Observerable of file lines

package cvi6.demonstrations;

import io.reactivex.Observable;
import io.reactivex.ObservableEmitter;
import io.reactivex.ObservableOnSubscribe;

import java.io.BufferedReader;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

public class RxFileReader implements ObservableOnSubscribe<String> {

    protected Path filePath;

    public RxFileReader(Path filePath) {
        this.filePath = filePath;
    }

    public void subscribe(ObservableEmitter<String> emitter) {
        try {
            // prepare buffered reader for file
            BufferedReader br;
            br = Files.newBufferedReader(filePath);

            // read line by line
            String line = "";
            while((line = br.readLine()) != null) {
                // emit each line
                emitter.onNext(line);
            }
        } catch (IOException e) {
            // emit error
            emitter.onError(e);
        }
        // if all successful, emit on complete
        emitter.onComplete();
    }

    public static void main(String[] args) {
        RxFileReader reader = new RxFileReader(Paths.get("data.txt"));
        Observable.create(reader)
        .takeWhile(line -> !line.contains("=="))
        .forEach(System.out::println);

        System.out.println("==========");

        // this will open the file again and won't continue in reading
        Observable.create(reader)
        .takeWhile(line -> !line.contains("=="))
        .forEach(System.out::println);
    }
}