How to do the sorting for duplicate numbers in Java?

Question

Now I want to do the sorting part... What is sort? And I so confused about sorting and I need to remove the duplicate numbers... And how to do remove numbers and sort for this coding? p/s:The duplicate numbers I only got a few...

import java.lang.*; 
// import java.util.Random;

class UniqueRandomIntArray {

//   static Random rnGen = new Random();

   private static void uriArray(int[] rray) {
      int low = 0;
      int high = 100;

      int rn;
      int haveit = -1;
      int i = 0; 
      int j;

      while((haveit == -1) && i < rray.length) {  
         rn = randNum(low, high);

         for(j = 0; j <= i; j++) {
            if(rn == rray[j]) {
               haveit = j;
               j = i;
               }
            }

         if(haveit != -1) {
            System.out.println("a[" + haveit + "] is " + rn + " already");
            haveit = -1;
            }
         else {
            System.out.println("a[" + i + "] is " + rn);
            rray[i] = rn;
            i++;
            }

         }   // end while
      }      // end uriArray


   private static int randNum(int min, int max) {
      int range = (max - min) + 1;
//      int randnum = rnGen.nextInt(range) + min;
      int randnum = (int) (Math.random() * range) + min;
      return randnum;
      }


   public static void main(String[] args) {
      int[] arra = new int[20];
      uriArray(arra);
      for(int i=0; i<arra.length; i++)  {
         System.out.print(" | " + arra[i]);
         }
      System.out.println(" | ");
      }

   } //class ends

Possible duplicate of http://stackoverflow.com/questions/19441276/duplicates-in-a-sorted-java-array — Sheetal Mohan Sharma, Jun 11 '15 at 13:34
Why dont you use a `set` which doesn't allow duplicate entries. — Uma Kanth, Jun 11 '15 at 13:34

griFlo · Answer 1 · 2015-06-11T13:55:35.510

2

Here is an easy way to generate a unique, random list of ints:

    new Random().ints(0, 101)// generate a stream of random integers from 0 (incl.) to 100
            .distinct() // unique                                   
            .limit(20) // we only need 20 random numbers
            .sorted() // sort
            .forEach(System.out::println);

So if you want the same result as in your old code, this is your complete new code:

class UniqueRandomIntArray {
public static void main(String[] args) {
    new Random().ints(0, 101).distinct() // generate a stream of random
            // integers
            .limit(20) // we only need 20 random numbers
            .sorted().forEach((int i) -> System.out.print(" | " + i));
    System.out.println(" | ");
}
} // class ends

edited Jun 11 '15 at 13:55

answered Jun 11 '15 at 13:38

griFlo

2,084
18
28

So this the new array or I have to put this inside the code? – Cracker Rex Jun 11 '15 at 13:41
@RexYou do you need the array? you can change the code above. instead of .forEach(...) you can write .boxed().collect(Collectors.toList());. This gives you a List of Integers. you can convert it to an array if you really need it – griFlo Jun 11 '15 at 13:48
But I don't know where to change? – Cracker Rex Jun 11 '15 at 13:55
@RexYou I've updated my answer. ask if you need more than that. – griFlo Jun 11 '15 at 14:04

divine · Answer 2 · 2015-06-11T14:16:10.113

0

Replace below code with your current main method and run the program.
for ascending order result use this
Arrays.sort(result);

for descending order result use both
Arrays.sort(result);
Arrays.sort(result, Collections.reverseOrder());

 public static void main(String[] args) {
      int[] arra = new int[20];
      uriArray(arra);

      Integer[] result = new Integer[arra.length];
        for (int i = 0; i < arra.length; i++) {
            result[i] = Integer.valueOf(arra[i]);
        }       
      Arrays.sort(result);          
      Arrays.sort(result, Collections.reverseOrder());  //comment this line if you want only ascending order results. if you want descending order result keep this line alive

      for(int i=0; i<result.length; i++)  {
         System.out.print(" | " + result[i]);
         }
      System.out.println(" | ");
      }

Let me know if this works for you

Include these packages

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

edited Jun 11 '15 at 14:16

answered Jun 11 '15 at 14:00

divine

4,746
3
27
38

The arrays didn't work so what is your suggestion?Main.java:56: error: cannot find symbol Arrays.sort(result); ^ symbol: variable Arrays location: class UniqueRandomIntArray Main.java:57: error: cannot find symbol Arrays.sort(result, Collections.reverseOrder()); ^ symbol: variable Collections location: class UniqueRandomIntArray Main.java:57: error: cannot find symbol Arrays.sort(result, Collections.reverseOrder()); ^ symbol: variable Arrays location: class UniqueRandomIntArray – Cracker Rex Jun 11 '15 at 14:11
did you include these packages? import java.util.ArrayList; import java.util.Arrays; import java.util.Collections; import java.util.List; – divine Jun 11 '15 at 14:12
which editor are you using for development?...are you using any IDE for development like eclipse ? – divine Jun 11 '15 at 14:13
include the above packages I mentioned and run the program..it will work.. I have updated it in my answer also – divine Jun 11 '15 at 14:15
Thank you very much... I want to ask you something.... Last time I use the Collections.shuffle didn't useful just because I didn't import? – Cracker Rex Jun 11 '15 at 14:16
yes I guess...what was the error? ... which editor are you using for development? – divine Jun 11 '15 at 14:19
I use for random choose number...the error same as just now...THANK YOU VERY MUCH... – Cracker Rex Jun 11 '15 at 14:23

How to do the sorting for duplicate numbers in Java?

2 Answers2