Open a file with its associated application and extra command line parameters

Question

I would like to open a file with its associated application and a couple of command line parameters.

E.g. the_app.exe -someoption file.app, the_app.exe being the associated application for opening the .app files.

I was looking to the Desktop class with the hope to find either

• a Desktop.getDesktop().open(file,options), or
• a Desktop.getDesktop().getOpenFileHandler(file) and then build upon that with Process and ProcessBuilder

Neither do exist. Any other suggestion ?

Answer 1

In java you can use Runtime to run programs.

Runtime.getRuntime().exec("program");

You can also use "cmd" to run command-line commands.

Then, if option parameters weren't needed, you could simply use 'start' command.

//this will open notepad in my pc
Process pr = Runtime.getRuntime().exec("cmd /c start test.txt");

If you really need to pass commands you can use some auxiliar commands and build your own command-line:

With 'assoc' you retrieve the filetype

With 'ftype' you retrieve the application for a filetype

Then:

private static String command(Runtime rt, String command) throws IOException {
    Process pr = rt.exec("cmd /c " + command);
    try (BufferedReader reader = new BufferedReader(new InputStreamReader(pr.getInputStream()))){
        return reader.readLine();
    }
}

public static void main(String[] args) throws IOException {
    //without parameters is an easy job
    Process pr = Runtime.getRuntime().exec("cmd /c start test.txt");

    //with parameters things get messy
    Runtime rt = Runtime.getRuntime();
    String out1 = command(rt, "assoc .txt");
    System.out.println(out1);
    String assoc = out1.split("=")[1];
    String out2 = command(rt, "ftype " + assoc);
    System.out.println(out2);
    String app = out2.split("=")[1].split(" ")[0]; //error prone, consider using regex
    command(rt, app + " /P test.txt"); //This will print (/P) the file using notepad

}

Of course, none of these are portable at all.

For more info:

Running Command Line in Java

Best way to get file type association in Windows 10 from command line?

https://www.addictivetips.com/windows-tips/file-app-association-command-prompt-windows-10/

How to open file with default application in cmd?