if your current directory contains all the jar to scan, and the class you are looking for contains a substring like some.package.MyClass:
for i in `ls *.jar`;
do echo $i;
jar -tvf $i | grep some.package.MyClass;
Your jars can be in different subdirectories, at any level, under the current directory. Then you can use:
for i in `find . -name | egrep ".*\.jar$"`;
do echo $i; jar -tvf $i | grep some.package.MyClass;
The result is the list of all the jars, and if a particular jar contains a class that maatches the string you specified (some.package.MyClass), then the complete name of such classe is prompted after the jar.