code: public static boolean isEquals( String s1, String s2)
  	{
  		return s1 == null ? s2 == null : s1.equals(s2);
  	}
docs: <p>isEquals.</p>
  
  @param s1 a {@link java.lang.String} object.
  @param s2 a {@link java.lang.String} object.
  @return a boolean.