What are Threads in Java?

• You can think of a thread as a sub-process that operates independently and concurrently with other threads within a larger process.
•  For each thread, it is a small and lightweight unit of processing.
• Thread is a class defined in Java. Lang package is implicitly inherited in all the user-defined and predefined classes in Java.

Key Points:

• Thread class specifies three main properties i.e. ID, name, and priority.
• Thread class has overloaded constructors.
• We can create Thread in two ways.

 1. By extending the Thread class:

Example:

package quipoin;
class Demo extends Thread {
	public void run() {
		System.out.println("Thread is running!!");
	}

	public static void main(String args[]) {
		Demo t1 = new Demo();
		t1.start();
	}
}

Output:

Thread is running!!

 2. By implementing Runnable interface: Runnable Interface is present in the java .lang package and it has only one method public void run().

Example:

package quipoin;
class Sample implements Runnable {
	public void run() {
		System.out.println("Thread is running!!");
	}

	public static void main(String args[]) {
		Sample m1 = new Sample();
		Thread t1 = new Thread(m1); // Using the constructor Thread(Runnable r)
		t1.start();
	}
}

Output:

Thread is running!!

Thread Properties:

1. Thread Id:

•   It is a unique integer number that is used to identify thread class instances created in JVM.
• Thread Id is initialized at the time of object creation automatically. We cannot change the Id of a Thread.

2. Thread Name:

• It is a String type used to set the name of a thread.
• For every thread created in JVM default name is initialized user can provide the name of a thread and can change it.

3. Thread Priority:

• Thread priority is a number that is used to define the priority of a thread.
• JVM executes the thread based on the thread priority.
• The priority ranges from 1(low priority) to 10(high priority).
• If the user is not defining the priority of a thread then the default priority is 5(mid).