Sort a List of strings in Java

This post will discuss how to sort a list of strings in lexicographical order in Java.

1. Using `Collections.sort()` method

A simple solution to in-place sort a list of strings in lexicographical order is using the Collections.sort() method. It takes a modifiable list, which need not be resizable.

import java.util.Arrays;

import java.util.Collections;

import java.util.List;

class Main

{

public static void main(String[] args)

{

List<String> faang = Arrays.asList("Facebook", "Amazon", "Apple",

"Netflix", "Google");

Collections.sort(faang);

System.out.println(faang);

}

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Output:

[Amazon, Apple, Facebook, Google, Netflix]

The Collections.sort() method optionally takes a comparator to allow precise control over the sort order. To make the comparison between two strings case-insensitive, you can use the String.CASE_INSENSITIVE_ORDER comparator.

import java.util.Arrays;

import java.util.Collections;

import java.util.List;

class Main

{

public static void main(String[] args)

{

List<String> faang = Arrays.asList("Facebook", "Amazon", "Apple",

"Netflix", "Google");

Collections.sort(faang, String.CASE_INSENSITIVE_ORDER);

System.out.println(faang);

}

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Output:

[Amazon, APPLE, Facebook, GOOGLE, Netflix]

2. Using `List.sort()` method

Another alternative to in-place sort a list of strings is with the List.sort() method, which was added to the specification in JDK 1.8. The Collections.sort() method is a wrapper over the List.sort() method. Hence, the above code is equivalent to:

import java.util.Arrays;

import java.util.List;

class Main

{

public static void main(String[] args)

{

List<String> faang = Arrays.asList("Facebook", "Amazon", "Apple",

"Netflix", "Google");

faang.sort(null);

System.out.println(faang);

}

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Output:

[Amazon, Apple, Facebook, Google, Netflix]

You can use the String.CASE_INSENSITIVE_ORDER comparator to make the sort operation compare strings by ignoring their order.

import java.util.Arrays;

import java.util.List;

class Main

{

public static void main(String[] args)

{

List<String> faang = Arrays.asList("Facebook", "Amazon", "Apple",

"Netflix", "Google");

faang.sort(String.CASE_INSENSITIVE_ORDER);

System.out.println(faang);

}

Download Run Code

Output:

[Amazon, APPLE, Facebook, GOOGLE, Netflix]

3. Using `Stream.sorted()` method

To create a sorted copy of the list, you can use Java 8 Stream. The idea is to create a sequential Stream over the elements in the list, sort the stream using the sorted() method, and collect all the sorted elements into a new List. This is demonstrated below:

import java.util.Arrays;

import java.util.List;

import java.util.stream.Collectors;

class Main

{

public static void main(String[] args)

{

List<String> faang = Arrays.asList("Facebook", "Amazon", "Apple",

"Netflix", "Google");

List<String> sorted_list = faang.stream().sorted().collect(Collectors.toList());

System.out.println(sorted_list);

}

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Output:

[Amazon, Apple, Facebook, Google, Netflix]

4. Using Guava

If you happen to use the Guava library in your project, you may want to explore the Ordering class. It offers the sortedCopy() method that returns a mutable list containing elements sorted by this ordering.

import com.google.common.collect.Ordering;

import java.util.Arrays;

import java.util.List;

class Main

{

public static void main(String[] args)

{

List<String> faang = Arrays.asList("Facebook", "Amazon", "Apple",

"Netflix", "Google");

List<String> sorted_list = Ordering.natural().sortedCopy(faang);

System.out.println(sorted_list);

}

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Output:

[Amazon, Apple, Facebook, Google, Netflix]

5. Using `TreeSet`

In a TreeSet, elements are ordered using their natural ordering or by provided Comparator. If your list contains distinct elements, you can insert all its elements into a TreeSet to get a sorted collection.

import java.util.ArrayList;

import java.util.Arrays;

import java.util.List;

import java.util.TreeSet;

class Main

{

public static void main(String[] args)

{

List<String> faang = Arrays.asList("Facebook", "Amazon", "Apple",

"Netflix", "Google");

List<String> sorted_list = new ArrayList<>(new TreeSet<>(faang));

System.out.println(sorted_list);

}

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Output:

[Amazon, Apple, Facebook, Google, Netflix]

That’s all about sorting a List of strings in Java.

Sort a List of strings in Java

1. Using Collections.sort() method

2. Using List.sort() method

3. Using Stream.sorted() method

4. Using Guava

5. Using TreeSet

Share this:

1. Using `Collections.sort()` method

2. Using `List.sort()` method

3. Using `Stream.sorted()` method

5. Using `TreeSet`