Windows -> Preferences. 
2.Select jre from Installed
JREs then hit Edit botton on the
right.
3.browse the installed jre path for the jre home.
4.Select xx.rt.jar item of the ‘JRE system libraries‘ and hit ‘Javadoc Location‘.
5.Select ‘Javadoc in archive‘ radiobutton,select the ‘External file‘
item,browse for apidocs.zip file
for Archive path and
set Path within archive as shown
above.
javadoc in archive eclipse.,布布扣,bubuko.com
原文：http://www.cnblogs.com/listened/p/3720311.html