String s=" hello "; s+=" word "; s.trim(); System.out.println(s);

Question

why trim() not work here

Answer 1

trim() returns a String. It is not a void method since Strings are immutable.
So, you need to assign s to the value of trim().

Like this:

s = s.trim();

Answer 2

put them in String builder or buffer and then trim

Answer 3

what word u gonna trim here
u didn't mention