Casting Difference of Float.POSITIVE_INFINITY

[Sandeep Chhabra]

Hi,
Consider the following Code:

public class test {
 
public static void main (String args []) {
 
float f=Float.POSITIVE_INFINITY;
byte b=(byte)f;
System.out.println(b);
 
int i=(int)f;
System.out.println(i);
}
}
 

This code compiles fine and gives the output :
----------------------------------------------
-1
2147483647
----------------------------------------------

Can anyone explain why there is difference between the result of two casting?

Thanx

Sandy

[Jimmy Thomas]

Sandy,

Try this

float f = Float.POSITIVE_INFINITY;
byte b = (byte) f;
System.out.println(b);
int i = (int) f;
byte b2 = (byte)i;
System.out.println(i);
System.out.println(b2);
System.out.println(Integer.toBinaryString(i));
System.out.println(Integer.toBinaryString(-1)); 
                System.out.println(Integer.MAX_VALUE);
 

Output:
----------------------------------
-1
2147483647
-1
1111111111111111111111111111111
11111111111111111111111111111111
2147483647

I guess this should explain... narrow conversion.
[ September 16, 2005: Message edited by: Jimmy Thomas ]

[Alexey Korneychuk]

I think
{byte b = (byte) f;} the same { byte b = (byte) (int)f;}

But not sure

[Barry Gaunt]

You would have expected that the byte cast would result in +127 (the maximum possible positive byte value). Horror!

I also suspect it's because casting to byte is done via a cast to int. That is Float.POSITIVE_INFINITY gets first cast to Integer.MAX_VALUE. Then the cast to byte just takes the least 8 bits of Integer.MAX_VALUE to get -1.

[Arun kumar]

public class Test
{
public static void main(String[] a)
{
float f = Float.POSITIVE_INFINITY;
byte b = (byte)f;
int i = (int)f;
short s = (short)f;
System.out.println(b);
System.out.println(s);
System.out.println(i);
System.out.println(f);

double d = Double.POSITIVE_INFINITY;
long l = (long)d;
int j = (int)d;
System.out.println(l);
System.out.println(j);

}
}
------------------ output ------------------
-1
-1
2147483647
Infinity
9223372036854775807
2147483647
---------------------------------------------

i was expecting -2147483648 for the last SOP. anyone please explain.

[Swathi Sree]

class Test1 {

public static void main(String[] args) {
System.out.println(Float.POSITIVE_INFINITY == Double.POSITIVE_INFINITY);
}
}

--------Output--------
true
----------------------

This would answer your question