Close Java 8 Stream

Question

If we use Java 8 Stream like list.stream().filter(....).collect(..)..... When is it closed this stream?

Is it good practice that we close the stream us as the next example?

Stream<String> stream = list.stream(); String result = stream.limit(10).collect(Collectors.joining("")); stream.close(); 

Answer 1

It is generally not necessary to close streams at all. You only need to close streams that use IO resources.

From the Stream documentation:

Streams have a BaseStream.close() method and implement AutoCloseable, but nearly all stream instances do not actually need to be closed after use. Generally, only streams whose source is an IO channel (such as those returned by Files.lines(Path, Charset)) will require closing. Most streams are backed by collections, arrays, or generating functions, which require no special resource management. (If a stream does require closing, it can be declared as a resource in a try-with-resources statement.)

If you need to close a stream, then best practice would be to use the try-with-resources statement:

try ( Stream<String> stream = Files.lines(path, charset) ) {     // do something }