How do I iterate through the files in a directory in Java?

Question

I need to get a list of all the files in a directory, including files in all the sub-directories. What is the standard way to accomplish directory iteration with Java?

Answer 1

I like to use Optional and streams to have a net and clear solution, i use the below code to iterate over a directory. the below cases are handled by the code:

1. handle the case of empty directory
2. Laziness

but as mentioned by others, you still have to pay attention for outOfMemory in case you have huge folders

    File directoryFile = new File("put your path here");
    Stream files = Optional.ofNullable(directoryFile// directoryFile
                                                          .listFiles(File::isDirectory)) // filter only directories(change with null if you don't need to filter)
                                 .stream()
                                 .flatMap(Arrays::stream);// flatmap from Stream to Stream