Eclipse -> Perferences -> Java -> Editor -> Content Assist如下图.
将auto activation triggers for java
内容改为
.abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ
并选择Apply and Close.
参考：
https://blog.csdn.net/cloudyunmz/article/details/93403008
原文：https://www.cnblogs.com/sea-stream/p/11601070.html