Using Comparator to Sort an Array example in java

Using Comparator to Sort an Array

It offers an interface , called Comparator that is useful to impose a total ordering on a collection of elements.It can be used to sort the elements of an array into ascending order or descending order.

interface Comparator<T>,where T is generic type

Program Sample:

/**
 * 
 */
package com.collectionpack;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.Comparator;

/**
 * @author Abhinaw.Tripathi
 *
 */
class Ascending implements Comparator<Integer>
{

@Override
public int compare(Integer o1, Integer o2)
{

return o1.compareTo(o2);
}

}

class Desending implements Comparator<Integer>
{

@Override
public int compare(Integer o1, Integer o2)
{
return o2.compareTo(o1);
}

}

public class ComparatorApp
{
public static void main(String[] args) throws NumberFormatException, IOException
{
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
System.out.println("How many elements? ");
int size=Integer.parseInt(br.readLine());

Integer arr[] =new Integer[size];

for(int i=0;i<size;i++)
{
System.out.println("Eneter int: ");
arr[i]=Integer.parseInt(br.readLine());
}

Arrays.sort(arr, new Ascending());
System.out.println("Sorted in asending order");
display(arr);

Arrays.sort(arr,new Desending());
System.out.println("sorted in desending order");
display(arr);
}

private static void display(Integer[] arr)
{
for(Integer i:arr)
System.out.println(i + "\t");

}


}

Output:

How many elements? 

5

Eneter int: 

26

Eneter int: 

89

Eneter int: 

69

Eneter int: 

78

Eneter int: 

456

Sorted in asending order

26

69

78

89

456

sorted in desending order

456

89

78

69

26