Arrays.sort() in Java with Examples

Arrays.sort() is a built-in method in Java’s java.util package that provides an efficient and convenient way to sort arrays. This method uses the Dual-Pivot Quicksort algorithm for primitive types and TimSort for objects.

Arrays.sort() Key Points

  1. For Primitive Data Types:
    • Sorts the array in ascending order.
    • Time complexity: O(n log⁡n) on average.
  2. For Objects:
    • Sorts the array in natural order (defined by the compareTo method of the objects).
    • You can use a custom comparator to define the sorting logic.

Arrays.sort() Method Signature

  1. For Primitive Arrays:
    public static void sort(int[] a)
  2. For Object Arrays:
    public static <T> void sort(T[] a)
  3. With Custom Comparator:
    public static <T> void sort(T[] a, Comparator<? super T> c)

Arrays.sort() method Examples in Java

1. Sorting Primitive Arrays

Demonstrates sorting an integer array in ascending order.

package com.javacodepoint.sort;

import java.util.Arrays;

public class ArraySort1 {
	public static void main(String[] args) {
		int[] numbers = { 5, 1, 12, -5, 16 };

		System.out.println("Original Array:");
		System.out.println(Arrays.toString(numbers));

		// Sort the array
		Arrays.sort(numbers);

		System.out.println("Sorted Array:");
		System.out.println(Arrays.toString(numbers));
	}
}

OUTPUT:

Original Array:
[5, 1, 12, -5, 16]
Sorted Array:
[-5, 1, 5, 12, 16]

2. Sorting Object Arrays (Strings)

It shows how to sort an array of strings alphabetically.

package com.javacodepoint.sort;

import java.util.Arrays;

public class ArraySort2 {
	public static void main(String[] args) {
        String[] names = {"John", "Alice", "Bob", "Diana"};

        System.out.println("Original Array:");
        System.out.println(Arrays.toString(names));

        // Sort the array
        Arrays.sort(names);

        System.out.println("Sorted Array:");
        System.out.println(Arrays.toString(names));
    }
}

OUTPUT:

Original Array:
[John, Alice, Bob, Diana]
Sorted Array:
[Alice, Bob, Diana, John]

3. Sorting with a Custom Comparator

Explains sorting an array in reverse order using a custom comparator.

package com.javacodepoint.sort;

import java.util.Arrays;
import java.util.Comparator;

public class ArraySort3 {
	public static void main(String[] args) {
		String[] names = { "John", "Alice", "Bob", "Diana" };

		System.out.println("Original Array:");
		System.out.println(Arrays.toString(names));

		// Sort the array in reverse order
		Arrays.sort(names, Comparator.reverseOrder());

		System.out.println("Sorted Array (Reverse Order):");
		System.out.println(Arrays.toString(names));
	}
}

OUTPUT:

Original Array:
[John, Alice, Bob, Diana]
Sorted Array (Reverse Order):
[John, Diana, Bob, Alice]

4. Sorting Part of an Array

Illustrates sorting a specific portion of an array using start and end indices.

package com.javacodepoint.sort;

import java.util.Arrays;

public class ArraySort4 {
	public static void main(String[] args) {
		int[] numbers = { 10, 5, 8, 20, 15 };

		System.out.println("Original Array:");
		System.out.println(Arrays.toString(numbers));

		// Sort part of the array (index 1 to 4, exclusive of 4)
		Arrays.sort(numbers, 1, 4);

		System.out.println("Partially Sorted Array:");
		System.out.println(Arrays.toString(numbers));
	}
}

OUTPUT:

Original Array:
[10, 5, 8, 20, 15]
Partially Sorted Array:
[10, 5, 8, 20, 15]

5. Sorting Custom Objects

This example demonstrates how to sort an array of custom objects, such as Student objects, based on a specific property (e.g., age). Since custom objects do not have a natural ordering, we use a custom comparator to define the sorting logic.

