如何计算与Streams匹配谓词的元素数量？ [英] How can I count the number of elements that match a predicate with Streams?

问题描述

在Java7中我有这样的代码：

In Java7 I have this code:

public int getPlayersOnline() {
    int count = 0;
    for (Player player : players) {
        if (player.isActive()) {
            count++;
        }
    }
    return count;
}

我正在尝试尽可能多地使用Java 8功能，怎么能我用lambdas来改善这个？

I'm trying to use Java 8 features as much as possible, how can I go about improving this with lambdas?

推荐答案

这将是一个单行：

return (int) players.stream().filter(Player::isActive).count();

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