Random Numbers on button

[daina]

Hi,

I was wondering how do i go about generating unique random numbers?
ie
i want to generate numbers between 0-9 randomly. I dont want to repeat the numbers.Then that no: should display on the buttons.ie there are 9 buttons. first randomly generated number should display on the first button & 2nd no: should display on 2nd button. & so on for example I have the numbers 9371482065 then 9 should display on the first button ,3 should display on 2nd button ....
But the following code i'm having is repeating some numbers...can any one help me in solving...please.....


code::::


Random rgen = new Random(); // Random number generator
int[] cards = new int[10];

// --- Initialize the array to the ints 0-51
for (int i=0; i<10; i++) {
cards[i] = i;
}

// --- Shuffle by exchanging each element randomly
for (int i=0; i<10; i++) {
int randomPosition = rgen.nextInt(10);
System.out.println(" randomPosition " + randomPosition);
int temp = cards[i];
System.out.println(" temp" + temp);
cards[i] = cards[randomPosition];
cards[randomPosition] = temp;

System.out.println(" Random Number" + cards[randomPosition]);

}

[Wizard1988]

Computers can't generate real random numbers but you can get some real random numbers here http://www.fourmilab.ch/hotbits/

[sjalle]

The idea is to stuff the random numbers into a HashSet as you go along.
When the size of the hashset is 10 you know that it contains 10
unique integers.

import java.util.*;

public class Ramdomizer {
  public static Random rand=new Random(System.currentTimeMillis());
  static HashSet hs=new HashSet();

  public Ramdomizer() {}

  public int [] getRandoms(int maxNo) {
    hs.clear();
    while (true) {
      int n = rand.nextInt(maxNo);
      hs.add(new Integer(n));
      if (hs.size() == maxNo) {
        break;
      }
    }
    int [] ret=new int[maxNo];
    Iterator it=hs.iterator();
    int cnt=0;
    while (it.hasNext()) {
      ret[cnt++]=((Integer)it.next()).intValue();
    }
    return shuffle(ret);
  }

  private int [] shuffle(int [] arr) {
    for (int i=0; i<arr.length; i++) {
      int rp = rand.nextInt(10);
      int tmp=arr[rp];
      arr[rp]=arr[i];
      arr[i]=tmp;
    }
    return arr;
  }
  /**
   * *********** MAIN ***********
   */
  public static void main(String[] args) {
    Ramdomizer rd = new Ramdomizer();
    int [] rn=rd.getRandoms(10);
    showResult(rn);
    rn=rd.getRandoms(10);
    showResult(rn);
  }
  private static void showResult(int[] rn) {
    for (int i=0; i<rn.length; i++) {
      System.out.println(i+": "+rn[i]);
    }
  }
}

[mohit]

Hi,

I was wondering how do i go about generating unique random numbers?
ie
i want to generate numbers between 0-9 randomly. I dont want to repeat the numbers.Then that no: should display on the buttons.ie there are 9 buttons. first randomly generated number should display on the first button & 2nd no: should display on 2nd button. & so on for example I have the numbers 9371482065 then 9 should display on the first button ,3 should display on 2nd button ....
But the following code i'm having is repeating some numbers...can any one help me in solving...please.....


code::::


Random rgen = new Random(); // Random number generator
int[] cards = new int[10];

// --- Initialize the array to the ints 0-51
for (int i=0; i<10; i++) {
cards[i] = i;
}

// --- Shuffle by exchanging each element randomly
for (int i=0; i<10; i++) {
int randomPosition = rgen.nextInt(10);
System.out.println(" randomPosition " + randomPosition);
int temp = cards[i];
System.out.println(" temp" + temp);
cards[i] = cards[randomPosition];
cards[randomPosition] = temp;

System.out.println(" Random Number" + cards[randomPosition]);

}

Read your code again. Its perfect! You just need to print the cards array in another loop after the first for loop and you will get desired result.

Regards,
Mohit