Understanding Java Threads and Concurrency

Textual Information

In Java, a thread represents a single flow of execution within a program. Think of it as a factory with each worker(Thread) working independently on their task and concurrently alongside the other factory workers(Threads).

Detailed Notes on Java Threads and Concurrency

Video Information

Code Snippets

//Threads when Implementing Runnable
public class MyThread implements Runnable {

    public void run() { 
        System.out.println("Running!");
    }

    public static void main(String[] args) {
        MyThread t = new MyThread();
        Thread toRun = new Thread(t);

        toRun.start();
    }
}

//Threads when Extending Thread
public class MyThreadTwo extends Thread {
    public void run() {
        System.out.println("Running!");
    }

    public static void main(String[] args) {
        MyThreadTwo toRun = new MyThreadTwo();

        toRun.start();
    }
}

//Using Synchronized Block to Avoid Race Conditions
public class MyThread implements Runnable {
    private static ArrayList nums;
    public static final Object key = new Object();

    public MyThread() {
        if(nums == null) {
            synchronized(key) {
                if(nums == null) {
                    nums = new ArrayList();
                }
            }
        }
    }

    public void run() { 
        for(int i = 0; i < 100; i++) {
            synchronized(key) {
                nums.add(i);
            }
        }
    }

    public static void main(String[] args) {
        MyThread t = new MyThread();
        Thread t1 = new Thread(t);
        Thread t2 = new Thread(t);
        Thread t3 = new Thread(t);

        t1.start();
        t2.start();
        t3.start();

        try {
            t1.join();
            t2.join();
            t3.join();
        } catch(InterruptedException e) {
            e.printStackTrace();
        }

    }
}
                        

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