Eclipse中找到Windows->preference->java->Editor->ContentAssist->Auto Activation->(勾选复选框)Enable autoactivation->Auto activation trigger for java:后面的框里面填写.abcdefghijklmnopqrstuvwxyz ->点击OK.(重启eclipse，完成)。

如下图：

(1)Windows->preference

(2)preference->java->Editor->ContentAssist->Auto Activation->(勾选复选框)Enable autoactivation

(3)Auto activation trigger for java:后面的框里面填写.abcdefghijklmnopqrstuvwxyz ->点击OK.(重启eclipse，完成)。