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Thread: Bubble Sort with random numbers

  1. #1
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    Mar 2011
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    Default Bubble Sort with random numbers

    Hi I am pretty new to java and one of my assignments in university is causing me a problem and I just can't seem to figure out where i'm going wrong.

    My specification is:

    1] Creating a real random number between "0" and "20" using the "Random" constructor with a seed of 123456
    2] Creating an array of 30000 different random numbers using this seed
    3] Using a bubble sort (without using the "java.util.Arrays.sort" or "java.util.Collections.sort" methods) to identify the highest 10 elements of that array.
    4] Printing out those 10 figures to screen.

    The code I have made so far is:
    import java.util.Random;
    public class BubbleSort{
      public static void main(String a[]){
    	  Random rndNumbers = new Random();
          int rndNumber = 0;
          for (int nbr = 0; nbr < 10; nbr++) {
              rndNumber = rndNumbers.nextInt(3000);
              System.out.println("Number: " + rndNumber);
              int[] x = new int[6];
              for (int i=0; i<x.length; i++);
      int i;
      int array[] = {rndNumber};
      System.out.println("Values Before the sort:\n");
      for(i = 0; i < array.length; i++)
      System.out.print( array[i]+"  ");
      bubble_srt(array, array.length);
      System.out.print("Values after the sort:\n");
      for(i = 0; i <array.length; i++)
      System.out.print(array[i]+"  ");
      System.out.println("The bubble sort algorithm has put the random integers into order!");
      public static void bubble_srt( int a[], int n ){
      int i, j,t=0;
      for(i = 0; i < n; i++){
      for(j = 1; j < (n-i); j++){
      if(a[j-1] > a[j]){
      t = a[j-1];

    For some reason it is only generating one random number at a time. Can anybody help me please?
    Any help would be great, thanks!

  2. #2
    Join Date
    Aug 2011
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    Default Re: Bubble Sort with random numbers

    You should be held back a year in school there...

    But so that does not happen....

    import java.util.Random;
     ...edited by moderator

    Notice how I used just one array. Also you were seeding 3000 and creating random numbers from 1 to 123456. this has all been fixed.

    Now I'm gonna get yelled at for spoonfeeding you. I don't care. I was bored.

    Note: I've been doing java for only 14 days... I started programming in basic in 1986.
    Last edited by copeg; August 20th, 2011 at 09:39 AM.

  3. #3
    Administrator copeg's Avatar
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    Default Re: Bubble Sort with random numbers

    Quote Originally Posted by Spidey1980 View Post
    Now I'm gonna get yelled at for spoonfeeding you. I don't care. I was bored.
    Yes you are. And your post has been edited
    I recommend you read the forum rules, and the following:
    The Problem with Spoon-feeding

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