Re:In Java 3 = 12
by rusk on Wednesday November 15, 2017 @03:32AM
(#15702318)
I had to look twice at this. I was surprised that I could add the string “=“ to ‘3’. I guess what’s happening here is the int gets boxed and then gets implicitly converted to String. Proof of the pudding would be to try it with a simple string assignment rather than System.out.println. What happens after the “=“ is more straightforward
[ Parent
| on HN ]
This code gives the same result:
String splat = 1 + 2 + " = " + 1 + 2;
System.out.println(splat);
The JLS spec [0] accounts for this in its treatment of the '+' operator:
"If the type of either operand of a + operator is String, then the operation is string concatenation."
This does seem like idiosyncratic behaviour for java to be honest.
I don't think it's the compiler doing it either, because this will throw a null-pointer exception:
Integer borken = null;
String splat = borken + 2 + " = " + 1 + 2;
System.out.println(splat);
Plus.java:8: error: bad operand types for binary operator '+'
String splat = borken + 2 + " = " + 1 + 2;