java - Was my Jar double clicked, or launched from the command line?

Question

My Jar file supports both being clicked, and launched from the command line.

I will only display the GUI if there is a graphics environment available by checking GraphicsEnvironment.isHeadless()

I would like to be able to print logs to a file on disk if the user double clicks the jar file, and print them to the console if launched from the command line.

I have been unable to find an answer to this, are there any cross-platform environment variables, or anything else I can look at to know whether the user launched my program using java -jar app.jar, or whether they double clicked the .jar file?

Answer 1

One way to do this is to determine when the console is null:

public static void main(String[] args) {
    Console console = System.console();
    if(console!=null){
        System.out.println("Console is not null");
    }else{
        System.out.println("Console is null");
    }
}

Try to run the code from the command line using the following command:

java -jar [your_runnable_file.jar]