How does multithreading work in Java?

If you're coming from a systems programming mindset, it's easy to confuse multithreading with multiprocessing. A multithreaded program can manage multiple executions without needing entirely separate processes, which is much lighter on system resources.

You should definitely check out the Java documentation for the `java.lang.Thread` class; it's a great resource for getting started with threads in Java!

To understand multithreading, it helps to know a bit about operating systems. Originally, they only ran one program at a time. Then, with multi-process systems, you could run multiple programs simultaneously. Each process had its own memory segment. This led to multi-threading, where multiple threads can run within a single process and share the same memory space, which makes things easier for both execution and programming. Java has supported threads since its early days and has greatly improved its I/O and concurrency tools over time.

There's a key distinction between processes and threads. A thread is a sequence of instructions executed sequentially, while a process consists of multiple threads that share memory. The CPU rapidly switches between threads to give the illusion of simultaneous execution. Threads in different processes can't access each other's memory, which is crucial for the system's security. Java’s threading functionality is just an easy interface over the operating system's threading capabilities.

Java definitely supports multithreading! It's not about creating a whole new program; it's about having multiple threads running within the same program. If you're curious about how to set up threads in Java, you might want to check out resources on 'making threads in Java' or look into 'virtual threads' from Project Loom if you're using a newer version of Java.