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如何使用带有三个参数的collect方法,即"collect(supplier,accumulator,combiner)“在列表中添加整数

collect(supplier, accumulator, combiner) 是Java 8中Stream API中的一个方法,用于将流中的元素收集到一个可变的结果容器中。

在使用 collect 方法时,需要提供三个参数:

  1. supplier:一个用于创建结果容器的 Supplier。它定义了如何创建一个空的容器对象,供 accumulator 和 combiner 方法使用。在这个问题中,我们需要使用 supplier 创建一个空的列表对象。
  2. accumulator:一个用于将流中的元素添加到结果容器的累加器函数。它接受两个参数:结果容器和流中的一个元素,并将该元素添加到容器中。在这个问题中,我们需要定义一个累加器函数来将整数添加到列表中。
  3. combiner:一个用于合并两个结果容器的组合器函数。它接受两个结果容器,并将它们合并为一个容器。在这个问题中,我们不需要使用 combiner 函数,因为我们不涉及并行处理。

下面是一个示例代码,演示如何使用 collect 方法来添加整数到列表中:

代码语言:txt
复制
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;

public class Main {
    public static void main(String[] args) {
        List<Integer> numbers = Stream.of(1, 2, 3, 4, 5)
                .collect(ArrayList::new, List::add, List::addAll);
        System.out.println(numbers);
    }
}

在上面的代码中,我们创建了一个包含整数 1 到 5 的流。然后使用 collect 方法,传入一个空的 ArrayList 作为 supplier,使用 List 的 add 方法作为 accumulator,将流中的整数一个个添加到列表中。最终,我们得到了一个包含整数 1 到 5 的列表。

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