String ---Valid Anagram

Given two strings s and t, write a function to determine if t is an anagram of s.

For example,

s = “anagram”, t = “nagaram”, return true.

s = “rat”, t = “car”, return false.

public class Solution {
public boolean isAnagram(String s, String t) {
if(s.length() != t.length()) return false;
int [] charSet = new int [256];
char [] source = s.toCharArray();
char [] target = t.toCharArray();
for (int i = 0; i < source.length; i++){
charSet[((int) source[i])]++;
}
for (int i = 0; i < target.length; i++){
charSet[((int) target[i])]--;
if (charSet[((int) target[i])] < 0) return false;

}
return true;
}
}