How to Sort ArrayList of Strings Alphabetically in Java

How to Sort ArrayList of Strings Alphabetically in Java? In this section, we will discuss how to sort ArrayList of strings alphabetically in Java. Let us understand it through an example:-

For example:-
list = [“Java”, “Python”, “HTML”, “C++”, “CSS”]
list after sorting alphabetically:- [C++, CSS, HTML, Java, Python]

To sort ArrayList of strings alphabetically in Java we can take help of Collections class sort() method. When we call Collections.sort() method for ArrayList of strings then by default it will sort them in ascending order of alphabets i.e. in alphabetical order.

Program to Sort ArrayList of Strings Alphabetically in Java

Let us see how to sort strings alphabetically in Java. We will follow the following steps:-

Step1: First we will import the needed libraries that are ArrayList, Collections, and Iterator.
Step2: Create a main method in the main class and also create an ArrayList method and add elements to the list by using arrayList.add() and then use the sort() method in the collections framework to sort the array list of strings.
Step3: Display the output i.e. both the list before sorting and after sorting.

Program to Sort ArrayList of Strings Alphabetically in Java

import java.util.ArrayList;
import java.util.Collections;

public class Main {

   public static void main(String[] args) {
      ArrayList<String> names = new ArrayList<>();
      
      names.add("Zen");
      names.add("Fishley");
      names.add("John");
      names.add("Kernel");
      names.add("Manya");
      names.add("Lohith");
      names.add("Henry");
      names.add("Albert");
      names.add("Cubbon");
      names.add("Donald");
      System.out.println("ArrayList before sorting: " + names);

      Collections.sort(names);
      System.out.println("ArrayList after sorting: " + names);
   }
}

Output:-

ArrayList before sorting: [Zen, Fishley, John, Kernel, Manya, Lohith, Henry, Albert, Cubbon, Donald]
ArrayList after sorting: [Albert, Cubbon, Donald, Fishley, Henry, John, Kernel, Lohith, Manya, Zen]

Program to Sort ArrayList of Strings Alphabetically Reverse in Java

In the above program, we have seen how to sort ArrayList of strings alphabetically in Java. Now let us see how to sort ArrayList of strings in reverse alphabetical order.

To sort in reverse order we can take the help of the sort() and reverseOrder() method given in the Collections class. The reverseOrder() method returns a comparator which is passed to the sort() method as a second parameter.

import java.util.ArrayList;
import java.util.Collections;

public class Main {

   public static void main(String[] args) {
      ArrayList<String> names = new ArrayList<>();
      
      names.add("Zen");
      names.add("Fishley");
      names.add("John");
      names.add("Kernel");
      names.add("Manya");
      names.add("Lohith");
      names.add("Henry");
      names.add("Albert");
      names.add("Cubbon");
      names.add("Donald");
      System.out.println("ArrayList before sorting: " 
                         + names);

      Collections.sort(names, Collections.reverseOrder());
      System.out.println("ArrayList after sorting in "+
                         "reverse order: " + names);
   }
}

Output:-

ArrayList before sorting: [Zen, Fishley, John, Kernel, Manya, Lohith, Henry, Albert, Cubbon, Donald]
ArrayList after sorting in reverse order: [Zen, Manya, Lohith, Kernel, John, Henry, Fishley, Donald, Cubbon, Albert]

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