Anagram Check in Java: Solution, Explanation & Practice

Check if two strings are anagrams

Problem summary

Write a program that checks if two strings are anagrams (same characters, different order).

Starter code

public class Main {
    public static void main(String[] args) {
        String s1 = "listen";
        String s2 = "silent"; // Test case 1
        
        // Check if anagrams
        // Print: Are anagrams: <true/false>
    }
}

Expected output and test cases

listen/silent are anagrams
```
Are anagrams: true
```
triangle/integral
```
Are anagrams: true
```
hello/world not anagrams
```
Are anagrams: false
```

Hints

Sort both strings and compare
Or count character frequencies
Must have same length first

Validated solution

Reveal Java solution

import java.util.Arrays;

public class Main {
    static boolean areAnagrams(String first, String second) {
        char[] a = first.toLowerCase().toCharArray();
        char[] b = second.toLowerCase().toCharArray();
        Arrays.sort(a); Arrays.sort(b);
        return Arrays.equals(a, b);
    }
    public static void main(String[] args) {
        System.out.println("Are anagrams: " + areAnagrams("listen", "silent"));
    }
}

How to approach the problem

Two strings are anagrams when their normalized character multisets match. Sorting both character arrays creates a canonical order that Arrays.equals can compare directly.

Approach

Define normalization; this version ignores case only.
Convert to mutable char arrays.
Sort and compare the full arrays.

Time and space complexity

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

Edge cases to test

Different lengths can return false before sorting as an optimization.
Spaces and punctuation count in this version.

Common mistakes

Comparing the original strings after sorting copies.
Using == for content equality.

Follow-up challenge

Implement an O(n) frequency-count solution for lowercase a-z input.

Related Strings exercises

Practice all Strings exercises · Run this idea in the Java compiler