Question

I have made a Swing application and will include a file, help.pdf in the .jar file. When the user selects Help->User Guide from a JMenuItem, it should load the file in the default PDF viewer on the system.

I have the code to load the PDF,

private void openHelp() {
    try {
        java.net.URL helpFile = getClass().getClassLoader().getResource("help.pdf");
        File pdfFile = new File(helpFile.getPath());
        if (pdfFile.exists()) {

            if (Desktop.isDesktopSupported()) {
                Desktop.getDesktop().open(pdfFile);
            } else {
                System.out.println("Awt Desktop is not supported!");
            }

        } else {
            System.out.println("File does not exist!");
        }

        System.out.println("Done");

    } catch (Exception ex) {
        ex.printStackTrace();
    }

}

This works in the eclipse IDE, however, when I pack it into a jar for other people it no longer works.

How do I fix this problem?

Answer 1

The problem is that a File cannot name a component of a JAR file. What you need to do is to copy the resource from the JAR file into a temporary file in the filesystem, and open using the File for the temporary file.