Java : string operators precedence == vs +

Question

Can someone please explain to me why this code print only false (Not Both are equal: false)

String one = "length: 10";
String two = "length: " + one.length();
System.out.println("Both are equal:" + one == two);

@Hülya The OP's question is about why the output is `false` and not `Both are equal: false`. Although comparing strings with `==` is typically wrong, this question is more about how string concatenation works. — Slaw, Dec 30 '20 at 09:34
But still duplicate :) : https://stackoverflow.com/q/18238056/10367471 — Hülya, Dec 30 '20 at 10:28

score 4 · Answer 1 · answered Dec 30 '20 at 08:34

System.out.println("Both are equal:" + one == two);

is evaluated as

System.out.println(("Both are equal:" + one) == two);

i.e. first one is appended to "Both are equal:" , which results in the String "Both are equal:length: 10", and then that String is compared to two, which results in false, so only false is printed.

What you want is

System.out.println("Both are equal:" + (one == two));

score 1 · Accepted Answer · answered Dec 30 '20 at 09:05

1

Just put the brackets here:

System.out.println("Both are equal:" + (one == two));

answered Dec 30 '20 at 09:05

Piaget Hadzizi

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Java : string operators precedence == vs +

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