Instead of returning null, you should return a 0-length array or an empty collection in Java

Note: In order to avoid adding null to the array and collection, it is also possible to reduce unnecessary null pointer exceptions, usually in the business to return a zero group or an empty collection.

Method:

1. Array:

Define global static constants to reduce memory overhead: private static final int empty_array = new Int[0], or, of course, direct local variables and so on.

2. Collection:

Use the tool class collections Emptylist () to put back.

Reference:

http://blog.csdn.net/tounaobun/article/details/8502160

Https://www.codeproject.com/Articles/794448/Is-it-Really-Better-to-Return-an-Empty-List-Instea

In Java, you should return a 0-length array or an empty collection instead of returning null (GO)