Anagram.java

package kata.string;

import java.util.Map;
import java.util.HashMap;

public class Anagram {

    private static Map<Character, Integer> toMap(String str) {
        Map<Character, Integer> map = new HashMap<>();

        for (int i = 0; i < str.length(); i++) {
            Character character = str.charAt(i);
            if (map.containsKey(character)) {
                Integer count = map.get(character);
                map.put(character, count++);
            }
            else {
                map.put(character, 1);
            }
        }
        return map;
    }

    public static boolean isAnagram(String str1, String str2) {
        if (str1 == null || str2 == null) { return false; }

        boolean result = false;

        Map<Character, Integer> map1 = toMap(str1);
        Map<Character, Integer> map2 = toMap(str2);

        for (Map.Entry<Character, Integer> entry : map1.entrySet()) {

            Integer count1 = entry.getValue();
            Integer count2 = map2.get(entry.getKey());

            if (count2 == null || count1 != count2) {
                return false;
            }
        }

        return true;
    }

}