PrintWriter和PrintStream不会抛出IOExceptions [英] PrintWriter and PrintStream never throw IOExceptions

问题描述

几天前，我意识到 PrintWriter （以及 PrintStream ）在写入，刷新或关闭时不要抛出IOException 。

Some days ago I realized that PrintWriter (as well as PrintStream) never throw an IOException when writing, flushing or closing.

而是设置一个内部标志（ trouble = true ）发生错误。

不可能得到确切的异常，但只有如果有一些例外（ 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？不是那么糟糕的API设计？

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 的实例，提供了一些更放松的错误处理。正如其他海报所提到的那样，为了顺利地从C / C ++大约1995年过渡。当添加了Reader / Writer API时， PrintWriter 被创建为平行现有的 PrintStream 。

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.

这种行为是非常理想的一个应用程序是日志记录。日志记录是更大的应用程序的附件。通常，如果日志记录失败，则不希望整个应用程序失败。因此，至少要忽略例外， System.err 是有意义的。

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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