Java 9 has come with the changes which will let you fetch the pid of a process. Following code shows how to get a pid with Java 9

ProcessBuilder pb = new ProcessBuilder("notepad");
		        Process p = pb.start();

		 System.out.println("Pid of Process : " + p.getPid());

getPid function internally call getProcessId0 with process’s handle to retrieve pid. getProcessId0 is a native method.

Apart from process id, other targeted changes are :

• Ability to get/set the process name
• Ability to enumerate Java virtual machines and processes to get pid, name, state, and perhaps resource usage
• Api to do “End Process Tree”. 

Thanks Robin for the update, JDK 9 docs are now available here http://download.java.net/jdk9/docs/api/java/lang/ProcessBuilder.html

1. JEP 102- Process API Updates
2. JEP 143- Improve Contended Locking
3. JEP 158- Unified JVM Logging
4. JEP 165- Compiler Control
5. JEP 197- Segmented Code Cache
6. JEP 199- Smart Java Compilation, Phase Two
7. JEP 201- Modular Source Code
8. JEP 211- Elide Deprecation Warnings on Import Statements
9. JEP 212- Resolve Lint and Doclint Warnings
10. JEP 213- Milling Project Coin
11. JEP 214- Remove GC Combinations Deprecated in JDK 8
12. JEP 216- Process Import Statements Correctly
13. JEP 217- Annotations Pipeline 2.0
14. JEP 219- Datagram Transport Layer Security (DTLS)
15. JEP 220- Modular Run-Time Images
16. JEP 224- HTML5 Javadoc
17. JEP 228- Add More Diagnostic Commands
18. JEP 229- Create PKCS12 Keystores by Default
19. JEP 230- Microbenchmark Suite
20. JEP 231- Remove Launch-Time JRE Version Selection
21. JEP 235- Test Class-File Attributes Generated by javac
22. JEP 236- Parser API for Nashorn
23. JEP 237- Linux/AArch64 Port