Primitive type

Question

Hello, pls help me on this:
Q1:
a portion of java code:
1. short s = 1;
2. int n = 1;
3. byte b1 = s;
4. byte b2 = n;
The compiler error occurs on line 3. Why happen to short but not int?
Q2:
When to use NaN?

Answer 1

Hello, pls help me on this:
Q1:
a portion of java code:
1. short s = 1;
2. int n = 1;
3. byte b1 = s;
4. byte b2 = n;
The compiler error occurs on line 3. Why happen to
short but not int?It does happen for int as well. If you comment out line 3, you will get an error on line 4.
The reason is that a byte can not hold all the values that a short or an int can hold, so you have to "tell the compiler" that you know what you're doing (either you have ensured that the value will be within the correct range, or you don't care about any loss of precision due to truncation). Although it may be clear to you from the code that the value being assigned is inside the range of values representable with a byte, the compiler does not attempt to perform any such analysis - the only time you can assign an int or short to a byte variable without an explicit cast is when the value is the result of a compile-time constant expression (thus if you make both s and n final, the compiler error will go away).
(see the JLS for a definition of compile-time constants).