Read lines using Vert.x and RxJava

Question

I'm reading a property file using Vert.x File System API and would need to do some transformations on it. The problem is that the File is not being read line by line but as a single chunk. So, assuming I have this property file:

name=abc name=def

And using this code:

vertx.fileSystem().rxReadFile("/path/file.properties") .map(buffer -> buffer.toString()) .subscribe(data -> { System.out.println(">"+data); }, err -> System.out.println("Cannot read the file: " + err.getMessage()));

What I get printed is a single chunk of data:

>name=abc name=def

I'd expect the following, as I have to perform transformations on each line:

>name=abc >name=def

Gustavo Pagani · Accepted Answer · 2019-10-07 08:50:24Z

1

You can just replace this line:

.map(buffer -> buffer.toString())

By:

.flatMapObservable(buffer -> Observable.fromArray(buffer.toString().split("\n")))

The code above will split the buffer by line breaks and emit line by line to the stream.

edited Oct 7, 2019 at 8:50

answered Oct 6, 2019 at 19:12

Gustavo Pagani

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3 Comments

Carla Over a year ago

Thanks for your reply. I'd go with the first solution, however in that context "buffer" is undefined. By using .flatMap(buffer -> Observable.fromArray(buffer.toString().split("\n"))) does not compile either because it does not conform to a SingleSource

Carla Over a year ago

I've tried with the second solution too, but I don't have any .collect method available from vertx.fileSystem().rxReadFile

Gustavo Pagani Over a year ago

apologies, I thought vertx.fileSystem().rxReadFile was returning an Observable, but it returns a Single. I updated my answer

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