How to sort Integer Vector using Comparator and iterator?

Question

I want to create Integer vector type Vector and to insert random 10 numbers.

Then I want to sort the Vector by using compareTo and to send two arguments type numbers to compare it.

but I miss something. Many thanks for any help.

    import java.util.*;

public class SortNumeric implements Comparable<SortNumeric>
{
   private int ind =0;

   public static void main(String args[])
    {
        Vector<Integer> vec = new Vector<>();

        System.out.println("Befor sorting");
        for (int index = 0; index < 10; index++)
        {
            int rand = (int)(1000*Math.random());
            vec.add(rand);
             System.out.println(rand);
        }

        Arrays.sort(vec);

        System.out.println("After sorting");
        for(Integer intnum : vec)
         {
         System.out.println(intnum);
         }

    }

    public int getNextCompar(){
          if (vec.hasNext() && this.ind < 5){
            this.ind++;
            return vec.next();
        }else{return 0;}
     }

     public int compareTo(SortNumeric other)
            {
                return (int) (vec.next() - this.getNextCompar());

            }

}

Answer 1

class sortVectors implements Comparator<Integer>{

    @Override
    public int compare(Integer o1, Integer o2) {
        // TODO Auto-generated method stub
        if(o1<02){
            return -1;
        }else if(o1>o2)
            return 1;
            return 0;
    }
}
public class sortVector{
    public static void main(String[] args) {
        // TODO Auto-generated method stub
         Vector<Integer> vect = new Vector<Integer>();
            System.out.println("Befor sorting");
            for (int index = 0; index < 10; index++) {
                int rand = (int) (1000 * Math.random());
                vect.add(rand);
                System.out.println(rand);
            }
        Collections.sort(vect,new sortVectors());
        System.out.println("After Sorting");
        for (Integer num : vect) {
            System.out.println(num);
        }

    }

}

Answer 2

You don't need to implement Comparable for Integer, hence no compareTo is required. Also use Collections.sort instead of Arrays.sort. Here is your modified code example:

import java.util.Collections;
import java.util.Vector;

public class Main {
    public static void main(String args[]) {
        Vector<Integer> vec = new Vector<>();
        System.out.println("Befor sorting");
        for (int index = 0; index < 10; index++) {
            int rand = (int) (1000 * Math.random());
            vec.add(rand);
            System.out.println(rand);
        }

        Collections.sort(vec);

        System.out.println("After sorting");
        for (Integer intnum : vec) {
            System.out.println(intnum);
        }
    }
}

Check this SO question for more details:

What function can be used to sort a Vector?

Answer 3

If you want to sort an array in a specific order, you need to create a Comparator.

Comparable is used when you want to sort the objects of a particular class when used in a collection or array.

In your case, you need to use a Comparator.

class MyComparator extends Compartor
{
  public int compare(Integer a, Integer b)
  {
            return a - b;
  }
}

In your Main class, call Arrays.sort(vec, new MyComparator());