How Can a JAR File Delete Itself?

Question

I need a JAR file to delete itself.

The issue is that Windows locks the JAR file while it is running, and can't delete itself directly.

I have looked into solutions where a batch script could kill the JAR process and then delete the file, but

• System.exit(0) is not desired because it is not runnable via Batch file.
• taskkill /F /IM "java.exe" is not desired because it kills ALL Java processes.
• jps cannot be used because it is only available in the JDK and users might run a JRE so that would fail.

---

I'm stuck on looking for a solution which lets me find the PID of the current JAR using Java code, then writing out a Batch command and inserting the PID which kills the process e.g. like the following:

printWriter.println("taskkill /PID " + currentJARPID);

If you're wondering what this is for, you can check this answer.

Answer 1

Here is a working example

public class Delete
{
    public static void main(String[] args) throws Throwable
    {
        System.out.println("Running");

        System.out.println("Deleting");
        Runtime.getRuntime().exec("cmd /c ping localhost -n 6 > nul && del Delete.jar");

        System.out.println("Ending");
        System.exit(0);
    }
}

The main feature powering this is cmd /c ping localhost -n 6 > nul && del Delete.jar

It deletes the jar file after waiting 5 seconds

To test, I used javac Delete.java && jar cfe Delete.jar Delete Delete.class to build the jar, and java -jar Delete.jar to run

I also verified that I could not delete the jar file while it was executing, through new File("Delete.jar").delete(); and also using Windows Explorer