Create a class `AnagramChecker` that provides a method to check if two strings are anagrams. An anagram is a word or phrase formed by rearranging the letters of a different word or phrase, typically using all the original letters exactly once.
### Expected Class
```java
public class AnagramChecker {
public boolean isAnagram(String str1, String str2) {
// Implementation to check if str1 and str2 are anagrams