Retrieving Process ID of Recently Launched Process in Java Program

When starting a process within a Java program, it is often necessary to retrieve the process ID (PID) for further management or monitoring.

Question:

Consider the following code snippet that initiates a process:

ProcessBuilder pb = new ProcessBuilder("cmd", "/c", "path");
try {
    Process p = pb.start();       
} 
catch (IOException ex) {}

How can we determine the PID of the newly created process using Java?

Answer:

Prior to Java 9, obtaining the PID of a child process involved platform-specific implementations. However, with the introduction of Process API enhancements in Java 9, a simplified approach is now available:

ProcessBuilder pb = new ProcessBuilder("cmd", "/c", "path");
try {
    Process p = pb.start();
    long pid = p.pid();      
} catch (IOException ex) {
    // ...
}

By invoking the pid() method on the Process object, we can directly access the PID of the child process, regardless of the operating system.