Java - Process API Improvements

In Java 9 Process API which is responsible to control and manage operating system processes has been improved considerably. ProcessHandle Class now provides process's native process ID, start time, accumulated CPU time, arguments, command, user, parent process, and descendants. ProcessHandle class also provides method to check processes' liveness and to destroy processes. It has onExit method, the CompletableFuture class can perform action asynchronously when process exits.

Spawning a new Process Example

In this example, we've created a new Process for notepad and started it using ProcessBuilder. Using ProcessHandle.Info interface, we're getting the process information of the newly spawned process.

package com.tutorialspoint;

import java.time.ZoneId;
import java.util.stream.Stream;
import java.util.stream.Collectors;
import java.io.IOException;

public class Tester {
   public static void main(String[] args) throws IOException {
      ProcessBuilder pb = new ProcessBuilder("notepad.exe");
      String np = "Not Present";
      Process p = pb.start();
      ProcessHandle.Info info = p.info();
      System.out.printf("Process ID : %s%n", p.pid());
      System.out.printf("Command name : %s%n", info.command().orElse(np));
      System.out.printf("Command line : %s%n", info.commandLine().orElse(np));

      System.out.printf("Start time: %s%n",
         info.startInstant().map(i -> i.atZone(ZoneId.systemDefault())
         .toLocalDateTime().toString()).orElse(np));

      System.out.printf("Arguments : %s%n",
         info.arguments().map(a -> Stream.of(a).collect(
         Collectors.joining(" "))).orElse(np));

      System.out.printf("User : %s%n", info.user().orElse(np));
   } 
}

Output

You will see the similar output.

Process ID : 5580
Command name : C:\Program Files\WindowsApps\Microsoft.WindowsNotepad_11.2401.26.0_x64__8wekyb3d8bbwe\Notepad\Notepad.exe
Command line : Not Present
Start time: 2024-04-02T17:07:14.305
Arguments : Not Present
User : DESKTOP\Tutorialspoint

Getting Current Process Information Example

In this example, we've getting current process using ProcessHandle.current() method. Then using ProcessHandle.Info interface, we're getting the process information of the current process.

package com.tutorialspoint;

import java.time.ZoneId;
import java.util.stream.Stream;
import java.util.stream.Collectors;
import java.io.IOException;

public class Tester {
   public static void main(String[] args) throws IOException {
      String np = "Not Present";
      ProcessHandle currentProcess = ProcessHandle.current();
      ProcessHandle.Info info = currentProcess.info();
      System.out.printf("Process ID : %s%n", currentProcess.pid());
      System.out.printf("Command name : %s%n", info.command().orElse(np));
      System.out.printf("Command line : %s%n", info.commandLine().orElse(np));

      System.out.printf("Start time: %s%n",
         info.startInstant().map(i -> i.atZone(ZoneId.systemDefault())
         .toLocalDateTime().toString()).orElse(np));

      System.out.printf("Arguments : %s%n",
         info.arguments().map(a -> Stream.of(a).collect(
         Collectors.joining(" "))).orElse(np));

      System.out.printf("User : %s%n", info.user().orElse(np));
   } 
}

Output

You will see the similar output.

Process ID : 5352
Command name : C:\Program Files\Java\jdk-21\bin\javaw.exe
Command line : Not Present
Start time: 2024-04-02T17:09:17.902
Arguments : Not Present
User : DESKTOP-DTHL8BI\Tutorialspoint

Getting Child Processes Example

In this example, we've getting current process chid processes using ProcessHandle.current().children() method. Then using ProcessHandle.Info interface, we're getting the process information of the child processes.

package com.tutorialspoint;

import java.io.IOException;
import java.util.stream.Stream;

public class Tester {
   public static void main(String[] args) throws IOException {
      for (int i = 0; i < 3; i++) {
         ProcessBuilder processBuilder
            = new ProcessBuilder("java.exe", "-version");
         processBuilder.inheritIO().start();
      }
      Stream<ProcessHandle> childProcesses = ProcessHandle.current().children();
      String np = "Not Present";
      childProcesses.filter(ProcessHandle::isAlive).forEach(
         childProcess ->{
            System.out.printf("Process ID : %s%n", childProcess.pid());
            System.out.printf("Command name : %s%n", childProcess.info().command().orElse(np));
            System.out.printf("Command line : %s%n", childProcess.info().commandLine().orElse(np));
         }
      );
   } 
}

Output

You will see the similar output.

Process ID : 5420
Command name : C:\Program Files\Java\jdk-21\bin\java.exe
Command line : Not Present
Process ID : 15796
Command name : C:\Program Files\Java\jdk-21\bin\java.exe
Command line : Not Present
Process ID : 14180
Command name : C:\Program Files\Java\jdk-21\bin\java.exe
Command line : Not Present
java version "21.0.2" 2024-01-16 LTS
Java(TM) SE Runtime Environment (build 21.0.2+13-LTS-58)
Java HotSpot(TM) 64-Bit Server VM (build 21.0.2+13-LTS-58, mixed mode, sharing)
java version "21.0.2" 2024-01-16 LTS
Java(TM) SE Runtime Environment (build 21.0.2+13-LTS-58)
Java HotSpot(TM) 64-Bit Server VM (build 21.0.2+13-LTS-58, mixed mode, sharing)
java version "21.0.2" 2024-01-16 LTS
Java(TM) SE Runtime Environment (build 21.0.2+13-LTS-58)
Java HotSpot(TM) 64-Bit Server VM (build 21.0.2+13-LTS-58, mixed mode, sharing)