Primitive Casting

[Edward Seager]

Hi,

Why does the following code not compile (implicit cast from int to short)?

class Test {

	public static void main(String[] args) {
		foo(4);
	}
	
	static void foo(short p) {
		
	}

}

Whereas this works fine

class Test {

	public static void main(String[] args) {
		short foo = 4;
	}
}

Thanks,

[Ankit Garg]

Implicit downcast doesn't work in method calls i.e. parameters passed to methods...

[Tapio Niemela]

Ankit Garg wrote:Implicit downcast doesn't work in method calls i.e. parameters passed to methods...

Could you please describe what is an implicit downcast?

[Ankit Garg]

short s = 10;
final int i = 10;
short s2 = i;

In both the above cases, the int value is implicitly downcasted to short. The literal 10 is an int literal, which is implicitly downcasted to short in line 1. On line 3, the final constant i is implicitly downcasted to short...

[Abimaran Kugathasan]

Hi, Ankit Garg,
Since the variable i is a compile time constant, we can assigned it s2(should be within the range of short). OK.

But what about final wrapper objects? coding is below......

   
final Integer e = 100;
short x = (int)e; // No implicitly casting from int to short.
short y = (short)e; // in convertible types

.

[Ankit Garg]

As you said yourself, since i was a compile time constant, so it was automatically downcasted to short. Compile time constants are either of primitive types or String, other types of final variables are not compile time constants (including wrappers). This is why implicit downcast doesn't work on wrapper objects...

[Abimaran Kugathasan]

Ankit Garg wrote :

Compile time constants are either of primitive types or String, other types of final variables are not compile time constants (including wrappers)

Thanks a lot Ankit Garg for this valuable information.

Again Thanks to All.

[Abimaran Kugathasan]

Again one more question Ankit Garg,

Since interface accepts only constants, We can add wrapper objects as well. So there should be a difference between compile time constants and just constants? If so, how the just constants work? (At runtime???).

Thanks in Advanced.......!!!

[Abimaran Kugathasan]

There may be a difference,

final int a = 10;
final int b;

Here we should initialize b in every constructors. So a is a compile time constant and b is a just constant. Correct. Pleasse confirm!

[Neha Daga]

yes thats correct.

[Abimaran Kugathasan]

Thanks Nega Daga....

After long time you are here......... Happy to see you again here........ Thanks.

[Neha Daga]

yeah....was busy with some applications.