Java 9 process API improvements

24 Oct 2023

ProcessAPIImprovements

Java 9 introduced several enhancements to the Process API, making it more powerful and flexible for managing and interacting with operating system processes. In this blog post, we’ll explore some of the key improvements in the Process API.

Introduction
New Methods in the Process API
Process Info
Managing Processes with Streams
Conclusion

Introduction

In previous versions of Java, managing processes and interacting with system commands was a somewhat cumbersome task. However, in Java 9, the Process API has been enhanced with new methods to ease the handling of external processes.

New Methods in the Process API

Java 9 introduced three new methods in the java.lang.Process class:

isAlive(): This method returns a boolean value indicating whether the subprocess associated with the Process object is still running.
pid(): The pid() method returns the process identifier of the subprocess. This is particularly useful when you need to obtain the process ID of a running process.
destroyForcibly(): The destroyForcibly() method forcefully terminates the subprocess represented by the Process object. This can be used when you want to forcibly stop a process.

Process Info

With Java 9, you can now retrieve information about the operating system process without resorting to native code. The new ProcessHandle interface provides methods to get process information such as process ID, parent process, command used to launch the process, and more.

ProcessHandle currentProcess = ProcessHandle.current();
long processId = currentProcess.pid();
System.out.println("Current Process ID: " + processId);

Optional<ProcessHandle> parentProcess = currentProcess.parent();
parentProcess.ifPresentOrElse(
    parent -> System.out.println("Parent Process ID: " + parent.pid()),
    () -> System.out.println("Parent process not available.")
);

Managing Processes with Streams

Java 9 introduced the ProcessBuilder class, which allows you to easily build and manage processes with a more streamlined and functional approach. The ProcessBuilder class provides methods to redirect input, output, and error streams. It also provides the ability to chain the process execution using streams.

ProcessBuilder processBuilder = new ProcessBuilder("ls", "-l");

try {
    Process process = processBuilder.start();

    // Read output from the process
    BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()));
    String line;
    while ((line = reader.readLine()) != null) {
        System.out.println(line);
    }

    // Wait for the process to complete
    int exitCode = process.waitFor();
    System.out.println("Process exited with code " + exitCode);
} catch (IOException | InterruptedException e) {
    // Handle exception
}

Conclusion

The improvements in the Java 9 Process API make it easier to work with external processes, retrieve process information, and manage the execution of processes. These enhancements provide a more robust and flexible approach to process management in Java.

These enhancements enable developers to effectively interact with operating system processes, making Java a more powerful language for system-level programming.

References

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