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Sort Words in a String in Java

beginner· Strings · String Manipulation

Problem

Sorting a sentence's words means rearranging the words themselves into alphabetical order, while each word's own letters stay exactly as they were.

Given a sentence, arrange its words in alphabetical order.

Input

banana apple cherry

Output

apple banana cherry

Java Program

Java

import java.util.Arrays;

public class SortWords {
    public static void main(String[] args) {
        String str = "banana apple cherry";
        String[] words = str.split(" "); // break the sentence into individual words
        Arrays.sort(words); // sorts the array in place, using each word's natural (dictionary) order
        System.out.println(String.join(" ", words)); // stitches the sorted words back into a sentence
    }
}

▶ Run Code

Output

apple banana cherry

Core Logic

Splitting the sentence into an array of words, sorting that array, and joining it back together reorders the words alphabetically.

How It Works

1str.split(" ") breaks the sentence into an array of individual words.
2Arrays.sort(words) sorts the array of Strings in place, using each word's natural (dictionary) ordering.
3String.join(" ", words) stitches the now-sorted words back into a single sentence, with single spaces between them.

For "banana apple cherry", the array ["banana", "apple", "cherry"] sorts to ["apple", "banana", "cherry"], producing "apple banana cherry".

💡

Key Point: Arrays.sort() on an array of Strings compares them lexicographically — the same character-by-character comparison String.compareTo() uses, not by word length.

Complexity

Time Complexity: O(n log n)Space Complexity: O(n)

Why: split() allocates an array of words, and sorting that array costs O(n log n) comparisons, where each comparison itself scans the words being compared.

Key Concepts

String.split()Arrays.sort()String.join()

Approach 2: Java 8

Java

import java.util.Arrays;
import java.util.stream.Collectors;

public class SortWordsStream {
    public static void main(String[] args) {
        String str = "banana apple cherry";
        // sorted() sorts the words; Collectors.joining() rejoins them into a sentence
        String result = Arrays.stream(str.split(" "))
            .sorted()
            .collect(Collectors.joining(" "));
        System.out.println(result);
    }
}

▶ Run Code

Output

apple banana cherry

Core Logic

The same sort can be expressed as a stream pipeline — sort the stream of words directly, then join them back into a sentence.

How It Works

1Arrays.stream(str.split(" ")) turns the split words into a Stream<String>.
2.sorted() sorts the stream using each word's natural ordering, the stream equivalent of Arrays.sort().
3.collect(Collectors.joining(" ")) joins the sorted words back together with single spaces between them.

Sorting ["banana", "apple", "cherry"] and joining the result produces the same sentence as the array version: "apple banana cherry".

💡

Key Point: This does the same O(n log n) sort as the array version, just expressed as a stream pipeline instead of a mutation-in-place call.

Complexity

Time Complexity: O(n log n)Space Complexity: O(n)

Why: sorted() still performs the same comparison sort over the words, and Collectors.joining() builds a result string holding the whole sentence.

Key Concepts

StreamArrays.stream()sorted()Collectors.joining()

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