Stream.Foreach中的多行代码

Question

String fileName = "dataset/ANC-all-count.txt";
Integer i=0;
//read file into stream, try-with-resources
try (Stream<String> stream = Files.lines(Paths.get(fileName), StandardCharsets.ISO_8859_1)) {

    stream.forEach(System.out::println);
    i++;

} catch (IOException e) {
    e.printStackTrace();
}
System.out.println("count is : "+i);

stream.forEach(System.out::println);

stream.forEach(System.out::println; i++);

Answer 1

在这里你应该问两件完全不同的事情：

a)如何在stream.foreach()中放置多行代码？

b)如何计算流中的行数？

class Counter { // wrapper class
    private int count;
    public int getCount() { return count; }
    public void increaseCount() { count++; }
}

后来呢

Counter counter = new Counter();
lines.stream().forEach( e -> {
    System.out.println(e);
    counter.increaseCounter(); // or i++; if you decided i is worth being a field
} );

另一种方法是在方法中隐藏多行：

class Counter { // wrapper class
    private int count;
    public int getCount() { return count; }
    public void increaseCount( Object o ) {
        System.out.println(o);
        count++;
    }
}

后来呢

Counter counter = new Counter();
lines.stream().forEach( counter::increaseCount );

Counter counter = new Counter();
lines.stream().forEach( e -> counter.increaseCount(e) );