What is multi-threading in Java

💡 Concept: Multi-threading in Java

Multi-threading allows concurrent execution of two or more threads to maximize CPU utilization and improve application performance.

📘 Quick Intro

Java supports multi-threading by allowing multiple threads to run concurrently within a program, enabling parallel task execution.

🧠 Analogy

Think of multi-threading as a chef multitasking in the kitchen—preparing multiple dishes simultaneously instead of one after another.

🔧 Technical Explanation

A thread is a lightweight subprocess with its own execution path.
Java supports multi-threading via Thread class and Runnable interface.
Threads share the same process memory but have separate stacks.
Multi-threading improves resource utilization and responsiveness.
Proper synchronization is needed to avoid race conditions.

🎯 Use Cases

✅ Running background tasks like file IO or network operations.
✅ Building responsive UI applications.
✅ Handling multiple client requests in servers.
✅ Parallel processing to reduce computation time.

💻 Java Multi-threading Example


public class MyThread extends Thread {
    public void run() {
        System.out.println("Thread running");
    }
}

public class Demo {
    public static void main(String[] args) {
        MyThread t1 = new MyThread();
        t1.start();
    }
}

❓ Interview Q&A

Q1: What is multi-threading?
A: Concurrent execution of multiple threads.

Q2: How to create a thread in Java?
A: Extend Thread class or implement Runnable.

Q3: What is race condition?
A: When threads access shared data simultaneously causing inconsistency.

Q4: What is synchronization?
A: Mechanism to control thread access to shared resources.

Q5: What is deadlock?
A: A situation where threads wait indefinitely for resources.

Q6: Difference between process and thread?
A: Process is independent, thread is lightweight within process.

Q7: What is thread lifecycle?
A: New, Runnable, Running, Waiting, Terminated.

Q8: How to stop a thread?
A: Use flags or interrupt, stop() is deprecated.

Q9: What is daemon thread?
A: Background thread that terminates when all user threads finish.

Q10: What is thread priority?
A: Determines thread execution order.

📝 MCQs

Q1. What is multi-threading?

Single execution
Concurrent execution
Sequential execution
None

Q2. How to create a thread in Java?

Use main method
Extend Thread class or implement Runnable
Use Executor
Use Interface

Q3. What is race condition?

Deadlock
Race condition
Synchronization
Thread pool

Q4. What is synchronization?

Multithreading
Control thread access
Garbage collection
Exception handling

Q5. What is deadlock?

Deadlock
Livelock
Starvation
Race condition

Q6. Difference between process and thread?

Process is lightweight
Thread is independent
Process is independent, thread is lightweight
None

Q7. What is thread lifecycle?

Start, Stop
New, Runnable, Running, Waiting, Terminated
Created, Dead
None

Q8. How to stop a thread?

stop()
Use flags or interrupt
kill()
None

Q9. What is daemon thread?

User thread
Daemon thread
Main thread
Garbage collector thread

Q10. What is thread priority?

Low priority
High priority
Determines thread execution order
None

💡 Bonus Insight

Multi-threading is essential for building efficient and responsive Java applications.

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