後來才知道不知怎麼的被取消了Orz
可以先到Windows->Prferences->Editor->Content Assist 確認Auto Activation的勾選
再來就Windows->Prferences->Editor->Content Assist->Advanced 確認Java Non-Type Proposals
物件的宣告等等或相同一樣字的mark沒出現灰色的
Windows->Prferences->Editor->Mark Occurences 確認Mark occurences of the selected element in the current file.
以上
