自动代码补全
window–>preference–>java–>Editor–>Auto activation triggers for java后面的.改成abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ
openjdk
下载openjdk
解压
eclipse—>Window—>Preferences—>Java—>Installed JREs—>选择jdk6（我用的版本-_-|||…）—>Edit—>JRE system libraries:—>rt.jar—>Source Attachment—>External Folder…；
选择解压所在目录/jdk/src/share/classes/；
F5刷新