PrintWriter and PrintStream's suffering------buffer problem

Because of the simplicity of printwriter, which requires only print () statements to output anything, there are a lot of times to use this class, but I often overlook the construction method: New PrintWriter (New FileOutputStream (), True);

If you don't add this true, the consequences are incredible ...

Not only in the operation of the file stream, but also in the network programming socket, the output stream of the socket will be wrapped through printwriter, if it is not added true, the output will not be obtained at the other end;

So the purpose of writing this article is to remember the buffer problem, although I have written a similar article before;