Anagram Check Program in Java

What is an anagram

Two words are anagrams if they use exactly the same letters, just in a different order — like listen and silent. Checking for anagrams in Java is a classic string exercise, and there are two neat ways: sorting and counting characters.

The sorting method

import java.util.Arrays;

String a = "listen", b = "silent";
char[] x = a.toCharArray();
char[] y = b.toCharArray();
Arrays.sort(x);
Arrays.sort(y);
System.out.println(Arrays.equals(x, y));

We turn each string into a char array, sort both, and compare. If they are anagrams, sorting makes them identical — Arrays.equals then returns true.

Dry run

The counting method

String a = "listen", b = "silent";
if (a.length() != b.length()) {
    System.out.println("Not anagram");
} else {
    int[] count = new int[26];
    for (char c : a.toCharArray()) count[c - 'a']++;
    for (char c : b.toCharArray()) count[c - 'a']--;
    boolean anagram = true;
    for (int n : count) if (n != 0) anagram = false;
    System.out.println(anagram);
}

We add up letters from the first word and subtract those from the second. If every count ends at 0, both words used the same letters — they are anagrams. This avoids sorting.

Cleaning the input

For real checks, ignore case and spaces first:

a = a.toLowerCase().replaceAll("\\s", "");
b = b.toLowerCase().replaceAll("\\s", "");

This lets "Listen" and "Silent", or phrase anagrams like "conversation" and "voices rant on", compare correctly regardless of case and spacing.

Common mistakes

• Not checking lengths. Different lengths can never be anagrams — check first.
• Ignoring case and spaces. Lowercase and strip spaces for phrases.
• Comparing arrays with ==. Use Arrays.equals, not ==.
• Assuming only lowercase letters in counting. The c - 'a' trick assumes a-z only.

Summary

• Anagrams use the same letters in a different order.
• Sorting method: sort both char arrays and compare with Arrays.equals.
• Counting method: add letters from one, subtract from the other, check all zeros.
• Lowercase and remove spaces for phrase anagrams.
• Different lengths mean not anagrams.

Next, reverse text in reverse a string, or sort with bubble sort.