primitive conversion and assignment

[Adolfo Eloy]

Hi.

Could someone help me to understand it please?

Please, look at comments on code...

public class Conversion {

	void sum(byte a, byte b) {
		byte r = (byte) (a + b);
		System.out.println("a + b = " + r);
	}
	
	public static void main(String[] args) {
		// why doesn't it compile?  
		new Conversion().sum(10, 10); // does not compile! why?

		// so why does it work! 
		// why the compile automatically converts 
		// 10 integer literal to byte (at assignments below)?
		byte x = 10; 
		byte y = 10;
		
		// now it works
		new Conversion().sum(x, y); 
	}
}

tks

[swaraj gupta]

Have a look at these points:

1> All the integer values are of type int by default.
2> Java does not support implicit narrowing of data types. (Compile time error otherwise)
3> But when a byte, short or char type variable is initialized with a "Constant Expression" and if the value is within the range of type concerned then ONLY implicit narrowing takes place.(Compile time error otherwise)

[Adolfo Eloy]

swaraj gupta wrote:Have a look at these points:

1> All the integer values are of type int by default.
2> Java does not support implicit narrowing of data types. (Compile time error otherwise)
3> But when a byte, short or char type variable is initialized with a "Constant Expression" and if the value is within the range of type concerned then ONLY implicit narrowing takes place.(Compile time error otherwise)

Swaraj, thanks for reply.

Considering the statement 3, I thought that the code below should compile because 10 can be narrowed to a byte.

new Conversion().sum(10, 10);

when I make the assignment of
byte b = 10; the compile narrowed it.


tks

[Rahul Saple]

But when a byte, short or char type variable is initialized with a non-long, compile-time, "Constant Expression" and if the value is within the range of type concerned then ONLY implicit narrowing takes place.(Compile time error otherwise)

The implicit narrowing conversion is only applicable within an assignment context and not any other(including method invocation context)