How to get a list of current open windows/process with Java?

This is another approach to parse the the process list from the command "ps -e":

try {
    String line;
    Process p = Runtime.getRuntime().exec("ps -e");
    BufferedReader input =
            new BufferedReader(new InputStreamReader(p.getInputStream()));
    while ((line = input.readLine()) != null) {
        System.out.println(line); //<-- Parse data here.
    }
    input.close();
} catch (Exception err) {
    err.printStackTrace();
}

If you are using Windows, then you should change the line: "Process p = Runtime.getRun..." etc... (3rd line), for one that looks like this:

Process p = Runtime.getRuntime().exec
    (System.getenv("windir") +"\\system32\\"+"tasklist.exe");

Hope the info helps!

The only way I can think of doing it is by invoking a command line application that does the job for you and then screenscraping the output (like Linux's ps and Window's tasklist).

Unfortunately, that'll mean you'll have to write some parsing routines to read the data from both.

Process proc = Runtime.getRuntime().exec ("tasklist.exe");
InputStream procOutput = proc.getInputStream ();
if (0 == proc.waitFor ()) {
    // TODO scan the procOutput for your data
}

YAJSW (Yet Another Java Service Wrapper) looks like it has JNA-based implementations of its org.rzo.yajsw.os.TaskList interface for win32, linux, bsd and solaris and is under an LGPL license. I haven't tried calling this code directly, but YAJSW works really well when I've used it in the past, so you shouldn't have too many worries.

There is no platform-neutral way of doing this. In the 1.6 release of Java, a "Desktop" class was added the allows portable ways of browsing, editing, mailing, opening, and printing URI's. It is possible this class may someday be extended to support processes, but I doubt it.

If you are only curious in Java processes, you can use the java.lang.management api for getting thread/memory information on the JVM.

This might be useful for apps with a bundled JRE: I scan for the folder name that i'm running the application from: so if you're application is executing from:

C:\Dev\build\SomeJavaApp\jre-9.0.1\bin\javaw.exe

then you can find if it's already running in J9, by:

public static void main(String[] args) {
    AtomicBoolean isRunning = new AtomicBoolean(false);
    ProcessHandle.allProcesses()
            .filter(ph -> ph.info().command().isPresent() && ph.info().command().get().contains("SomeJavaApp"))
            .forEach((process) -> {
                isRunning.set(true);
            });
    if (isRunning.get()) System.out.println("SomeJavaApp is running already");
}

The below program will be compatible with Java 9+ version only...

To get the CurrentProcess information,

public class CurrentProcess {
    public static void main(String[] args) {
        ProcessHandle handle = ProcessHandle.current();
        System.out.println("Current Running Process Id: "+handle.pid());
        ProcessHandle.Info info = handle.info();
        System.out.println("ProcessHandle.Info : "+info);
    }
}

For all running processes,

import java.util.List;
import java.util.stream.Collectors;

public class AllProcesses {
    public static void main(String[] args) {
        ProcessHandle.allProcesses().forEach(processHandle -> {
            System.out.println(processHandle.pid()+" "+processHandle.info());
        });
    }
}

    String line;
    Process process = Runtime.getRuntime().exec("ps -e");
    process.getOutputStream().close();
    BufferedReader input =
            new BufferedReader(new InputStreamReader(process.getInputStream()));
    while ((line = input.readLine()) != null) {
        System.out.println(line); //<-- Parse data here.
    }
    input.close();

We have to use process.getOutputStream.close() otherwise it will get locked in while loop.

This is my code for a function that gets the tasks and gets their names, also adding them into a list to be accessed from a list. It creates temp files with the data, reads the files and gets the task name with the .exe suffix, and arranges the files to be deleted when the program has exited with System.exit(0), it also hides the processes being used to get the tasks and also java.exe so that the user can't accidentally kill the process that runs the program all together.

private static final DefaultListModel tasks = new DefaultListModel();

public static void getTasks()
{
    new Thread()
    {
        @Override
        public void run()
        {
            try 
            {
                File batchFile = File.createTempFile("batchFile", ".bat");
                File logFile = File.createTempFile("log", ".txt");
                String logFilePath = logFile.getAbsolutePath();
                try (PrintWriter fileCreator = new PrintWriter(batchFile)) 
                {
                    String[] linesToPrint = {"@echo off", "tasklist.exe >>" + logFilePath, "exit"};
                    for(String string:linesToPrint)
                    {
                        fileCreator.println(string);
                    }
                    fileCreator.close();
                }
                int task = Runtime.getRuntime().exec(batchFile.getAbsolutePath()).waitFor();
                if(task == 0)
                {
                    FileReader fileOpener = new FileReader(logFile);
                    try (BufferedReader reader = new BufferedReader(fileOpener))
                    {
                        String line;
                        while(true)
                        {
                            line = reader.readLine();
                            if(line != null)
                            {
                                if(line.endsWith("K"))
                                {
                                    if(line.contains(".exe"))
                                    {
                                        int index = line.lastIndexOf(".exe", line.length());
                                        String taskName = line.substring(0, index + 4);
                                        if(! taskName.equals("tasklist.exe") && ! taskName.equals("cmd.exe") && ! taskName.equals("java.exe"))
                                        {
                                            tasks.addElement(taskName);
                                        }
                                    }
                                }
                            }
                            else
                            {
                                reader.close();
                                break;
                            }
                        }
                    }
                }
                batchFile.deleteOnExit();
                logFile.deleteOnExit();
            } 
            catch (FileNotFoundException ex) 
            {
                Logger.getLogger(Functions.class.getName()).log(Level.SEVERE, null, ex);
            } 
            catch (IOException | InterruptedException ex) 
            {
                Logger.getLogger(Functions.class.getName()).log(Level.SEVERE, null, ex);
            }
            catch (NullPointerException ex)
            {
                // This stops errors from being thrown on an empty line
            }
        }
    }.start();
}

public static void killTask(String taskName)
{
    new Thread()
    {
        @Override
        public void run()
        {
            try 
            {
                Runtime.getRuntime().exec("taskkill.exe /IM " + taskName);
            } 
            catch (IOException ex) 
            {
                Logger.getLogger(Functions.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
    }.start();
}