How can I add files to a Jar file?

Question

I want to add a series of files previously extracted from other files(already done) to a jar. These files will be overwriting files inside the JAR. What is the most efficien

Answer 1

 zip file.jar file1 file2 file3 

works for me in Mac Os 10.7.5

Answer 2

jar -uf my.jar file1 file2...
jar -uf my.jar dir/

or mixed

jar -uf my.jar file dir/

Answer 3

//Add a file in jar in a particular folder
jar uvf <jar file name> <file to be added> <folder name inside jar>