Java List 类型转换

java的类型转换让人忍不住在开始编码前骂一声 FUCK!

1 子类转父类 up

List<SubClass> subs = ...;

List<? extends BaseClass> bases = subs;

2 父类转子类 down

//强转
public class TestA {}

public class TestB extends TestA{}

List<TestB> variable = (List<TestB>)(List<?>) collectionOfListA;

3 stream方式

collection.stream()

    .filter(obj -> obj instanceof ScheduleIntervalContainer)

    .map(obj -> (ScheduleIntervalContainer) obj)

参考:

巴特西