Java Multithreading Overview

Java Multithreading is a powerful feature that enables the concurrent execution of two or more threads within a program. This capability is crucial for enhancing application performance by utilizing CPU resources more efficiently.

Key Concepts

• Thread: A thread is a lightweight process that can execute independently. Each thread maintains its own call stack and program counter.
• Multithreading: This refers to the ability to run multiple threads simultaneously, leading to improved resource utilization and faster program execution.
• Process vs. Thread:
  • A process is an independent program in execution.
  • A thread is a subset of a process, sharing the same memory space.

Advantages of Multithreading

• Improved Performance: By executing multiple threads, applications can perform tasks faster.
• Resource Sharing: Threads within the same process share resources, facilitating communication and data sharing.
• Better User Experience: Applications can remain responsive while executing background tasks.

Creating Threads in Java

There are two primary methods for creating threads in Java:

1. Extending the Thread Class

• Create a new class that extends Thread.
• Override the run() method to define the code that executes in the thread.

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

public class Main {
    public static void main(String[] args) {
        MyThread thread = new MyThread();
        thread.start(); // Start the thread
    }
}

2. Implementing the Runnable Interface

• Create a class that implements the Runnable interface.
• Provide an implementation for the run() method.

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

public class Main {
    public static void main(String[] args) {
        Thread thread = new Thread(new MyRunnable());
        thread.start(); // Start the thread
    }
}

Thread Lifecycle

Threads in Java progress through several states:

• New: The thread is created but not yet started.
• Runnable: The thread is ready to run and waiting for CPU time.
• Blocked: The thread is waiting for a resource.
• Waiting: The thread is waiting indefinitely for another thread to perform a specific action.
• Terminated: The thread has completed its execution.

Synchronization

• Synchronization is vital to prevent conflicts when multiple threads access shared resources.
• Java provides the synchronized keyword to control access to blocks of code or methods.

public synchronized void synchronizedMethod() {
    // critical section code
}

Conclusion

Java Multithreading is an essential concept for developing efficient and responsive applications. By learning to create and manage threads, developers can leverage the power of concurrent programming in Java.