Java String manipulation query using trim() and length() [duplicate]

Question

public class X {

    public static void main(String[] args) {

        String s1=" abc xyz ";
        System.out.println(s1.length());
        s1.trim();
        System.out.println(s1.length());
        System.out.println(s1.trim().length());
    }
}

O/p:

9
9
7

Kindly explain to me why s1.trim().length() is 7 and not 9 as s1 will still be pointing to the old string ie " abc xyz " ?

@devnull just checked your profile@SO, It is so funny that, in "about me" section we have "tried" to find the similar thing. :-D — Kent
– Kent, Commented May 13, 2014 at 8:29
@Duncan Yes, you weren't aware? You can use the hammer for closing a question containing a tag for which you have a gold badge. — devnull
– devnull, Commented May 13, 2014 at 8:30

TheLostMind · Accepted Answer · 2014-05-13 08:26:29Z

2

s1=s1.trim(); // trim() returns the "trimmed" String. You have to set it back to the reference

answered May 13, 2014 at 8:26

TheLostMind

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Comments

Sanjay Rabari · Accepted Answer · 2014-05-13 08:40:49Z

1

s1.trim(); does return trimmed string so capture in some variable to modify it.

in your case it left s1 as it is. so when you call s1.length() it provide original s1s length.

if you want to modify it try s1=s1.trim();

edited May 13, 2014 at 8:40

answered May 13, 2014 at 8:28

Sanjay Rabari

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Comments

rethab · Accepted Answer · 2014-05-13 08:25:12Z

0

Trim returns the new string rather than modifying it.

answered May 13, 2014 at 8:25

rethab

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