final byte

[Ram Murthy]

public class Test8{
public static void main(String a[]){
byte b = 1;
char c = 2;
short s = 3;
int i = 4;

c = b; // 1
s = b; // 2
i = b; //3
}
}

The above code will not compile since at marker //1 it is trying to move a byte to char.
1. Not sure why it is not letting it even though byte is only 8 bits and char can hold upto 16 bits..

2. On the other hand if the byte declaration is changed to final byte =1 the code compiles...

Can anyone explain this..

Thanks
JP

[Ariel Ortiz]

  
public class Test8{
    public static void main(String a[]){
        byte b = 1;
        char c = 2;
        short s = 3;
        int i = 4;
 
        c = b; // 1
        s = b; // 2
        i = b; //3
    }
}

In //1, the compiler only knows that c is a char and b is a byte. The range of a char is 0 to 65535, and the range of a byte is -128 to 127. Values from -128 to -1 can't be represented with a char (buy they can with a byte). This is why the compiler complains.

Yet when you declare b to be final, the compiler knows that b will always be equivalent to the value 1 and that it will never change in all the program, thus it knows that it will always fit into a char variable.

Hope this clarifies.

...Ariel
[ October 12, 2005: Message edited by: Ariel Ortiz ]

[Ram Murthy]

Perfect it makes sense now. THANKS A BUNCH !!

[Roel De Nijs]

if you do explicit cast to char, it compiles also fine, even when your byte is negative (a question mark is printed)

 
public class Test8{
public static void main(String a[]){
byte b = -50;
char c = 2;
short s = 3;
int i = 4;
 
c = (char)b; // 1
s = b; // 2
i = b; //3
 
System.out.println(c + " | " + s + " | " + i);
System.out.println((byte)c + " | " + s + " | " + i);
}
 
}
 

output:
? | -50 | -50
-50 | -50 | -50
[ October 13, 2005: Message edited by: Roel De Nijs ]

[Andyjr Robinson]

Originally posted by JP Ravi:
public class Test8{
public static void main(String a[]){
byte b = 1;
char c = 2;
short s = 3;
int i = 4;

c = b; // 1
s = b; // 2
i = b; //3
}
}

The above code will not compile since at marker //1 it is trying to move a byte to char.
1. Not sure why it is not letting it even though byte is only 8 bits and char can hold upto 16 bits..

2. On the other hand if the byte declaration is changed to final byte =1 the code compiles...

Can anyone explain this..

Thanks
JP