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Wrapper Class Problem

 
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Please correct me ,can I do something like this .

1: Byte b =new Byte((byte) 8);
Byte b1=new Byte(b);//2


2: Byte b =new Byte((byte) 8);
byte byteval=b;

3:
// this is the example from K&B book which says an error at line 1
but if I try to compile it executes fine .

a) int intval=Integer.valueOf("345");//line 1
System.out.println(intval);

b) Float f=new Float(12.3);
float f1=Float.valueOf(23.4f);
 
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Originally posted by Kasak Tahilramani:
Please correct me ,can I do something like this .

1: Byte b =new Byte((byte) 8);
Byte b1=new Byte(b);//2


2: Byte b =new Byte((byte) 8);
byte byteval=b;

3:
// this is the example from K&B book which says an error at line 1
but if I try to compile it executes fine .

a) int intval=Integer.valueOf("345");//line 1
System.out.println(intval);

b) Float f=new Float(12.3);
float f1=Float.valueOf(23.4f);



The valueOf methods of Integer return a reference to an Integer object. If you are using a JDK >= 1.5, then autoboxing will automatically convert the Integer to an int.

However, if you use a JDK < 1.5, then you will get a compile-time error on line 1.

The same thing is true for Byte. JDK >= 1.5 will automatically convert a Byte to a byte.

Also if JDK >= 1.5, then a Byte will automatically be converted to a byte so that you can call the constructor of Byte that accepts a byte.
[ December 31, 2006: Message edited by: Keith Lynn ]
 
It is sorta covered in the JavaRanch Style Guide.
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