String concatenation showing unexpected behavior

Question

Bellow is snippet of my code. I just want to know why if condition is not being executed even if variable "ans" has value 2020.

private static void solve() throws Exception {
    
        String str="20";
        String str1="20";
        String ans=str+str1;
    
        if(ans=="2020")
         System.out.println("matched");
       else System.out.println("Not matched");

        System.out.println(ans);
}

Does this answer your question? [How do I compare strings in Java?](https://stackoverflow.com/questions/513832/how-do-i-compare-strings-in-java) — maloomeister, Dec 16 '20 at 07:53
yes actually equal method shows correct behavior but why in java == operator not showing correct behavior like c & c++ — Hrishi Bargal, Dec 16 '20 at 07:55

score 1 · Answer 1 · answered Dec 16 '20 at 07:53

1

ans.equals("2020")

this should work.

answered Dec 16 '20 at 07:53

Valeamor

53
1
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"2020".equals(ans) - this way there won't be NPE – PastorPL Dec 16 '20 at 07:55
Thanks for replying but could you please explain why == is not working like c++ – Hrishi Bargal Dec 16 '20 at 07:56
1

@HrishiBargal because A==B means A and B are the same object in java. ans = "20" + "20" create a new String object, the constant String "2020" is a different Object. – Valeamor Dec 16 '20 at 08:10

String concatenation showing unexpected behavior

1 Answers1