window->Preferences->Java->Editor->Content Assist
auto activaction -> Enable auto activation -> Auto Activation triggers for java “.abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ,([{”
window->Preferences->Java->Editor->Content Assist->Advanced Select the proposal kinds contained in the 'default' content assist list中全部勾上！