you need to obtain a value from a dictionary, without having to handle an exception if the key you seek is not in the dictionary.
你需要从字典中获得一个值,不要处理在字典里找不到你所需要的键值的异常。
for example, an administrative staff could handle an exception in a task (for example, invalid order, system failure).
例如,管理员可能处理任务中的异常(例如,无效的命令、系统崩溃)。
you want to partially handle an exception before passing it on for additional handling.
所需部分处理异常之前将它传递进行额外处理。
if a service thread does not handle an exception due to programming error, it will kill the whole application.
如果服务线程因编程错误而没有处理某个异常,则会造成整个应用程序崩溃。