问题描述
几天前我意识到PrintWriter(以及PrintStream)永远不要在写入、刷新或关闭时抛出 IOException.
Some days ago I realized that PrintWriter (as well as PrintStream) never throw an IOException when writing, flushing or closing.
相反，它会在发生错误时设置一个内部标志 (trouble=true).
不可能得到确切的异常，但只有如果有一些异常(checkError()).
Instead it sets an internal flag (trouble=true) when an error occurs.
It's not possible to get the exact exception, but only if there was some exception (checkError()).
我的问题是:为什么会有这样的行为?这不是糟糕的 API 设计吗?
My question is: why would one want to have such behavior? Isn't that bad API design?
推荐答案
我认为因为 System.out 和 System.err 是 PrintStream，提供了一些更轻松的错误处理.正如其他海报所提到的，这可能是为了为大约 1995 年从 C/C++ 过渡的人铺平道路.当添加阅读器/编写器 API 时，创建了 PrintWriter 以与现有的 并行打印流.
I think that since System.out and System.err are instances of PrintStream, some more relaxed error handling was provided. This was probably, as other posters have mentioned, to smooth the way for those transitioning from C/C++ circa 1995. When the Reader/Writer API was added, PrintWriter was created to parallel the existing PrintStream.
这种行为非常需要的一个应用程序是日志记录.日志记录是大型应用程序的辅助工具.通常，如果日志记录失败，人们不希望整个应用程序失败.因此，System.err 至少可以忽略异常.
One application where this behavior is extremely desirable is logging. Logging is ancillary to a larger application. Typically, if logging fails, one doesn't want that the entire application to fail. Thus, it makes sense for System.err, at least, to ignore exceptions.
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