Prevents Raw Throwables and NPE Code should never throw NPE under normal circumstances. A catch block may hide the original error, causing other more subtle errors in its wake. 3 Avoid throwing a raw Throwable, Exception, or Error. Use a subclassed exception or error. 1 Avoid throwing a raw RuntimeException. Use a subclassed RuntimeException. 1 Avoid throwing a NullPointerException. Use IllegalArgumentException or IllegalStateException. 1