Book/Effective Java (5) 썸네일형 리스트형 [Effective Java] Item 45: Use streams judiciously 1 Creating streams Before I started this topic, there were some preliminaries that I had to be familiar with. You know those times when you try to get a stream of SomeType, but instead you get a stream of List instead? The following examples will clarify them: 1.1 int[] array stream Arrays.stream(int[]) - returns IntStream Arrays.stream(Integer[]) - returns Stream Stream.of(int...) - returns Str.. [Effective Java] Item 43: Prefer method reference to lambda Motivation Method reference is something I always tried to get into. However, always felt a little bit too overwhelming for me when I tried to get into it, because unlike lambda (which also took a great deal to get used to), method reference comes in different flavours (static method reference, instance method reference..) I am now a tiny bit confident that I understand about method reference. S.. [Effective Java] Item 42: Prefer lambda to anonymous classes In the previous post (Item 38: emulate extensible enums with interfaces), we had an enum declaration that implements different behaviour of overriden method for each enum instance. Just to refresh memory, here's what we had: An advantage of this is extreme flexibility - GradeCalculable interface's abstract method is implemented all differently for each enum instance. However, the fallpit of this.. [Effective Java] Item 38: emulate extensible enums with interfaces Enums cannot be extended. What does that mean? If we have an enum, and it had a method, then we cannot create another enum that implements the same method signature while being under the same type. There's a workaround for that. You can make enum implement an interface. This interface becomes the super type that can be extended by other enums. GradeCalculable Interface YearLevel Enum Advantage 1.. [Effective Java] Item 37: Using EnumMap as a way to group items by enum Why should you read this article? - You want to group collection into different groups, by enum. - You want to avoid using Set[] and use Map, but want to minimise memory consumption (ie not use HashMap, but something equivalent in memory consumption to simple array that is fixed sized) Let's get started! Oftentimes, a list (or any kind of collection) might need to be grouped into separate groups.. 이전 1 다음
