To check whether an application is running or not using java?

Question

I have a java application which start an another java application (third party) in background, so before launching third party background application I want to check whether that application is already running or not(don't want to wait for termination of that application).
I am using the following code for launching the third party java application :

String path = new java.io.File("do123-child.cmd").getCanonicalPath();
Runtime.getRuntime().exec(path);

Note : file "do123-child.cmd" call a ".bat" file to run that application.

To check whether a given application is running or not I am using following code [ Ref link ]:

boolean result = false;
try {
    String line;
    Process p = Runtime.getRuntime().exec("tasklist.exe");
    BufferedReader input =
            new BufferedReader(new InputStreamReader(p.getInputStream()));
    while ((line = input.readLine()) != null) {
        if(line.startsWith("myApp.exe")){
            result = true;
            break;
        }
     }
     input.close();
} catch (Exception err) {
     err.printStackTrace();
}
return result;

I want to know whether is there any another way to do this without iterating the all processes currently running ? Like :

Process p = Runtime.getRuntime().exec("tasklist /FI \"IMAGENAME eq myApp.exe\" /NH");
int exitVal = p.exitValue();
//if above code throw "java.lang.IllegalThreadStateException" means application is running.

but above code return 0 for all application.

Thanks in advance.

Answer 1

You could use jps to inspect the Java applications running. jps is bundled with the JRE.

jps -l
19109 sun.tools.jps.Jps
15031 org.jboss.Main
14040 
14716

You could scrape the list from this program using Runtime.getRuntime().exec() and reading the input stream, then search the package names for a match within Java.

Since you want to avoid iterating all the results, you could grep the result using findstr to return the basic p.exitValue() result you are looking for:

Process p = Runtime.getRuntime().exec("jps -l | findstr /R /C:\"com.myapp.MyApp\"");
int exitVal = p.exitValue(); // Returns 0 if running, 1 if not

Of course findstr is Windows-specific, so you'll need to use grep instead on the Mac:

Process p = Runtime.getRuntime().exec("jps -l | grep \"com.myapp.MyApp\"");
int exitVal = p.exitValue(); // Returns 0 if running, 1 if not

The jps tool uses an internal API (MonitoredHost) to obtain this information, so you could do this entirely within Java as well:

String processName = "com.myapp.MyApp";

boolean running = false;
HostIdentifier hostIdentifier = new HostIdentifier("local://localhost");

MonitoredHost monitoredHost;
monitoredHost = MonitoredHost.getMonitoredHost(hostIdentifier);

Set activeVms = monitoredHost.activeVms();
for (Object activeVmId : activeVms) {
    VmIdentifier vmIdentifier = new VmIdentifier("//" + String.valueOf(activeVmId) + "?mode=r");
        MonitoredVm monitoredVm = monitoredHost.getMonitoredVm(vmIdentifier);
    if (monitoredVm != null) {
        String mainClass = MonitoredVmUtil.mainClass(monitoredVm, true);
        if (mainClass.toLowerCase().equals(processName.toLowerCase())) {
            running = true;
            break;
        }
    }
}

System.out.print(running);