reversing order of ArrayList

Question

I need to write a method that takes an arraylist of Strings and returns a new arraylist of strings where the elements are in reversed order. The original list needs to stay the same. any tips on how to handle this? any help would be great! thanks!

public static ArrayList<String> reverse(ArrayList<String> list) {
    //Note:  original 'list' must remain unchanged!!

    }

    //dummy return value
    return new ArrayList<String>();
}

Stack Overflow is not where people will do your homework for you, although we may help if you are stuck. What have you got so far? — user253751, Feb 10 '15 at 01:21
This question has been asked before: http://stackoverflow.com/questions/2137755/how-do-i-reverse-an-int-array-in-java — MFazio23, Feb 10 '15 at 01:23

score 4 · Answer 1 · answered Feb 10 '15 at 01:23

4

Copy the input List, and then use Collections.reverse(List). Something like

public static <T> List<T> reverse(List<T> list) {
    List<T> al = new ArrayList<>(list);
    Collections.reverse(al);
    return al;
}

answered Feb 10 '15 at 01:23

Elliott Frisch

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reversing order of ArrayList

1 Answers1