Sorting Logic: A lambda expression or a comparator is used to specify the criteria for sorting. For example, sorting by age uses: (s1, s2) -> Integer.compare(s1.age, s2.age)

package com.javacodepoint.sort;

import java.util.Arrays;

class Student {
	String name;
	int age;

	public Student(String name, int age) {
		this.name = name;
		this.age = age;
	}

	@Override
	public String toString() {
		return name + " (" + age + ")";
	}
}

public class ArraySort5 {
	public static void main(String[] args) {
		Student[] students = { 
				new Student("Alice", 22), 
				new Student("Bob", 20), 
				new Student("Charlie", 23) 
			};

		System.out.println("Original Array:");
		System.out.println(Arrays.toString(students));

		// Sort by age
		Arrays.sort(students, (s1, s2) -> Integer.compare(s1.age, s2.age));

		System.out.println("Sorted by Age:");
		System.out.println(Arrays.toString(students));
	}
}

OUTPUT:

Original Array:
[Alice (22), Bob (20), Charlie (23)]
Sorted by Age:
[Bob (20), Alice (22), Charlie (23)]

Java logical programs list

Java Basic Programs

  1. Java Hello world program
  2. Java Program to Add two Numbers
  3. Java Program to Subtract two Numbers
  4. Java Program to Multiply two Numbers
  5. Java Program to Check Whether a Number is Even or Odd.
  6. Check whether a character is a Vowel or Consonant.
  7. Java Program to find Average of Two Numbers
  8. Java Program to find Average of Three Numbers
  9. Java Program to find the Area of Square
  10. Java Program to Calculate Simple Interest
  11. Java Program to Calculate Compound Interest
  12. List of basic logical programs in Java
  13. How to print a Fibonacci series up to a given number in Java?
  14. How to calculate the factorial of a given number in java?
  15. How to check whether an integer number is a prime number or not in java?
  16. How to check whether a number is a perfect number or not in java?
  17. How to check whether a number is an Armstrong number or not in java?
  18. How to reverse a number in Java?
  19. How to check whether a number is a Palindrome number or not in Java?
  20. How to swap two numbers without using a third variable in Java?
  21. How to reverse a string without using the reverse() method in java?
  22. How to check whether a String is a Palindrome or not in java?
  23. How to count characters from the string in java?
  24. How to check if two strings are anagrams of each other?
  25. How to count the occurrence of the given character in a string in java?
  26. How to swap two strings without using the third variable in java?
  27. Searching Algorithms in Java with Examples

Java String Programs

  1. String length without using length() method.
  2. Count the Number of Vowels in a String.
  3. Swap two strings without using the third variable.
  4. Reverse a string without using the reverse() method.
  5. Reverse the words in a given string sentence
  6. Check whether a String is a Palindrome or not in Java.
  7. Count characters from the string in Java.
  8. Count the number of words in the String.
  9. Check if the two strings are anagrams of each other.
  10. Count the occurrence of the given character in a string.
  11. Find the Maximum Occurring Character in a String
  12. Find the First non-repeating Character in a given String
  13. Remove all Duplicates from a given String
  14. Remove a given character from the String
  15. Find the Sum of Digits in a String.
  16. Compare two Strings in Java.
  17. String Permutations Program in Java
  18. Combinations of String in Java

Java Pattern Printing Programs

  1. Star pattern programs [Tricks] in Java
  2. Top 30-star pattern programs in java
  3. Top 10 Number pattern programs in java
  4. Top 10 Character pattern programs in java
  5. Top 50 Pattern printing programs in java
  6. Pyramid Pattern.
  7. Diamond Pattern.
  8. Hollow Diamond Pattern.

