How do I shuffle two arrays in same order in java

Question

I\'ve got two arrays of question and answers

String questions[] = {
\"Q1?\",
\"Q2?\",
\"Q3?\"};

String answers[] = {
    \"A1?\",
    \"A2?\",
    \"A3?\"}         


        

Answer 1

Java Collections has a (surprisingly) simple solution to this problem: Collections.shuffle(Collection, Random) with a Random seeded with same seed.

    List quests = Arrays.asList(1, 2, 3, 4, 5);
    List answers = Arrays.asList(10, 20, 30, 40, 50);

    long seed = System.nanoTime();
    Collections.shuffle(quests, new Random(seed));
    Collections.shuffle(answers, new Random(seed));

    System.out.println(quests);
    System.out.println(answers);

Note:

Extra optimization is dangerous. This DOE NOT WORK:

    long seed = System.nanoTime();
    Random rnd = new Random(seed);
    Collections.shuffle(quests, rnd);
    Collections.shuffle(answers, rnd);

Originally posted at: https://stackoverflow.com/a/44863528/1506477