Wrapper class in Java

According to Wikipedia “In object-oriented programming, a wrapper class is a class that encapsulates types, so that those types can be used to create object instances and methods in another class that needs those types. So a primitive wrapper class is a wrapper class that encapsulates hides or wraps data types from the eight primitive data so that these can be used to create instantiated objects with methods in another class or in other classes. The primitive wrapper classes are found in the Java API.”

The primitive data type must be converted to it’s corresponding wrapper class, because the object is necessary to modify the argument or parameter passed into the method.

Collection framework such ArrayList, Vector store only the objects, not primitive data types so it must be converted to its corresponding wrapper class.

It is a process by which we can convert primitive data types into object types. Every primitive data type has its own wrapper class.

Primitive Type	Wrapper class
boolean	Boolean
char	Character
byte	Byte
short	Short
int	Integer
long	Long
float	Float
double	Double

All the wrapper class is the subclasses of the abstract number class.

Java data types are primitive by default and sometimes we require to represent as an object so we need to wrap the primitive data type in a class.

class WrapperClassExample

{

public static void main(String[] args)

{

String a = "20";

String b = "30";

int f1, f2, result;

System.out.println("Sum before:"+ a + b); // print 2030 not 50

f1 = Integer.parseInt(a); // convert String to int type

f2 = Integer.parseInt(b); // convert String to int type

result = f1 + f2;

System.out.println("sum after: " + result); // 50

}

}

public class Example {
  public static void main(String[] args) {
    Integer intEx = 10;
    Double doubleEx = 8.87;
    Character charEx = 'C';
    System.out.println(intEx);
    System.out.println(doubleEx);
    System.out.println(charEx);
  }
}

Boxing-UnBoxing in Java is used to automatically convert the primitive data types into its corresponding objects.

Some More Java Topics
Autoboxing and Unboxing in java
JAVA QUESTIONS AND ANSWERS FOR BEGINNERS

Sample output

Sum before:2030

sum after: 50