randomGenerator避免连续重复

Question

I have a question regarding the following code

Random randomGenerator = new Random();
    int randomInt = randomGenerator.nextInt(4);
    String wordList[] = new String[4];
    {
        wordList[0] = "Red";
        wordList[1] = "Blue";
        wordList[2] = "Green";
        wordList[3] = "Orange";


    }

String wordToDisplay = wordList[randomInt];

This code works fine however I would like to know if it was possible to get it to not pick the same word two times in a row. For example, if it just selected "Red" then it would not pick "Red" again the next consecutive time. I read something about DISTINCT but I'm not sure if that's along the right path.

Here is the code for the button which uses this

final Button button1 = (Button) findViewById(R.id.button1);
        final TextView textView = (TextView) findViewById(R.id.text_random_text);
        button1.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                // Perform action on click
                Random randomGenerator = new Random();
                int randomInt = randomGenerator.nextInt(9);
                String wordToDisplay = wordList[randomInt];
                textView.setText(wordToDisplay);

Thankyou for your help

Answer 1

go for list and remove color once used:

private static ArrayList<String> arrayList = new ArrayList<String>();
private static Random random = new Random();
public static void fillList(){
    arrayList.add("Red");
    arrayList.add("Blue");
    arrayList.add("Green");
    arrayList.add("Orange");
}
public static String getNextRandomColor(){
    if(arrayList.isEmpty()){
        fillList();
    }
    return arrayList.remove(random.nextInt(arrayList.size()));
}

Answer 2

You can do this in two way (probably more but two that I can think of right now):

1) Create a function that uses a global variable to store the last generated random number. It will look something like this:

int myRand(int i) {
  int aux;
  Random randomGenerator = new Random();

  do {
    aux = randomGenerator.nextInt(i);
  } while (aux != lastRandGenerated);

  lastRandGenerated = aux;

  return aux;
}

, where lastRandGenerated is a global variable that you initialize to 0.

Then you use this function to generate random numbers.

2) You can create a class that has a function very similar to the one above and then instantiate an object of that class and use that to generate your random numbers. In the class create a static variable that will remember the last generated random number. Use that instead of the global variable.

Answer 3

The specifics are a bit out of my league but as a math problem there are 24 combinations (4 * 3 * 2 * 1). As heavy handed as this might sound, worst case you could work out all the combos and then pick a one out of 24 random.