Viewing contents of a .jar file

Question

What would be the easiest way to view classes, methods, properties, etc. inside a jar file? I'm looking for something equivalent to the very useful Lutz Roeder .NET Reflector - for Java

Answer 1

Using the JDK, jar -tf will list the files in the jar. javap will give you more details from a particular class file.

Answer 2

I usually open them with 7-Zip... It allows at least to see packages and classes and resources.
Should I need to see methods or fields, I would use Jad but of course, it is better to rely on (good) JavaDoc...

Now, somewhere on SO was mentioned some Eclipse plug-ins, to find in which jar file a class is located, perhaps they can do more (ie. what you requested).

[EDIT] Reference to SO thread. Not what is asked, but somehow related, thus useful: Java: How do I know which jar file to use given a class name?

Answer 3

What I use personally is JD-GUI. It is a free 'decompiler', as it allows you to see the source code, classes, and objects in the classes, as well as see the file structure in a tree menu to the left. However, it does not allow you to modify the classes directly.

JD-GUI's website: http://jd.benow.ca/

Answer 4

Method names, fields, etc.

By adding a jar to a project in an IDE, you can usually see methods and field names, but not the detailed implementation. NetBeans can do it, Eclipse probably, IntelliJ probably, etc. You can browse the jar structure directly within the IDE.

Just the contents

For anything such as viewing the contents, you could use :

• jar tvf jarfile.jar
• winzip or any zip tool

The source code

To access source code, you would use a decompiler such as JAD or one of its frontends or another decompiler. If the code is obfuscated, then ...

Answer 5

In case someone don't know this already, a JAR file is just a ZIP file that contains the program's classes, resources, etc., and some metadata. You can extract one to see how it's put together.

Hence I am using unzip command which is easy to remember and use.

unzip -l <jar-file-name>.jar

For example, if you have a jar file with name test.jar then unzip -l test.jar will list all the content of jar file.

While all other answers are great, but in most of them, you would have to use some software like 7 zip or JDK or some other eclipse tool while this doesn't require you to have any of these big s/w and it comes by default in linux and mac so its very lightweight and handy to use .

You can also use zipinfo <your jar file> . if your OS supports this.

Answer 6

Extending Tom Hawtin answer, you can pipe the listing to filter out desired class or files:

jar tf my-fat-jar-file.jar | grep filename

This should work on bash/zsh and similars, or emacs' eshell.

Additional information: https://docs.oracle.com/javase/tutorial/deployment/jar/view.html

Answer 7

Use WinRar . It will open the folder structure for you in intact manner. Also allows in-archive editing, while preserving paths.

Afterall, a JAR file is a ZIP archive only.

Answer 8

If you like to see whats inside, simply rename as first option below..

1. F2 & Rename to jarfile.zip //Use any unzipper...

2. jar tvf jarfile.jar

3. jar tf jarfile.jar

Answer 9

If I understand correctly, you want to see not only classes but also methods, properties and so on. The only tool I know that can do it is Eclipse - if you add a jar to project classpath, you would be able to browse its classes with methods and properties using usual package explorer.

Anyway, this is a good idea for a good standalone Java tool

Answer 10

Jad is klunky and no longer maintained. I've switched to "Java Decompiler" , which has a slick UI and support for new language features.

Every decompiler I've used, though, runs into code it doesn't successfully decompile. For those, it helps to understand the disassembled Java byte code produced by the standard JDK tool, javap .

Answer 11

jar -tvf file_name.jar

above will only print names of the files .

To view the content of files, you can extract the files in a folder by:

jar -xvf file_name.jar

this will unzip jar file & put the content in same directory where you are running this.

Or in Windows rename .jar file to .zip & then you can unzip to extract & view the content of jar file. As jar is internally a zip file.

Answer 12

如果您在Windows中并使用Powershell，并且正在jar中寻找文件，则可以执行以下操作：

jar -tf .\[JAR_NAME] | where {$_ -match "[FILENAME]"}

Answer 13

One way to do this is to open the perspective in "Package explorer". Doing this you can see the structure of your jar with class details. For this check the library folder in your project using package explorer.

Window>>Show View>>Other>>Java>>Package Explorer

Another way is, you can use JarPlug as a eclipse plugin. This works in eclipse/springsource

http://jar-plug.sourceforge.net/

Answer 14

Well, a jar-file is just a zip-file, so if you unzip it (with your favorite unzipping utility), you get all the files inside.

If you want to look inside the class files to see the methods, you'll need a tool for that. As PhiLho mentions, Eclipse is able to do that (by default), and I would think most Java IDEs are capable of that.

Answer 15

In Eclipse 3.4 do

1. Drag the jar file in question into a Java project. A copy of the jar file appears.
2. Right click on the jar file, and choose "Build Path" -> "Add to Build Path".
3. Jar file is moved to "Referenced Libraries" node, where it can be opened and navigated in the Project Explorer pane.

If seeing source code too is an issue, open a new question.

For navigation on Jar-file level (as a zip file) I use 7zip which works very well, and allows seeing and editing entries which is great for trouble shooting.

Answer 16

Bndtools provides a free JAR viewer plugin for Eclipse.

Add the Eclipse update site and install only the viewer.

Answer 17

如今，您可以使用大多数解压缩工具打开它们，然后，如果要查看源代码，则只需获得DJ Java Decompiler之类的东西即可。

Answer 18

我更喜欢JAR Browser ，它具有一个简单的界面，您可以在其中浏览多个JAR，并同时在多个JAR中搜索特定的类。

Answer 19

Eclipse 3.4 JDT

It is not the quickest way because you have to drag it into your eclipse first. But you will have full java class browsing, even with decompile enabled.

Answer 20

I think Java Decomplier is your best option you can download from here: http://jd.benow.ca/

Answer 21

I've set the default action in windows to "Open with WinZip". This makes it easy to manage JARs as archives. You can even add/remove files manually.

Answer 22

My requirement was to view the content of a file (like a property file) inside the jar, without actually extracting the jar. If anyone reached this thread just like me, try this command -

unzip -p myjar.jar myfile.txt

This worked well for me!

Answer 23

我使用JarExplorer或JarVisualizer 。

Answer 24

您可以尝试JarNavigator来查看和搜索jar文件的内容。

Answer 25

You could try JarSpy . There is an IDEA plugin version of it that I use.

Answer 26

Your IDE should also support this. My IDE (SlickeEdit) calls it a "tag library." Simply add a tag library for the jar file, and you should be able to browse the classes and methods in a hierarchical manner.

Answer 27

java -xf some-j.jar将解压缩JAR文件。

Answer 28

您也可以使用Luyten-开源Java Decompiler Gui

Answer 29

在Mac上有Jarzilla

Answer 30

This Jar Explorer is good enough.
Supports three decompiler types: JD, Procyon and Fernflower.
Allows to search files and duplicates in any java archive.
Also user can modify jar by D&D files and edit some non-class files.