view java source code

Question

Is any way to view the actual code behind the default classes in Java (java.awt.*;, javax.swing.*;, etc) to see exactly what it is that is happening?

I don't mean just the documentation, or a list of methods, etc, but the source code itself in full detail (in other words, what could be used to create an exact copy of an entire method/class if copied and pasted into the code for a program in Java).

In an IDE such as IntelliJ you can browse the source of these packages just like anything else. — Chris Martin
– Chris Martin, Commented Oct 19, 2014 at 7:24
Extending @ChrisMartin, right click the keyword (e.g. String) in the editor -> "Go to" -> "Implementation(s)" ... as of idea 14.0.2 — ironicaldiction
– ironicaldiction, Commented May 4, 2015 at 14:05

Ernest Friedman-Hill · Accepted Answer · 2011-06-09 05:17:00Z

26

The Java source code for all the API classes is shipped in the JDK installer in a file named src.zip. It's often just sitting in your install directory. Unzip it, and have a look.

If it's not there, you may have chosen not to install it; reinstall the JDK and watch for the "source code" option, making sure to include it.

answered Jun 9, 2011 at 5:17

Ernest Friedman-Hill

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Matt Ball · Accepted Answer · 2011-06-09 05:32:38Z

15

I frequently use http://docjar.com for this purpose.

Example: I want to see the source code for String. Search for the FQCN, java.lang.string (using the "Package/class Name" option). Click the result you want, then click the source link at the top of the page. Voila: http://www.docjar.com/html/api/java/lang/String.java.html

edited Jun 9, 2011 at 5:32

answered Jun 9, 2011 at 5:18

Matt Ball

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3 Comments

Andreas Dolk Over a year ago

grepcode is another great online ressource for quick source code inspection, but as they print linenumbers, copy&paste of code from there into java source files is ... annoying ;)

jkraybill Over a year ago

@Andreas_D - just click the little "Raw" link on the top right of the screen.

Jay Over a year ago

@Andreas_D GrepCode is not working nowadays... Any idea? Have they redirected or something?

Alex Gitelman · Accepted Answer · 2011-06-09 05:17:15Z

4

src.zip usually comes with JDK.

answered Jun 9, 2011 at 5:17

Alex Gitelman

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Community · Accepted Answer · 2020-04-19 21:48:55Z

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I also find http://www.codeatlas.com to be a great place to look for JVM based source code in general. For example, if you are ever looking for how java.awt.ActionEvent is implemented you can find it here:

http://www.codatlas.com/project/L_fXVCOhW4_lzXEd3R5DNQ__/master/src/share/classes/java/awt/event/ActionEvent.java?keyword=ActionEvent&line=59

What's nice about it is that it gives an IDE like browsing experience by adding cross-reference and syntax highlighting.

edited Apr 19, 2020 at 21:48

CommunityBot

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answered Oct 19, 2014 at 6:53

hexabunny

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Alexey Shevelyov Over a year ago

Links are broken.

greenqy · Accepted Answer · 2016-05-24 15:09:20Z

1

For those who use linux distributions, like ubuntu, archlinux, etc. You can always get openjdk source code via corresponding package management system. This means you can choose a faster mirror to get the source code.

For ubuntu users:

$ sudo apt-get install openjdk-7-source

For Archlinux users:

$ sudo pacman -S openjdk7-src

The source will be located in the $JAVA_HOME, somewhere like /usr/lib/jvm/java-7-openjdk/src.zip.

Other distributions will have likewise package names, so not listed here.

answered May 24, 2016 at 15:09

greenqy

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Srujan Kumar Gulla · Accepted Answer · 2012-11-26 02:54:17Z

0

1) Use Eclipse to attach the source code in C:\users\program files\jdkx.x
2) Use GrepCode if you are just browsing the code and to save memory used by heavy weight eclipse on your machine

answered Nov 26, 2012 at 2:54

Srujan Kumar Gulla

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