CODEWITHSUNDEEP
javaswingsqlite
KarthickNR
KarthickNR

Reputation: 25

Add files in jar during runtime

Project is to create exe file. If we run exe file it will open one admin page (designed in Swing) that page contains browse button, max install, max install sys, and create build, while click the browse button we need to select one exe file from system and that file need to save it inside one folder of jar file. The maxinstall, max install sys value is stored in SQL lite database. This admin page will open for first time only,to get condition from admin. Next if we run the exe file it must check maxinstall and all parameter and then install that selected exe file.

My problem is, I created jar from my java program. While running the jar each time, the admin page only opening (i.e) the database file is not updated inside jar, but its works fine in eclipse. After that I need to create jar to exe.

Upvotes: 1

Views: 3092

Answers (3)

Surej
Surej

Reputation: 358

Once an executable .jar is created it will be "locked". I you add more files to a locked .jar, those files will not be recognized internally by the .jar itself at runtime. So, the better approach is to extract your dependent .jar and then add it to a new, executible .jar containing the new file(s) that you need. Then moving forward you can run this new .jar.

Upvotes: 0

Andrew Thompson
Andrew Thompson

Reputation: 168845

..it is possible to extract jar in runtime,addfile in the extracted jar and create a new jar in runtime..?

Most JREs will place a file lock on the Jars. Therefore they cannot be updated while the JRE is running. Check a sub-directory of user.home for an altered version of the resource. If it is not found, use the one in the Jar. If it is altered, save the changed data to the sub-dir.

Use a sub-directory based on the package name of the main class, to help avoid overwriting the resources of another app. (or other apps. over-writing your resources).

Upvotes: 4

AlexR
AlexR

Reputation: 115378

I think that I understand your problem. Your application stores its state into its own jar file. the fact that you are using SQLite etc. does not matter. It works from Eclipse because in this case the class files and resources are not packaged into archive and your program changes files on file system easily.

The answer is: yes, you can change jar file programmatically. Jar is just a zip. You can use ZipInputStream, ZipOutputStream, JarInputStream, JarOutputStream to modify any zip including your own.

But it is very very not recommended for too many reasons. The right solution is to separate your data from your application. You have to store runtime data on file system, DB etc. For example you can create files in user home directory. It is platform independent. You can also use Preferences class that has portable implementations for all platforms.

Yet another reason to do this is your requirement to create exe. OK, you can change jar file but once you created exe file from your jar you cannot change it anymore.

Upvotes: 1

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