Joining Threads

Thu, 26 Mar 2026 00:00:00 +0000

Thread Coordination - Part 2: Joining Threads

1. The Problem: The “Race” to the Finish

When you start a thread, it runs independently. If the main thread needs the result of Thread-A to perform a calculation, main might finish before Thread-A even starts, leading to null results or crashes.

2. The Solution: `thread.join()`

The join() method allows the calling thread (e.g., main) to go into a Waiting state until the target thread finishes its execution.

Thread Termination & Daemon Threads

Thu, 26 Mar 2026 00:00:00 +0000

Thread Termination & Daemon Threads

1. Why is Termination Tricky?

Threads consume resources (Memory, CPU, File Handles). If a thread finishes its task but stays alive, it’s a Resource Leak.

We cannot use the stop() method (it is deprecated and dangerous).
We must use Cooperative Termination.

2. Method 1: The Interrupt Signal

Interrupting is a way for one thread to signal another: “Please stop what you are doing.”

Scenario A: Thread is Blocking (Sleeping/Waiting)

If a thread is executing a method like Thread.sleep() or wait(), it will throw an InterruptedException when interrupted.

Thread Coordination on Study Notes

Joining Threads

Thread Coordination - Part 2: Joining Threads

1. The Problem: The “Race” to the Finish

2. The Solution: thread.join()

Thread Termination & Daemon Threads

Thread Termination & Daemon Threads

1. Why is Termination Tricky?

2. Method 1: The Interrupt Signal

Scenario A: Thread is Blocking (Sleeping/Waiting)

2. The Solution: `thread.join()`