Java Series Printing Programs

  1. Print a Fibonacci series
  2. Even Numbers Series
  3. Odd Numbers Series
  4. Square Numbers Series
  5. Cube Numbers Series
  6. Print Series 1,2,9,28,65
  7. Java Program to Print Series 1,2,5,10,17
  8. Java Program to Print Series 2,4,8,16,32

Java Array-Based Programs

  1. Find the Length of an Array
  2. Get Array Input
  3. Different Ways to Print an Array
  4. Print all Negative Elements in an Array.
  5. Find GCD of N Numbers
  6. Copy an Array
  7. Merge Two Arrays.
  8. Sum of Two Arrays.
  9. Print Odd/Even No. from an Array.
  10. Put Even and Odd Elements in 2 Separate Arrays
  11. Find the Sum of an Array
  12. Sum of Even Numbers in an Array.
  13. Average of Odd/Even Numbers in Array.
  14. Count Even and Odd numbers in Array
  15. Calculate Average Using Array
  16. Find the Smallest Number in an Array.
  17. Find the Largest Number in an Array.
  18. 2nd Largest Number in an Array.
  19. Remove duplicate elements in an Array.
  20. Remove odd numbers from an array Java.
  21. Add Element to Array in Java.
  22. Insert Element at Specific Position
  23. Remove Element From Array in Java
  24. Count Repeated Elements in an Array
  25. Compare Two Arrays in Java
  26. Reverse an Array in Java
  27. Searching in Java with Examples

Multi-Dimensional Array Programs

  1. Print Matrix or 2D Array.
  2. Read a Matrix from the User.
  3. Add the Two Matrices.
  4. Subtract the Two Matrices.
  5. Matrix Multiplication.
  6. Identity Matrix Program.
  7. Symmetric Matrix Program.
  8. Find the Transpose of a Matrix.
  9. Find the Smallest Element in a Matrix.
  10. Find the Largest Element in a Matrix.
  11. Search Matrix in Java.
  12. The sum of Diagonals of a Matrix.

Java Sorting Programs

  1. Selection Sort in Java
  2. Bubble Sort in Java
  3. Insertion Sort in Java
  4. Merge Sort in Java
  5. Quick Sort in Java
  6. Heap Sort in Java
  7. Arrays.sort() in Java with Examples
  8. Collections.sort() in Java with Examples

Java Searching Programs

  1. Linear Search in Java with Examples
  2. Binary Search in Java with Examples
  3. Fibonacci Search in Java with Examples
  4. Interpolation Search in Java Examples
  5. Exponential Search in Java Examples
  6. Jump Search in Java with Examples
  7. Ternary Search in Java with Examples

Java Conversion Programs

  1. Binary to Decimal
  2. Binary to Decimal using Recursion
  3. Decimal to Binary
  4. Decimal to Octal
  5. Decimal to Hexadecimal
  6. Fahrenheit to Celsius
  7. Celsius to Fahrenheit

Java Game Programs

  1. Tic-Tac-Toe Game in Java
  2. Hangman Game in Java
  3. Rock Paper Scissors Game in Java
  4. Number Guessing Game in Java
  5. Word Search Solver Game in Java
  6. Tower of Hanoi Game in Java

Java Miscellaneous Programs

  1. Generate Random String in Java
  2. Generating Random Numbers in Java
  3. Generating OTP in Java
  4. Secret Message Program in Java

Java Programs based on the Collection Framework

  1. ArrayList Manipulation: add, remove Elements, find size
  2. Write a Java program to reverse a List without using the built-in Collections.reverse() method.
  3. Find duplicate elements in an ArrayList
  4. Implement a Java program to sort an ArrayList of integer numbers.
  5. Implement a Java program to sort an ArrayList of custom objects based on a specific attribute.
  6. Create a stack using an ArrayList and implement push, pop, and peek operations.
  7. Convert an ArrayList of strings into a string array.
  8. Write a Java program to remove all elements from an ArrayList that are greater than a certain value.
  9. Write a Java program to remove duplicates from an ArrayList while preserving the original order.
  10. Write a Java program to find the common elements in two given ArrayLists.
  11. ArrayList partition into two separate lists of odd/even numbers.
  12. Write a program that extracts a sublist from an ArrayList, given a start and end index.
  13. Merge two sorted ArrayLists into a single sorted ArrayList.
  14. Find unique string in ArrayList with its frequency
  15. Write a program to swap the positions of two elements in an ArrayList given their indices.
  16. Write a program to Create a Custom LinkedList in Java
  17. Write a Java program for Basic Queue Implementation using LinkedList
  18. Write a Java program to create a PriorityQueue to manage a to-do list

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