在一个可变列表中收集:

targetList = sourceList.stream()
                       .filter(i -> i > 100) //apply filter
                       .collect(Collectors.toList());

在一个不可变列表中收集:

targetList = sourceList.stream()
                       .filter(i -> i > 100) //apply filter
                       .collect(Collectors.toUnmodifiableList());

从JavaDoc中collect的解释:

Performs a mutable reduction operation on the elements of this stream using a Collector. A Collector encapsulates the functions used as arguments to collect(Supplier, BiConsumer, BiConsumer), allowing for reuse of collection strategies and composition of collect operations such as multiple-level grouping or partitioning. If the stream is parallel, and the Collector is concurrent, and either the stream is unordered or the collector is unordered, then a concurrent reduction will be performed (see Collector for details on concurrent reduction.) This is a terminal operation. When executed in parallel, multiple intermediate results may be instantiated, populated, and merged so as to maintain isolation of mutable data structures. Therefore, even when executed in parallel with non-thread-safe data structures (such as ArrayList), no additional synchronization is needed for a parallel reduction.

String joined = 
                Stream.of(isRead?"read":"", isFlagged?"flagged":"", isActionRequired?"action":"", isHide?"hide":"")
                      .filter(s -> s != null && !s.isEmpty())
                      .collect(Collectors.joining(","));

如果您有一个原语数组，您可以使用Eclipse collections中提供的原语集合。

LongList sourceLongList = LongLists.mutable.of(1L, 10L, 50L, 80L, 100L, 120L, 133L, 333L);
LongList targetLongList = sourceLongList.select(l -> l > 100);

如果你不能从List中更改sourceLongList:

List<Long> sourceLongList = Arrays.asList(1L, 10L, 50L, 80L, 100L, 120L, 133L, 333L);
List<Long> targetLongList = 
    ListAdapter.adapt(sourceLongList).select(l -> l > 100, new ArrayList<>());

如果您想使用LongStream:

long[] sourceLongs = new long[]{1L, 10L, 50L, 80L, 100L, 120L, 133L, 333L};
LongList targetList = 
    LongStream.of(sourceLongs)
    .filter(l -> l > 100)
    .collect(LongArrayList::new, LongArrayList::add, LongArrayList::addAll);

注意:我是Eclipse Collections的贡献者。

您所做的可能是最简单的方法，前提是您的流保持顺序—否则您将不得不在forEach之前调用sequential()。

[later edit: the reason the call to sequential() is necessary is that the code as it stands (forEach(targetLongList::add)) would be racy if the stream was parallel. Even then, it will not achieve the effect intended, as forEach is explicitly nondeterministic—even in a sequential stream the order of element processing is not guaranteed. You would have to use forEachOrdered to ensure correct ordering. The intention of the Stream API designers is that you will use collector in this situation, as below.]

另一种选择是

targetLongList = sourceLongList.stream()
    .filter(l -> l > 100)
    .collect(Collectors.toList());

更新:

另一种方法是使用collections . tolist:

targetLongList = 
    sourceLongList.stream().
    filter(l -> l > 100).
    collect(Collectors.toList());

之前的解决方案:

另一种方法是使用collections . tocollection:

targetLongList = 
    sourceLongList.stream().
    filter(l -> l > 100).
    collect(Collectors.toCollection(ArrayList::new));

如果有人(比如我)正在寻找处理对象而不是基本类型的方法，那么就使用mapToObj()

String ss = "An alternative way is to insert the following VM option before "
        + "the -vmargs option in the Eclipse shortcut properties(edit the "
        + "field Target inside the Shortcut tab):";

List<Character> ll = ss
                        .chars()
                        .mapToObj(c -> new Character((char) c))
                        .collect(Collectors.toList());

System.out.println("List type: " + ll.getClass());
System.out.println("Elem type: " + ll.get(0).getClass());
ll.stream().limit(50).forEach(System.out::print);

打印:

List type: class java.util.ArrayList
Elem type: class java.lang.Character
An alternative way is to insert the following VM o