string contain problem

Art

public final class Art {
  
  private static void checkRange(String s1, String s2) {
    if(s1 == null || s2 == null)
      throw new NullPointerException("null");
    if(s1.length() == 0 || s2.length() == 0)
      throw new IllegalArgumentException("zero");
    if(s1.length < s2.length())
      throw new IllegalArgumentException("length error");
  }
  
  public boolean compare(String s1, String s2) {
    checkRange(s1, s2);
    
    for(int i = 0; i < s2.length(); i++) {
      int j;
      for(j = 0; (j < s1.length()) && (s1.charAt(j) != s2.charAt(i)); ++j)
        ;
      if(j == s1.length())
        return false;
    }
    
    return true;
  }
  
  public boolean compareTwo(String s1, String s2) {
    checkRange(s1, s2);
    
    int[] array = new int[26];
    
    for(int i = 0; i < s1.length(); i++) {
      ++array[s1.charAt(i) - 'A'];
    }
    for(int j = 0; j < s2.length(); j++) {
      if(array[s2.charAt(j) - 'A'] == 0)
        return false;
    }
    
    return true;
  }
  
  public boolean compareThree(String s1, String s2) {
    checkRange(s1, s2);
    
    int[] array = new int[26];
    
    int m = 0;
    for(int i = 0; i < s2.length(); i++) {
      if(array[s2.charAt(i) - 'A'] == 0) {
        array[s2.charAt(i) - 'A'] = 1;
        ++m;
      }
    }
    
    for(int j = 0; j < s1.length(); j++) {
      if(array[s1.charAt(j) - 'A'] == 1) {
        array[s1.charAt(j) - 'A'] = 0;
        --m;
      }
    }
    
    return m == 0;
  }
  
  //Maybe the best solution
  //the time complexity is O(m+n)
  //the space complexity is O(1)
  public boolean compareFour(String s1, String s2) {
    checkRange(s1, s2);
    
    int hash = 0;
    for(int i = 0; i < s1.length(); i++) {
      hash |= (1<<(s1.charAt(i) - 'A'))
    }
    
    for(int i = 0; i < s2.length(); i++) {
      if((hash & (s2.charAt(i) - 'A')) == 0) {
        return false;
      }
    }
    
    return true;
  }
}