Why can not I add two bytes and get an int and I can add two final bytes get a byte?

by

From the JLS 5.2 Assignment Conversion

In addition, if the expression is a constant expression (ยง15.28) of type byte, short, char, or int:
– A narrowing primitive conversion may be used if the type of the
variable is byte, short, or char, and the value of the constant
expression is representable in the type of the variable.

In short the value of the expression (which is known at compile time, because it is a constant expression) is representable in the type of the variable that is byte.

Consider your expression 

 final byte x = 1;
 final byte y = 2;
 byte z = x + y;//This is constant expression and value is known at compile time

So as summation fits into byte it does not raise an compilation error.

Now if you do

final byte x = 100;
final byte y = 100;
byte z = x + y;// Compilation error it no longer fits in byte

More Related Contents:

  1. Java – char, int conversions
  2. Why does Double.NaN==Double.NaN return false?
  3. Java SneakyThrow of exceptions, type erasure
  4. Slight confusion regarding overriding where variables are concerned
  5. Why can't we declare variables in if statement?
  6. Java > Generate a lot of int
  7. Why don’t Java’s +=, -=, *=, /= compound assignment operators require casting?
  8. Why can’t I do assignment outside a method?
  9. What’s the best way to check if a String represents an integer in Java?
  10. In Java, is the result of the addition of two chars an int or a char?
  11. Convert int to char in java
  12. The literal xyz of type int is out of range
  13. In java, is it more efficient to use byte or short instead of int and float instead of double?
  14. Java, Simplified check if int array contains int
  15. Java Round up Any Number
  16. Why is assignment to ‘this’ not allowed in java?
  17. Java unreachable catch block compiler error
  18. How do I copy the contents of one ArrayList into another?
  19. How to Convert Int to Unsigned Byte and Back
  20. Return first digit of an integer
  21. Java – Change int to ascii
  22. ClassCastException because of classloaders?
  23. Why does integer division by zero 1/0 give error but floating point 1/0.0 returns “Inf”?
  24. negative char Value JAVA
  25. How can I convert a Java HashSet to a primitive int array?
  26. Unexpected result in long/int division
  27. Java Operators : |= bitwise OR and assign example [duplicate]
  28. Priority queue ordering of elements
  29. Java – When is it a compiler error and when is it a runtime exception?
  30. Why don’t Java’s +=, -=, *=, /= compound assignment operators require casting long to int?

Leave a Comment