Extracting .jar file with command line

Question

From the docs:

To extract the files from a jar file, use x, as in:

C:\Java> jar xf myFile.jar

To extract only certain files from a jar file, supply their filenames:

C:\Java> jar xf myFile.jar foo bar

The folder where jar is probably isn't C:\Java for you, on my Windows partition it's:

C:\Program Files (x86)\Java\jdk[some_version_here]\bin

Unless the location of jar is in your path environment variable, you'll have to specify the full path/run the program from inside the folder.

EDIT: Here's another article, specifically focussed on extracting JARs: http://docs.oracle.com/javase/tutorial/deployment/jar/unpack.html

Note that a jar file is a Zip file, and any Zip tool (such as 7-Zip) can look inside the jar.

In Ubuntu:

unzip file.jar -d dir_name_where_extracting

You can use the following command: jar xf rt.jar

Where X stands for extraction and the f would be any options that indicate that the JAR file from which files are to be extracted is specified on the command line, rather than through stdin.

Java has a class specifically for zip files and one even more specifically for Jar Files.

java.util.jar.JarOutputStream
java.util.jar.JarInputStream

using those you could, on a command from the console, using a scanner set to system.in

Scanner console = new Scanner(System.in);
String input = console.nextLine();

then get all the components and write them as a file.

JarEntry JE = null;
while((JE = getNextJarEntry()) != null)
{
    //do stuff with JE
}

You can also use java.util.zip.ZipInputStream instead, as seeing a JAR file is in the same format as a ZIP file, ZipInputStream will be able to handle the Jar file, in fact JarInputStream actually extends ZipInputStream.

an alternative is also instead of getNextJarEntry, to use getNextEntry