How do I add the Java API documentation to Eclipse?

To use offline Java API Documentation in Eclipse, you need to download it first. The link for Java docs are (last updated on 2013-10-21):

Java 6
Page: http://www.oracle.com/technetwork/java/javase/downloads/jdk-6u25-doc-download-355137.html
Direct: http://download.oracle.com/otn-pub/java/jdk/6u30-b12/jdk-6u30-apidocs.zip

Java 7
Page: http://www.oracle.com/technetwork/java/javase/documentation/java-se-7-doc-download-435117.html

Java 8
Page: http://www.oracle.com/technetwork/java/javase/documentation/jdk8-doc-downloads-2133158.html

Java 9
Page:http://www.oracle.com/technetwork/java/javase/documentation/jdk9-doc-downloads-3850606.html

1. Extract the zip file in your local directory.
2. From eclipse Window --> Preferences --> Java --> "Installed JREs" select available JRE (jre6: C:\Program Files (x86)\Java\jre6 for instance) and click Edit.
3. Select all the "JRE System libraries" using Control+A.
4. Click "Javadoc Location"
5. Change "Javadoc location path:" from "http://download.oracle.com/javase/6/docs/api/" to "file:/E:/Java/docs/api/".

It must work as it works for me. I don't need Internet connection to view Java API Documentation in Eclipse anymore.

Eclipse doesn't pull the tooltips from the javadoc location. It only uses the javadoc location to prepend to the link if you say open in browser, you need to download and attach the source for the JDK in order to get the tooltips. For all the JARs under the JRE you should have the following for the javadoc location: http://java.sun.com/javase/6/docs/api/. For resources.jar, rt.jar, jsse.jar, jce.jar and charsets.jar you should attach the source available here.

Old question, but I had current problems with this issue. So I provide you my solution. Now the sources and javadocs are inside the jdk. So, unzip your jdk version.You can see that contanins a "src.zip" file. Here are your needed sources and doc files. Follow the path: Window->Preferences->Java->Installed JREs-> select your jre/jrd and press "Edit" Select all .jar files, and press Source Attachement. Select the "External File..." button, and point it to src.zip file.

Maibe a restart to Eclipse is needed. (normally not) Now you should see the docs, and also the sources for the classes from jdk.

For offline Javadoc from zip file rather than extracting it.

Why this approach?

This is already answered which uses extracted zip data but it consumes more memory than simple zip file.

Comparison of zip file and extracted data.

jdk-6u25-fcs-bin-b04-apidocs.zip  --->  ~57 MB
after extracting this zip file  --->  ~264 MB !

So this approach saves my approx. 200 MB.

How to use apidocs.zip?

1.Open Windows -> Preferences

2.Select jre from Installed JREs then Click Edit...

3.Select all .jar files from JRE system libraries then Click Javadoc Location...

4.Browse for apidocs.zip file for Archive path and set Path within archive as shown above. That's it.

5.Put cursor on any class name or method name and hit Shift + F2