如何在Java8中过滤列表？

Question

I'm used to C# and the lambda expressions, but i couldn't filter a java list based on certain criterias.

Ex:

List<MyObject> list;

I need to get all the MyObject that have a isMyFlag() true.

In C# is really easy using IEnumerable... Is there any similar to IEnumerable in Java?

Answer 1

See the new Stream API in Java 8

You need to do a filter and then collect the results in a list using the Stream API:

list.stream().filter(x -> x.isMyFlag()).collect(Collectors.toList());

Answer 2

With lambdas you could do the following:

List<MyObject> filteredList = list.stream().filter(myObj -> myObj.isMyFlag())
                                           .collect(Collectors.toList());

Answer 3

To use the Stream API you need to call the stream() method. This is perhaps a surprise coming from C# as you don't need to do this, but once you have got over that hurdle it should be much the same.

List<MyObject> list2 = list.stream()
                           .filter(m -> m.isMyFlag())
                           .collect(Collectors.toList());