Q 25 - Thread LifeCycle

[AmjustGettingStarted]

Explain Java Thread Life Cycle..?

[HARSHITH-MV]

Here’s a clean and complete explanation of the Java Thread Life Cycle, based on your GitHub discussion titled “Q 25 - Thread LifeCycle” and enriched with practical insights:

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🔄 Java Thread Life Cycle

A thread in Java goes through several distinct states during its execution. These are defined in the java.lang.Thread.State enum.

🧵 1. New

• Description: Thread is created but not yet started.
• Code: Thread t = new Thread();

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▶️ 2. Runnable

• Description: Thread is ready to run and waiting for CPU time.
• Code: t.start();
• Note: It doesn’t mean it’s running — just eligible to run.

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🏃 3. Running

• Description: Thread is actively executing.
• Managed by: JVM thread scheduler.
• Note: You can’t force a thread into this state manually.

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⏸️ 4. Blocked

• Description: Thread is waiting to acquire a lock (e.g., synchronized block).
• Occurs When: Another thread holds the lock the current thread needs.

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💤 5. Waiting

• Description: Thread is waiting indefinitely for another thread to signal.
• Methods: wait(), join(), park()
• Note: Must be explicitly notified to resume.

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⏳ 6. Timed Waiting

• Description: Thread waits for a specified time.
• Methods: sleep(ms), wait(ms), join(ms)
• Example: Thread.sleep(1000);

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🛑 7. Terminated (Dead)

• Description: Thread has finished execution or was stopped due to an error.
• Code: Happens automatically after run() completes.

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🧠 Visual Summary

New → Runnable → Running → (Waiting / Timed Waiting / Blocked) → Terminated

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