Question

I’ve been struggling for a while now with this problem and i can’t seem to fix it.
i already have tried different approaches (Runtime.exec(), ProcessBuiler) but none seem to work.

This is my issue.
I have a laptop which is always on. This laptop runs a java tool connected to an arduino via usb to turn on and off the lights in the house. i have created this program myself, therefore i’m also doing some regular maintenance work on it. Recently i have added a button to restart the program from my html interface (in case i have an update, or if for some other reason i might need to restart the program or i decide to implement auto updating in the near future).

This idea behind this is to start a second instance of the application from the first instance and then System.exit(0) the first instance.

For some reason i’m not able to start a second instance of the application.
Here’s some code.

public void shutdown(boolean restart) {
        if (this.serial != null) {
            this.serial.disconnect();
        }

        if (restart) {
            System.out.println(this.getClass().getProtectionDomain().getCodeSource().getLocation().getPath());
            String startupCommand = "java -jar \"" + this.getClass().getProtectionDomain().getCodeSource().getLocation().getPath().replace("%20", " ") + "\"";
            ProcessBuilder builder = new ProcessBuilder();

//            String[] command = new String[1];
//            command[0] = "-jar \"" + (System.getProperty("user.dir") + "/Home_Automation_Executor.jar") + "\"";
            try {
//                //System.out.println("Restarting Home Automation with command: " + command[0]);
//                System.out.println("Restarting Home Automation with command: " + startupCommand);
//                Runtime.getRuntime().exec("bash");
//                Process proc = Runtime.getRuntime().exec(startupCommand);
                Process proc = builder.command(startupCommand).start();
                InputStream stderr = proc.getErrorStream();
                InputStreamReader isr = new InputStreamReader(stderr);
                BufferedReader br = new BufferedReader(isr);
                String line = null;
                System.out.println("<ERROR>");
                while ((line = br.readLine()) != null) {
                    System.out.println(line);
                }
                System.out.println("</ERROR>");
                int exitVal = 0;
                try {
                    exitVal = proc.waitFor();
                } catch (InterruptedException ex) {
                    Logger.getLogger(Engine.class.getName()).log(Level.SEVERE, null, ex);
                }
                System.out.println("Process exitValue: " + exitVal);
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }
        System.out.println("Terminating Home Automation");
        System.exit(0);
    }

java.io.IOException: Cannot run program “java -jar “/Users/NightWalker/Dropbox/Development/Source Code/Java/NightWare Tools/Home Automation/Home Automation Executor/dist/Home_Automation_Executor.jar””: error=2, No such file or directory
at java.lang.ProcessBuilder.start(ProcessBuilder.java:460)
at home.automation.executor.Engine.shutdown(Engine.java:186)
at home.automation.executor.webserver.HTTPGenerator._handleActionCommand(HTTPGenerator.java:190)
at home.automation.executor.webserver.HTTPGenerator._generateHTTPPage(HTTPGenerator.java:165)
at home.automation.executor.webserver.HTTPGenerator.getHTTPPage(HTTPGenerator.java:58)
at home.automation.executor.webserver.HTTPRequestHandler.run(HTTPRequestHandler.java:160)
Caused by: java.io.IOException: error=2, No such file or directory
at java.lang.UNIXProcess.forkAndExec(Native Method)
at java.lang.UNIXProcess.(UNIXProcess.java:53)
at java.lang.ProcessImpl.start(ProcessImpl.java:91)
at java.lang.ProcessBuilder.start(ProcessBuilder.java:453)
… 5 more

Answer 1

The problem is this:

String startupCommand = "java -jar \"" + this.getClass().getProtectionDomain().getCodeSource().getLocation().getPath().replace("%20", " ") + "\"";

/* more stuff */ builder.command(startupCommand);

This means Jav will look for a command named java -jar ...stuff with spaces.... But what you want is, that Java looks for a command named java and give that command several parameters.

You should use

/*...*/ builder.command("java", "-jar", jarLocation) /*...*/