integer(50);

if(i<100){ //unboxing internally

System.out.println(i);

}

}

}Test it NowOutput:50Autoboxing and Unboxing with method overloadingIn method overloading, boxing and unboxing can be performed. There are some rules for method overloading with boxing:Widening beats boxingWidening beats varargsBoxing beats varargs1) Example of Autoboxing where widening beats boxingIf there is possibility of widening and boxing, widening beats boxing.class Boxing1{

static void m(int i){System.out.println("int");}

static void m(Integer i){System.out.println("Integer");}

public static void main(String args){

short s=30;

m(s);

}

}Test it NowOutput:int2) Example of Autoboxing where widening beats varargsIf there is possibility of widening and varargs, widening beats var-args.class Boxing2{

static void m(int i, int i2){System.out.println("int int");}

static void m(Integer... i){System.out.println("Integer...");}

public static void main(String args){

short s1=30,s2=40;

m(s1,s2);

}

}Test it NowOutput:int int3) Example of Autoboxing where boxing beats varargsLet's see the program where boxing beats variable argument:class Boxing3{

static void m(Integer i){System.out.println("Integer");}

static void m(Integer... i){System.out.println("Integer...");}

public static void main(String args){

int a=30;

m(a);

}

}Test it NowOutput:IntegerMethod overloading with Widening and BoxingWidening and Boxing can't be performed as given below:class Boxing4{

static void m(Long l){System.out.println("Long");}

public static void main(String args){

int a=30;

m(a);

}

}Test it NowOutput:Compile Time ErrorNext TopicJava Varargs<<prevnext>> | Autoboxing can be performed with comparison operators. Let's see the example of boxing with comparison operator: | In method overloading, boxing and unboxing can be performed. There are some rules for method overloading with boxing:Widening beats boxingWidening beats varargsBoxing beats varargs | If there is possibility of widening and boxing, widening beats boxing. | If there is possibility of widening and varargs, widening beats var-args. | Let's see the program where boxing beats variable argument: | Widening and Boxing can't be performed as given below: |

The process of automatically converting primitive data types to their corresponding Wrapper types is referred to as boxing, with the reverse process being known as unboxing. This functionality was introduced in Java5, eliminating the need for Java programmers to manually code these conversions.

Advantage of Autoboxing and Unboxing:

Manual conversion between primitive data types and their corresponding wrapper classes is unnecessary, reducing the amount of code that needs to be written.

Simple Example of Autoboxing in Java

class BoxingExample1{

  public static void main(String args[]){

	int a=50;

        Integer a2=new Integer(a);//Boxing



        Integer a3=5;//Boxing

        

        System.out.println(a2+" "+a3);

 } 

}

Output:50 5

Simple Example of Unboxing in java:

Unboxing refers to the automated conversion of a wrapper class type into its corresponding primitive type. Let's illustrate unboxing with an example:

class UnboxingExample1{

  public static void main(String args[]){

	Integer i=new Integer(50);

        int a=i;

        

        System.out.println(a);

 } 

}

Output:

Autoboxing and Unboxing with comparison operators

class UnboxingExample2{

  public static void main(String args[]){

	Integer i=new Integer(50);

        

        if(i<100){            //unboxing internally

        System.out.println(i);

        }

 } 

}

Output:50

Autoboxing and Unboxing with method overloading

• ✅ Widening beats boxing
• ✅ Widening beats varargs
• ✅ Boxing beats varargs

1) Example of Autoboxing where widening beats boxing

class Boxing1{

  static void m(int i){System.out.println("int");}

  static void m(Integer i){System.out.println("Integer");}



  public static void main(String args[]){

   short s=30;

   m(s);

 } 

}

Output:int

2) Example of Autoboxing where widening beats varargs

class Boxing2{

  static void m(int i, int i2){System.out.println("int int");}

  static void m(Integer... i){System.out.println("Integer...");}



  public static void main(String args[]){

   short s1=30,s2=40;

   m(s1,s2);

 } 

}

Output:int int

3) Example of Autoboxing where boxing beats varargs

class Boxing3{

  static void m(Integer i){System.out.println("Integer");}

  static void m(Integer... i){System.out.println("Integer...");}



  public static void main(String args[]){

   int a=30;

   m(a);

 } 

}

Output:Integer

Method overloading with Widening and Boxing

class Boxing4{

  static void m(Long l){System.out.println("Long");}



  public static void main(String args[]){

   int a=30;

   m(a);

 } 

}

Output:Compile Time Error