在按下按钮之前，如何在Java中运行进程？

Question

I'm writing a small program that runs one of three samples of code depending on which button is pressed. With the third button, a sample of code should run until the JFrame is closed, or until a button is pressed (I don't really mind how it's stopped, just as long as the user has a method of stopping the loop). The code is run, and a delay of 8 seconds is added to ensure the code finished running before it loops.

How do I implement this? The program doesn't seem to terminate when looping, even when I try to close it by clicking the close button in the JFrame.

The main part of the program looks as follows:

public class WaspmoteSim extends JFrame implements ActionListener {
public WaspmoteSim() {
    setDefaultCloseOperation(EXIT_ON_CLOSE);

    //getContentPane().setLayout(new GridLayout(1, 3, 10, 10));
    getContentPane().setLayout(new GridBagLayout());
    GridBagConstraints c = new GridBagConstraints();
    c.insets = new Insets(30,30,30,30);
    c.ipadx = 10;
    c.ipady = 30;
    setSize(700, 150);
    setLocation(100, 100);

    JButton button1 = new JButton("Demonstration Mode");
    button1.addActionListener(this);
    add(button1, c);

    JButton button2 = new JButton("Distribution Fitting Mode");
    button2.addActionListener(this);
    add(button2, c);

    JButton button3 = new JButton("Operational Mode");
    button3.addActionListener(this);
    add(button3, c);

    setVisible(true);
}
public static void main(String[] args) {
    new WaspmoteSim();
}

@Override
public void actionPerformed(ActionEvent e) {
    String command = e.getActionCommand();

    if (command.equals("Demonstration Mode")) {
        try {
            DemoMethod();
        } catch (IOException ex) {
            Logger.getLogger(WaspmoteSim.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
    if (command.equals("Distribution Fitting Mode")) {
        try {
            FittingMethod();
        } catch (IOException ex) {
            Logger.getLogger(WaspmoteSim.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
    if (command.equals("Operational Mode")) {
        try {
            OperationsMethod();
        } catch (IOException ex) {
            Logger.getLogger(WaspmoteSim.class.getName()).log(Level.SEVERE, null, ex);
        } catch (InterruptedException ex) {
            Logger.getLogger(WaspmoteSim.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
}

The code that I want to run on a loop looks like this:

public void OperationsMethod() throws IOException, InterruptedException {
        while(true) {
            String workingDir = System.getProperty("user.dir");
            System.out.println(workingDir);
            Process proc;
            proc = Runtime.getRuntime().exec("cmd.exe /C C:\\Progra~1\\R\\R-3.2.1.\\bin\\Rscript.exe " + workingDir + "\\Fitter.r");
            TimeUnit.SECONDS.sleep(8);
        }
    }

Answer 1

The procedure you can follow is this:

1) Create a Process using ProcessBuilder and store it for later use (You can use a holder singleton class "ProcessHolder" for this).

2) Register an event function to your button that takes You register an event function to your button that has access to the ProcessHolder , and terminates the process using destroy() method.

Check for more here .

//Process Holder singleton
public class ProcessHolder {
    private Map<String, Process>  _processes;

    private static ProcessHolder _processHolder;

    private ProcessHolder() {
        _processes = new HashMap<>();
    }

    public static ProcessHolder getInstance() {
        if(_processHolder == null) {
            _processHolder = new ProcessHolder();
        }
        return _processHolder;
    }

    public void getProcesses() {
        return _processes;
    }

}

//......
public class WaspmoteSim extends JFrame implements ActionListener {

    public static final String YOUR_PROCESS_NAME = "Rscript.exe";

    public WaspmoteSim() {
        //....
        JButton button = new JButton("Destroy Process");

        Process process    = Runtime.getRuntime().exec(
            System.getenv("cmd.exe /C C:\\Progra~1\\R\\R-3.2.1.\\bin\\" + YOUR_PROCESS_NAME + " + workingDir + "\\Fitter.r");
        ProcessHolder.getInstance().getProcesses().put(processName, p);
        button.addActionListener(this);
        //....
    }

    //Callback:
    @Override
    public void actionPerformed(ActionEvent e) {
        ProcessHolder.getInstance().getProcesses().get(YOUR_PROCESS_NAME).destroy();
    }

}

Also a notice:

You are doing:

 while(true) {
     Process proc;
     proc = Runtime.getRuntime().exec("cmd.exe /C C:\\Progra~1\\R\\R-3.2.1.\\bin\\Rscript.exe " + workingDir + "\\Fitter.r");
     TimeUnit.SECONDS.sleep(8);
 }

This will attempt to start a new process every 8 seconds (!). In order to start a process, do it once, store it, then kill it when needed using destroy, unless your target is to create new processes like this, indeed.

Answer 2

first define a new boolean variable isClosed in your JFrame add a close-listener to your JFrame and set a boolean variable to true

addWindowListener(new WindowAdapter()
{
    public void windowClosing(WindowEvent e)
    {
        isClosed = true;
    }
});

now change your while(true) to while(!isClosed)