Looking for good table with all Java operators
in [Java Help]
|
Prev: ?k???O?T?h???C
Next: JVM and java application
From: Mike Schilling on 25 Jan 2010 22:13 Lew wrote: > Mike Schilling wrote: >> Lew wrote: >> >>> However, the JLS does refer to 'instanceof' as an >>> operator. >> >> But it's not in the list of operators, so the JLS contradicts >> itself. >> It really is the Java programmer's Bible! >> >> More seriously, the official JLS definition of "operator" describes >> only operators made up of special characters; that is, it >> distinguishes "operator" from "keyword". > > I was just going by > <http://java.sun.com/docs/books/jls/third_edition/html/expressions.html#15.20.2> > entitled "Type Comparison Operator instanceof". That looks an awful > lot like an "official JLS definition" to me. Sorry, I meant that 15.20.2 disagrees with the list in 3.12. Which is fine; it's not as if giving a precise defintions of "operator" is one of the JLS's most important goals. This reminds me of a discussion that went on in comp.lang.c years ago. Someone was asking whether "3 + 12i" was an imaginary number or not. He'd seen some references that said "3 + 12i" was imaginary but not "pure imaginary", and others that said "3 + 12i" was not imaginary because it had a real part. He wanted to know the answer, because, dammit, in mathematics there's always one right answer. No one could convince him otherwise.
From: Patricia Shanahan on 25 Jan 2010 22:31 Robbo wrote: .... > 1. According to some resources, postfix and prefix > have the same level (precedence). It is right? .... ++(a--) and (++a)-- both apply an operator requiring a variable to a non-variable value. ++a-- is an error. Patricia
From: Lew on 25 Jan 2010 22:37 Mike Schilling wrote: > This reminds me of a discussion that went on in comp.lang.c years ago. > Someone was asking whether "3 + 12i" was an imaginary number or not. > He'd seen some references that said "3 + 12i" was imaginary but not > "pure imaginary", and others that said "3 + 12i" was not imaginary > because it had a real part. He wanted to know the answer, because, > dammit, in mathematics there's always one right answer. No one could > convince him otherwise. That was a much more complex question, though. -- Lew
From: Robbo on 26 Jan 2010 06:30 > Actually, UnaryExpressionNotPlusMinus contains CastExpression, so it is > actually at the same precedence level as logical and bitwise NOT, which > is one higher than the prefix/unary +/unary - (UnaryExpression contains > PreIncrementExpression, PreDecrementExpression, and the unary +/unary -). UnaryExpressionNotPlusMinus contains PostFixExpression also. To be honest, I do not understand Your sentence above. Does it mean that "cast" is at the same level as ~ and ! but there should be one more level (above ~ ! and cast) with unary +/-/--expr/++expr? 1. expr++, expr-- 2. ++expr, --expr, +expr, -expr 3. ~ ! (type)
From: Robbo on 26 Jan 2010 06:31
> As I was corrected upthread (perhaps you missed that post), there is no > associativity for postfix operators. Ok. Thx. Level Category Operator Associativity --------------------------------------------------------------- 1 postfix expr++ expr-- + --------------------------------------------------------------- 2 prefix ++expr --expr right+ unary +expr -expr logical NOT ! bitwise NOT ~ --------------------------------------------------------------- 3 cast (type) right+ --------------------------------------------------------------- 4 multiplicative * / % left+ --------------------------------------------------------------- 5 additive + - left+ --------------------------------------------------------------- 6 shift << >> >>> left+ --------------------------------------------------------------- 7 relational < <= > >= left+ type comparison instanceof --------------------------------------------------------------- 8 equality == != left+ --------------------------------------------------------------- 9 bitwise AND & left+ --------------------------------------------------------------- 10 bitwise XOR ^ left+ --------------------------------------------------------------- 11 bitwise OR | left+ --------------------------------------------------------------- 12 logical AND && left+ --------------------------------------------------------------- 13 logical OR || left+ --------------------------------------------------------------- 14 conditional ?: right+ --------------------------------------------------------------- 15 assignment = += -= *= /= right+ %= &= ^= |= <<= >>= >>>= --------------------------------------------------------------- |