Sorting in Java is used to arrange elements in a specific order (ascending or descending). It can be done using simple logic or Java’s built-in methods for better efficiency and readability.

Can be performed using loops (manual sorting)
Provides built-in methods like Arrays.sort() and Collections.sort()
Works with arrays, lists, and other data structures

Ways of sorting in Java

1. Using loops

Java

 class GFG {

    // Main driver method
    public static void main(String[] args)
    {

        // Custom input array
        int arr[] = { 4, 3, 2, 1 };

        // Outer loop
        for (int i = 0; i < arr.length; i++) {

            // Inner nested loop pointing 1 index ahead
            for (int j = i + 1; j < arr.length; j++) {

                // Checking elements
                int temp = 0;
                if (arr[j] < arr[i]) {

                    // Swapping
                    temp = arr[i];
                    arr[i] = arr[j];
                    arr[j] = temp;
                }
            }

            // Printing sorted array elements
            System.out.print(arr[i] + " ");
        }
    }
}

Output

1 2 3 4

2. Using sort() method of Arrays class

Arrays.sort() works for arrays which can be of primitive data type also which in turn by default sorts in ascending order.

Example 1

JAVA

import java.util.Arrays;

public class GFG {

    public static void main(String[] args)
    {
        // Custom input array
        int[] arr = { 13, 7, 6, 45, 21, 9, 101, 102 };

        // Calling the sort() method present
        // inside Arrays class
        Arrays.sort(arr);

        // Printing and display sorted array
        System.out.printf("Modified arr[] : %s",
                          Arrays.toString(arr));
    }
}

Output

Modified arr[] : [6, 7, 9, 13, 21, 45, 101, 102]

Example 2: A sample Java program to sort an array in descending order using Arrays.sort().

JAVA

import java.util.Arrays;
import java.util.Collections;

public class GFG {
    public static void main(String[] args)
    {
        // Note that we have Integer here instead of
        // int[] as Collections.reverseOrder doesn't
        // work for primitive types.
        Integer[] arr = { 13, 7, 6, 45, 21, 9, 2, 100 };

        // Sorts arr[] in descending order
        Arrays.sort(arr, Collections.reverseOrder());

        System.out.printf("Modified arr[] : %s",
                          Arrays.toString(arr));
    }
}

Output

Modified arr[] : [100, 45, 21, 13, 9, 7, 6, 2]

3. Using sort() method of Collections class

Collections.sort() works for objects Collections like ArrayList and LinkedList.

Example 1

JAVA

import java.util.*;

public class GFG {
    public static void main(String[] args)
    {
        // Create a list of strings
        ArrayList<String> al = new ArrayList<String>();
        al.add("Geeks For Geeks");
        al.add("Friends");
        al.add("Dear");
        al.add("Is");
        al.add("Superb");

        /* Collections.sort method is sorting the
        elements of ArrayList in ascending order. */
        Collections.sort(al);

        // Let us print the sorted list
        System.out.println("List after the use of"
                           + " Collection.sort() :\n" + al);
    }
}

Output

List after the use of Collection.sort() :
[Dear, Friends, Geeks For Geeks, Is, Superb]

Example 2

JAVA

import java.util.*;

public class GFG {
    public static void main(String[] args)
    {
        // Create a list of strings
        ArrayList<String> al = new ArrayList<String>();
        al.add("Geeks For Geeks");
        al.add("Friends");
        al.add("Dear");
        al.add("Is");
        al.add("Superb");

        /* Collections.sort method is sorting the
        elements of ArrayList in ascending order. */
        Collections.sort(al, Collections.reverseOrder());

        // Let us print the sorted list
        System.out.println("List after the use of"
                           + " Collection.sort() :\n" + al);
    }
}

Output

List after the use of Collection.sort() :
[Superb, Is, Geeks For Geeks, Friends, Dear]

4. Sorting only a subarray

JAVA

import java.util.Arrays;

public class GFG {

    public static void main(String[] args)
    {
        // Custom input array
        int[] arr = { 13, 7, 6, 45, 21, 9, 2, 100 };

        // Sort subarray from index 1 to 4, i.e.,
        // only sort subarray {7, 6, 45, 21} and
        // keep other elements as it is.
        Arrays.sort(arr, 1, 5);

        // Printing sorted array
        System.out.printf("Modified arr[] : %s",
                          Arrays.toString(arr));
    }
}

Output

Modified arr[] : [13, 6, 7, 21, 45, 9, 2, 100]

Note:

Java’s sort() uses Dual-Pivot QuickSort for primitives and TimSort for objects, and by default sorts in ascending order.
Descending order can be achieved using Collections.reverseOrder(), while custom sorting can be implemented using algorithms like Quick Sort, Merge Sort, etc.

Sorting in Java

Ways of sorting in Java

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