Learn Java: Understanding Threads

What is a Thread in Java?

A thread is a smaller unit of a process that can run independently within a program. Java allows multiple threads to run at the same time, making programs run faster by performing tasks concurrently.

Creating a Thread by Extending the Thread Class

You can create a new thread in Java by creating a new class that extends the `Thread` class and overrides its `run()` method.

                                
class MyThread extends Thread {
    public void run() {
        System.out.println("Thread is running");
    }
}
MyThread thread = new MyThread();
thread.start();

                              

Creating Threads Using Lambda Expressions

Java allows you to create threads using lambda expressions, which makes the code more concise and readable.

                                
Thread thread = new Thread(() -> {
    System.out.println("Thread is running");
});
thread.start();

                              

Why Use Threads in Java?

Threads help improve the performance of a program by allowing multiple tasks to run at the same time, especially when the tasks are independent of each other.

Understanding Java Thread Lifecycle

A thread in Java goes through several states during its lifecycle: New (created but not started), Runnable (ready to run), Blocked (waiting for a resource), Waiting (paused indefinitely until notified), Timed Waiting (paused for a specific period), and Terminated (completed execution).

How Threads Communicate in Java

Threads can share information by accessing shared resources or variables. They can also use specific methods to communicate directly with each other.

Java provides methods like `wait()`, `notify()`, and `notifyAll()` to help threads communicate and coordinate with each other.

Managing Java Thread States with Methods

You can control the state of a thread using methods like `start()`, `sleep()`, `wait()`, `notify()`, `join()`, and `interrupt()`.

Avoiding Conflicts with Synchronized in Java

The `synchronized` keyword in Java ensures that only one thread at a time can access a particular block of code or method, preventing conflicts when threads share data.

                                
public synchronized void increment() {
    counter++;
}

                              

What are Race Conditions?

A race condition occurs when two or more threads access shared data at the same time, causing unpredictable results. This happens when threads 'race' each other to complete operations on shared resources.