试试这个：

AtomicLong count = new AtomicLong();
lines.stream().forEach(line -> {
    count.getAndIncrement();
    // do something with line;
});

如果我没听错的话，你就得算你的羔羊。当然，你能做到。只是初始化一个 count 在执行 forEach 并增加 count 在你的lambda街区。这样地：

final BufferedReader inReader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"));
// fixed the long by this
final AtomicLong counter = new AtomicLong();
inReader.lines().forEach(line -> {
  counter.incrementAndGet();
  // do something with the line
});
// here you can do something with the count variable, like printing it out
System.out.printf("count=%d%n", counter.get());

这个 forEach 方法来自 Iterable . 这绝对不是我选择的处理读者的方式。我会这样做：

try (BufferedReader inReader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"))) {
  Stream<String> lines = inReader.lines();
  long i = lines.peek(line -> {
        // do something with the line
     }).count();
  System.out.printf("count=%d%n", i);

}
附言：没有真正测试这个，所以纠正我，如果我做错了。