post past :: james murty

When you work on a Java project with many library dependencies it can be difficult to know which Jar files contain which classes. Hunting down a particular class in a tangled mess of Jar files can be painful, especially if you need to do so on a server over a shell connection.

Here is a handy shell script that iterates over all the Jar archives in a given path, finds those containing file names that match a given pattern, and prints out these matches followed by the name of the Jar file.

#!/bin/sh



if [ -z "$2" ]

then

  echo Usage: $0 Directory ClassName

  exit 1

fi



for f in $(find $1 -name '*.jar')

do

  jar tf $f | grep "$2" && echo "[in $f]"

done

Save this script to a file with an obvious name, like findInJars.sh.

To find all the classes with names containing “HttpClient” in the libs directory, you would invoke the script like so:

$ sh findInJars.sh libs HttpClient



org/apache/commons/httpclient/HttpClient.class

org/apache/commons/httpclient/HttpClientError.class

org/apache/commons/httpclient/params/HttpClientParams.class

[in libs/commons-httpclient/commons-httpclient-3.1.jar]

If you are impatient, you can accomplish the same thing with a big and ugly one-liner:

for f in $(find <b>libs</b> -name '*.jar'); do jar tf $f | grep <b>HttpClient</b> && echo "[in $f]"; done