Question

I’m trying to make a method that returns a string of words in opposite order.

IE/ ‘The rain in Spain falls mostly on the’ would return: ‘the on mostly falls Spain in rain The’

For this I am not supposed to use any built in Java classes just basic Java.

So far I have:

    lastSpace = stringIn.length();       for (int i = stringIn.length() - 1; i >= 0; i--){         chIn = stringIn.charAt(i);         if (chIn == ' '){             word = stringIn.substring(i + 1, lastSpace);             stringOut.concat(word);             lastS = i;         }     }     word = stringIn.substring(0,lastSpace);     stringOut.concat(word);      return stringOut; 

My problem is when stringOut is returned to its caller it always is a blank string.

Am I doing something wrong? Maybe my use of string.concat()?

Answer 1

In Java, Strings are immutable, i.e. they can’t be changed. concat() returns a new string with the concatenation. So you want something like this:

stringOut = stringOut.concat(word); 

or

stringOut += word 

as Ray notes, there are more succinct ways to do this though.