Wrapper classes in java with easy explanation.
Wrapper class is a mechanism which provides the facility to convert primitive data type into the object and object into primitive data type.
Java 5 provides the two features:
1.Autoboxing
2. Unboxing
1.Autoboxing
Automatic conversion of primitive data type into an object then this process is known as autoboxing.
2.Unboxing
Automatic conversion of an object into primitive data type then this process is known as Unboxing.
Why need wrapper class in java
1.It converts primitive data type into an object and vice-versa.
2.All the Collection Frameworks classes such as ArrayList,LinkedList,HashSet etc only works with objects.
3. The java.util.package provides the facility to work with objects.
4.Primitive can not be null but wrapper class may be null.
5.It can be used to achieve polymorphism.
Primitive data types equivalent with the wrapper class
Primitive data type | Wrapper class |
boolean | Boolean |
byte | Byte |
short | Short |
int | Integer |
float | Float |
double | Double |
long | Long |
char | Character |
Example of Autoboxing
Autoboxing is an automatic process which converts the primitive data type into equivalent wrapper class.
In java 5,We do not required to use valueOf( ) method to convert primitive data type into objects.
Example:
Int to Integer,byte to Byte etc
public class AutoboxingWrapperClass { public static void main(String[ ] args) { int a=10; Integer i=Integer.valueOf(a); //converting int into Integer Integer k=a; //Automatic converting int into Integer System.out.println(k); } }
Output:
10
Example of Unboxing
Unboxing is an automatic process which converts the wrapper class into equivalent primitive data type.
Example:
Integer to int,Byte to byte etc
public class UnboxingWrapperClass { public static void main(String[ ] args) { Integer i=new Integer(10); int k=i; //Automatic converting Integer into int System.out.println(k); } }
Output:
10
Example of wrapper class:
Here we will try to understand the example of both autoboxing and unboxing of the wrapper class.
public class WrapperClass { public static void main(String[ ] args) { //integer data type int x=10; //converting int to Integer(primitive into object) Integer i_obj=new Integer(x); //byte data type byte b=20; //converting byte into Byte Byte b_obj=new Byte(b); //Printing the value of primitive data type into object System.out.println(“Wrapper to objects values are given:”); System.out.print(“Integer primitive to object=”+i_obj); System.out.print(“Byte primitive to object=”+b_obj); //Now wrapping an objects into the primitive data type int i_primitive=i_obj; byte b_primitive=b_obj; //Printing the primitive data types value System.out.println(“objects to wrapper values are given:”); System.out.print(“Integer obj to primitive =”+i_primitive); System.out.print(“Byte obj to primitive=”+b_primitive); } }
Output:
Wrapper to objects values are given:
Integer primitive to object=10
Byte primitive to object=20
objects to wrapper values are given:
Integer obj to primitive=10
Byte obj to primitive=20
Hope,I explained all the things about the wrapper class in java step by step with easy explanation.If you still have any query comment me.
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