code: public static boolean contains(String str, String searchStr) {
        if (str == null || searchStr == null) {
            return false;
        }
        return str.indexOf(searchStr) >= 0;
    }
docs: <p>Checks if String contains a search String, handling <code>null</code>.
  This method uses {@link String#indexOf(String)}.</p>
  
  <p>A <code>null</code> String will return <code>false</code>.</p>
  
  <pre>
  GosuStringUtil.contains(null, *)     = false
  GosuStringUtil.contains(*, null)     = false
  GosuStringUtil.contains("", "")      = true
  GosuStringUtil.contains("abc", "")   = true
  GosuStringUtil.contains("abc", "a")  = true
  GosuStringUtil.contains("abc", "z")  = false
  </pre>
  
  @param str  the String to check, may be null
  @param searchStr  the String to find, may be null
  @return true if the String contains the search String,
  false if not or <code>null</code> string input
  @since 2.0