Java Multithreading/Concurrency

What is multithreading in Java?

Multithreading in Java is a feature that allows for the concurrent execution of two or more parts of a program, known as threads, to maximize the utilization of the CPU. Each thread can run in parallel with others, sharing the same memory space. Key Concepts Thread: A thread is a lightweight sub-process, the smallest unit of processing. Multiple threads can exist within a single process. Concurrency vs. Parallelism: Concurrency: Multiple threads make progress in an interleaved manner on a single CPU core. The system switches between threads, giving the illusion of simultaneous execution. Parallelism: Multiple threads run simultaneously on different CPU cores. This is true parallel execution. Main Purpose: Performance: To perform CPU-intensiv…

What is multithreading in Java?

How to Create Threads in Java There are two primary ways to create a thread: Implementing the Runnable Interface (Preferred Method): Create a class that implements the java.lang.Runnable interface. Implement the run() method, which contains the code to be executed by the thread. Create an instance of the Thread class, passing your Runnable object to its constructor, and call the start() method.

class MyRunnable implements Runnable {
public void run() {
System.out.println("Thread is running by implementing Runnable.");
}
}

// To start the thread:
MyRunnable myRunnable = new MyRunnable();
Thread thread = new Thread(myRunnable);
thread.start();

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

// To start the thread:
MyThread thread = new MyThread();
thread.start();

What are the different state of thread.

In Java, a thread can be in one of the following states, which are defined in the java.lang.Thread.State enum: NEW A thread that has been created but has not yet started. It remains in this state until the start() method is invoked on it. RUNNABLE A thread that is executing in the Java Virtual Machine (JVM). A thread in this state is either currently running or is ready to run and waiting for its turn to be selected by the thread scheduler. BLOCKED A thread that is waiting to acquire a monitor lock to enter a synchronized block or method. It is blocked because another thread currently holds the lock. WAITING A thread that is waiting indefinitely for another thread to perform a particular action. A thread enters this state by calling one of the following methods:

Object.wait() (with no timeout)
Thread.join() (with no timeout)
LockSupport.park()

TIMED_WAITING A thread that is waiting for a specified period of time. A thread enters this state by calling one of these methods with a timeout value:

Thread.sleep(long millis)
Object.wait(long timeout)
Thread.join(long millis)
LockSupport.parkNanos(long nanos)
LockSupport.parkUntil(long deadline)

TERMINATED A thread that has completed its execution. This happens when its run() method has finished, either by completing normally or by throwing an unhandled exception

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