1、菜单window->Preferences->Java->Editor->Content Assist 恢复默认设置
2、windows-->preference-->workbench-->keys 下设置Content Assist 的快捷键
3、window->Preferences->Java->Editor->Content Assist->Advanced 上面的选项卡select the proposal kinds contained in the 'default' content assist list: 中把 Other Java Proposals 选项打上勾就可以了