How Java concatenates String with boolean?

Question

I fail to understand the outputs below:

System.out.println(s1.equals(s2)+"a");  ->truea

System.out.println(s1==s2+"a");         ->false

Where s1 & s2 are declared as same String "abc" i.e String s1="abc"; String s2="abc";

possible duplicate of [Java comparison with == of two strings is false?](http://stackoverflow.com/questions/995918/java-comparison-with-of-two-strings-is-false) — Woot4Moo, Dec 01 '13 at 14:10
@Woot4Moo This is about operator precedence, not string equality. — Boann, Dec 02 '13 at 22:12

eugene82 · Accepted Answer · 2013-12-01T14:14:58.127

6

s1==s2+"a"

means the same as

s1==(s2+"a")

because == has lower precedence than +.

edited Dec 01 '13 at 14:14

answered Dec 01 '13 at 14:08

eugene82

score 3 · Answer 2 · edited Dec 03 '13 at 00:58

3

According to the Oracle documentation the + operator has higher precedence than equality check.

edited Dec 03 '13 at 00:58

n00begon

answered Dec 01 '13 at 14:09

Artem Moskalev

score -3 · Answer 3 · answered Dec 01 '13 at 14:09

-3

Because s1 is one string object while s2 is another string object. They have different memory addresses.

answered Dec 01 '13 at 14:09

LuckyLuke

It is not really true. String literals are stored in small tables, and new variables are given access to those. It means that if you declare it like new String("abc") == new String("abc"), it will give false, but in the OP question it should give true. – Artem Moskalev Dec 01 '13 at 14:11
@ArtemMoskalev it definitely should not. – Woot4Moo Dec 01 '13 at 14:12
3

@Woot4Moo, String a = "abc"; String b = "abc"; a == b gives true. You can check. – Artem Moskalev Dec 01 '13 at 14:13

3 Answers3