about 9 years ago
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 | Wrapper class |
|---|---|
| boolean | Boolean |
| char | Character |
| byte | Byte |
| short | Short |
| int | Integer |
| long | Long |
| float | Float |
| double | Double |
Converting Primitive to Wrapper:
public class PrimitivetoWrapper{public static void main(String args[]){int m=10;Integer i=Integer.valueOf(m);//converting int into IntegerInteger j=m;//autoboxing, compiler will write Integer.valueOf(m) internallySystem.out.println(m+" "+i+" "+j);}}
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 intint j=m;//unboxing, now compiler will write m.intValue() internallySystem.out.println(m+" "+i+" "+j);}}
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.
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