It splits on every “\\S” which in regex engine represents \S non-whitespace character. So lets try to split “x x” on non-whitespace (\S). Since this regex can be matched by one character lets iterate over them to mark places of split (we will use pipe | for that). is ‘x’ non-whitespace? YES, so lets mark … Read more
Although the override is done properly for SubCovariantTest the answer is 5 because of how the variable c1 is declared. It is declared as a CovariantTest and not as a SubCovariantTest. When c1.getObject().x is run, it does not know that it is a SubCovariantTest (no casting was used). This is why 5 is returned from … Read more
If you compile it with -Xlint you’ll get a warning: c:\Users\Jon\Test>javac -Xlint SneakyThrow.java SneakyThrow.java:9: warning: [unchecked] unchecked cast throw (T) ex; ^ required: T found: Throwable where T is a type-variable: T extends Throwable declared in method <T>sneakyThrowInner(Throwable) 1 warning That’s basically saying “This cast isn’t really checked at execution time” (due to type erasure) … Read more
NaN means “Not a Number”. Java Language Specification (JLS) Third Edition says: An operation that overflows produces a signed infinity, an operation that underflows produces a denormalized value or a signed zero, and an operation that has no mathematically definite result produces NaN. All numeric operations with NaN as an operand produce NaN as a … Read more
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 … Read more