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Explain the concept of multithreading in Java

JavaMultithreadingConcurrencyThreads

Question

What is multithreading in Java? Explain thread lifecycle and synchronization.

Answer

Multithreading is the ability of a CPU to execute multiple threads concurrently.


Thread Lifecycle:


1. New: Thread is created but not started

2. Runnable: Thread is ready to run

3. Running: Thread is executing

4. Blocked/Waiting: Thread is waiting for a resource

5. Terminated: Thread execution is complete


Creating Threads:

// Method 1: Extending Thread class
class MyThread extends Thread {
    public void run() {
        System.out.println("Thread running");
    }
}

// Method 2: Implementing Runnable interface
class MyRunnable implements Runnable {
    public void run() {
        System.out.println("Thread running");
    }
}

Synchronization:


Used to prevent thread interference and memory consistency errors.

synchronized void method() {
    // Thread-safe code
}

synchronized (object) {
    // Synchronized block
}

Explanation

Multithreading allows programs to perform multiple tasks simultaneously, improving performance and responsiveness. However, it requires careful handling of shared resources to avoid race conditions and deadlocks.