Question

How to chose only one picture which can’t repeat?

I tried this:

I use random and i want to delete selected picture

String[] picture = { "blue", "white", "red", "yellow" };

   int number_picture1; 

// Random function to find a random picture

   Random ran = new Random();

   number_picture1 = ran.nextInt(picture.length);

System.out.println(picture[number_picture1]);

// There is still posibility to chose the same picture

   int number_picture2; 

   number_picture2 = ran.nextInt(picture.length);

System.out.println(picture[number_picture2]);

Answer 1

Simplest way is to use a List¹ to store your elements, and use Collections.shuffle() on it – and then take elements iteratively.

The shuffle produces a random permutation of the list, so chosing items iteratively gives you the same probability to chose any ordering, which seems to be exactly what you are after.

Code snap:

String[] picture = { "blue", "white", "red", "yellow" };
//get a list out of your array:
List<String> picturesList = Arrays.asList(picture);
//shuffle the list:
Collections.shuffle(picturesList);
//first picture is the first element in list:
String pictureOne = picturesList.get(0);
System.out.println(pictureOne);
//2nd picture is the 2nd element in list:
String pictureTwo = picturesList.get(1);
System.out.println(pictureTwo);
...

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(1) Simplest way to get the list from an array is using Arrays.asList()