使用Java 8 Stream API收集列表列表

Question

I have the following line stream that I read from a file

1 2 4.5

1 6 3 5.5 5.3 6

1 7.2 5 7

How can I collect these lines in a single list of list considering only the Integers? (Notice that within each line the numbers are separated by one or more white spaces)

This is what I tried, but this give me one single list of all integer elements.

        list = reader.lines()
            .map(m -> m.split("\\n"))
            .flatMap(Arrays::stream)
            .map(m -> m.split("\\s+"))
            .flatMap(Arrays::stream)
            .filter(f -> !f.contains("."))
            .map(Integer::parseInt)
            .collect(Collectors.toList());

Answer 1

reader.lines()
   .map(line -> Arrays.stream(line.split("\\s+"))
                      .filter(f -> !f.contains("."))
                      .map(Integer::parseInt)
                      .collect(Collectors.toList())
   .collect(Collectors.toList())

Answer 2

This should do the trick.

list = reader.lines()
    .map(line -> Arrays.stream(line.split("\\s+"))
        .filter(number -> !number.contains("."))
        .map(Integer::parseInt)
        .collect(Collectors.toList()))
    .collect(Collectors.toList());

You may also want to filter for empty lines:

 list = reader.lines()
    .map(line -> Arrays.stream(line.split("\\s+"))
        .filter(number -> !number.contains("."))
        .map(Integer::parseInt)
        .collect(Collectors.toList()))
    .map(l -> !l.isEmpty())
    .collect(Collectors.toList());