When invoking unknown code ( which listeners certainly qualify as), it is prudent to execute it in a try-catch block so that ill-behaved listeners do not do more damage than necessary. 在调用未知代码(侦听器就是这样的代码)时,谨慎的方式是在try-catch块中执行它,这样,行为有误的侦听器不会造成更多不必要的破坏。