Question

I have used this question here on stackoverflow to create a random string without problem 😀
( Show random string)

Some times the same string shows up and that’s annoying.

So I want the string to only show one time per session, I have already a Quit Session button that kills the class. So lets say I have numbers from 1-3. Number 2 shows up first, then 1, becuase there’s only one number left only 3 can be shown.

My button code for the “next button”. Currently it kills the class and starts it again! How can I change it so it just displays a new string?

private void onButtonClick(Button clickedButton) {
    Intent startIntent = null;
    if (clickedButton.getId() == R.id.quit) {
        startIntent = new Intent(this, mainmenu.class);
        finish();
    }

    else if (clickedButton.getId() == R.id.next) {
         startIntent = new Intent(this, play.class);
         startActivity(startIntent); 
         finish(); 
    }

    if (startIntent != null) {
        startIntent.setFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
        startActivityIfNeeded(startIntent, 0);
    }
}
private void setupbutton() {        
    View.OnClickListener onClickHandler = new View.OnClickListener() {          

        public void onClick(View v) {
            onButtonClick((Button)v);               
        }
    };
    Button button = (Button)findViewById(R.id.quit);
    button.setOnClickListener(onClickHandler);

    button = (Button)findViewById(R.id.next);
    button.setOnClickListener(onClickHandler);

Answer 1

The same string is appearing because the random number generator generates random numbers! It could generate the same number multiple times in a row.

There are many possibilities, to name two:

1. Put all strings in an array and shuffle it. Then take the elements out one by one starting with index one:

   List strings = new ArrayList<String>(getResources().getStringArray(R.array.myArray));
   Collections.shuffle(list);
   

2. Put all strings in an array, select a string with a random index and remove the string:

       Random rgenerator = new Random();
   
       ArrayList<String> strings = new ArrayList<String>(getResources().getStringArray(R.array.myArray));                 
       int index = rgenerator.nextInt(strings.size());
       String randomString =  strings.get(index);
       strings.remove(index);
   

EDIT:
Ok, I see…

You have to remember which strings have not been used already. Store the strings in a List and make the list static, so you can save state between the creation of different instances of the Activityplay:

private static ArrayList<String> myString;

Then change your constructor a bit:

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.play);
    setupbutton();

    if (myString == null || myString.size() == 0) {
        Resources res = getResources();
        myString = new ArrayList(Arrays.asList(res.getStringArray(R.array.myArray)));
    }

    // get a random string
    int rand = rgenerator.nextInt(myString.size());
    String q = myString.get(rand);

    // remove the last used string from the list
    myString.remove(rand);

    TextView tv = (TextView) findViewById(R.id.text1);
    tv.setText(q);
}