Valid Anagram

import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;

import java.util.Arrays;

public class ValidAnagram {

    @Test
    public void test() {
        String s = "anagram";
        String t = "nagaram";
        Assertions.assertTrue(isAnagram(s, t));
        Assertions.assertTrue(isAnagramWithKey(s, t));

        String a = "rat";
        String b = "cat";
        Assertions.assertFalse(isAnagram(a, b));
        Assertions.assertFalse(isAnagramWithKey(a, b));

    }

    public boolean isAnagram(String s, String t) {
        int[] array = new int[128];
        for (char c : s.toCharArray()) {
            array[c]++;
        }
        for (char c : t.toCharArray()) {
            array[c]--;
        }
        for (int a : array) {
            if (a != 0) {
                return false;
            }
        }
        return true;
    }

    public boolean isAnagramWithKey(String s, String t) {
        return key(s).equals(key(t));
    }

    public String key(String s) {
        int[] array = new int[128];
        for (char c : s.toCharArray()) {
            array[c]++;
        }
        return Arrays.toString(array);
    }
}