Stop picking the same data twice-CodePudding

How exactly do I create my code from selecting the same item twice from the array?

Example:

it'll print something like this "Gloria Gloria la Cinq Conflict"

How Do I stop it from doing that? Thanks in Advance

public class Main {

    public static void main(String[] args) {
        // The pump data consist of ONLY D24 PumpItUp charts

        Random rand = new Random();


        String[] PumpData = {"la Cinq", "Gloria", "Vanish", "Harma", "Conflict", "Sarabande", "Bedlam", "Final Audition", "Achluoias", "FFF", "Full moon", "Full moon FULL", "Annihilator" , "Creed FULL" , "BrainPower", "lolite", "Dement", "Destri", "Cross Soul", "TFTMN FULL", "Errorcode", "Dignity", "A Site De La Rue", "Trashy", "Paved Garden", "V3"};

        for (int i = 0 ; i < 4; i  ){
            int rand_int = rand.nextInt(5);
            String ChooseDeath = (PumpData[rand_int]);
            System.out.println(ChooseDeath);
        }
    }

}

CodePudding user response：

You can maintain a set that keeps track of all chooseDeath String. Before printing it ,you can just verify whether the set contains it or not. The question arises , what do you want to do in case a duplicate occurs, do you want to still print 4 words or less words . I have shown the implementation which picks 4 words everytime.

public class SetTest {

  public static void main(String[] args) {
      // The pump data consist of ONLY D24 PumpItUp charts

      Random rand = new Random();


      String[] PumpData = {"la Cinq", "Gloria", "Vanish", "Harma", "Conflict", "Sarabande", "Bedlam", "Final Audition", "Achluoias", "FFF", "Full moon", "Full moon FULL", "Annihilator" , "Creed FULL" , "BrainPower", "lolite", "Dement", "Destri", "Cross Soul", "TFTMN FULL", "Errorcode", "Dignity", "A Site De La Rue", "Trashy", "Paved Garden", "V3"};
      Set<String> set = new HashSet<>();
      for (int i = 0 ; i < 4; i  ){
          int rand_int = rand.nextInt(5);
          String chooseDeath = (PumpData[rand_int]);
          if(!set.contains(chooseDeath))
          {
           set.add(chooseDeath); 
           System.out.println(chooseDeath);
          }
          else {
            i--; 
            continue; 
          }
          
      }
  }

}

this will give the following output :

Conflict
Gloria
Harma
Vanish

CodePudding user response：

You need to keep track of what you've already selected. Something like:

Random rand = new Random();
Set<Integer> visited = new HashSet<>();

String[] PumpData = {...};

for(int i = 0; i < 4; i  )
{
    int rand_int = rand.nextInt(5);
    while(visited.contains(rand_int))
    {
        rand_int = rand.nextInt(5);
    }
    System.out.println(PumpData[rand_int];
    visited.add(rand_int);
}

CodePudding user response：

Plenty of answers already. I just want to add a solution using Streams.

new Random().ints(0, pumpData.length) // Create IntStream of random numbers between 0 and pumpData.length
    .distinct() // Remove duplicates from the stream
    .limit(4) // Limit stream to 4 numbers
    .mapToObj(i -> pumpData[i]) // Map IntStream to Stream<String> using the words in the array
    .forEach(System.out::println); // Print all the Strings

CodePudding user response：

You should store selected values in a Collection since collections has "is exists" or not function. I'd suggest you to store in a HashMap since it has O(1) access time or List.
after each drawing you can question whether I selected this value before or not.