Menu
dirPath contains 200k files. I want to read them one by one and do some processing. The following snippet causes java.nio.file.FileSystemException: dirPath/file-N Too many open files. Isn't the terminal operation forEach() supposed to close the open stream (i.e. the open file) before moving to the next one? In other words, do I have to add try-with-resources for the streamed files?
Files.list(dirPath) .forEach(filePath -> { Files.lines(filePath).forEach() { ... } }); 
363
A terminal operation in Java is a method applied to a stream as the final step. 2. Return Type. They only return another stream. They return final result.
No. You cannot use a stream multiple times. What you can do is , you can collect the stream in a list and then you can call the map and forEach functions which accepts a lambda.
Avoiding the Use of the Reduce MethodA stream does not process any data if it does not end with a terminal operation. We already covered the terminal operation reduce() , and you saw several terminal operations in other examples. Let us now present the other terminal operations you can use on a stream.
The distinction between this operations is that an intermediate operation is lazy while a terminal operation is not. When you invoke an intermediate operation on a stream, the operation is not executed immediately. It is executed only when a terminal operation is invoked on that stream.
No forEach does not close the stream (created by Files.list or Files.lines). It is documented in the javadoc, for example for Files.list:
The returned stream encapsulates a Reader. If timely disposal of file system resources is required, the try-with-resources construct should be used to ensure that the stream's close method is invoked after the stream operations are completed.
112
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
