1. Threads in Java

Java provides core language support for threads. All Java programs are threaded by default even when they are not explicitly created.

The JVM itself creates a number of threads, incl. some background tasks to handle garbage collection, UI updates (JavaFX), etc.

Creating Threads

There are multiple approaches to creating threads:

• Create a new class that extends Thread class and overrides run() method.

  class Example extends Thread {
      @Override
      public void run() {
    	  // code here
      }
  }
   
  // Run the thread
  new Example().start();

• Create a class that implements Runnable. We are forced to override run(). This has less restrictions than extending a class since we can implement as many interfaces as we want in Java.

  class Example implements Runnable {
      @Override
      public void run() {
    	  // code here
      }
  }
   
  // Run the thread
  new Thread(new Example()).start();

• Implement Runnable as a lambda expression.

  Runnable runnable = () -> { /* */ };
  new Thread(runnable).start();