Multi-threading enables you to write in a way where multiple activities can proceed concurrently in the same program.
A thread goes through various stages in its life cycle. For example, a thread is born, started, runs, and then dies.
The following diagram shows the complete life cycle of a thread. It remains in this state until the program starts the thread. It is also referred to as a born thread. A thread in this state is considered to be executing its task.
A thread transitions back to the runnable state only when another thread signals the waiting thread to continue executing. A thread in this state transitions back to the runnable state when that time interval expires or when the event it is waiting for occurs.
Every Java thread has a priority that helps the operating system determine the order in which threads are scheduled. Threads with higher priority are more important to a program and should be allocated processor time before lower-priority threads. However, thread priorities cannot guarantee the order in which threads execute and are very much platform dependent.
If your class is intended to be executed as a thread then you can achieve this by implementing a Runnable interface. As a first step, you need to implement a run method provided by a Runnable interface.
This method provides an entry point for the thread and you will put your complete business logic inside this method. We create an object of our new class and call start method to start the execution of a thread. Start invokes the run method on the Thread object. Thread creation by implementing the Runnable Interface We create a new class which implements java.
Here's a brief introduction to Java Thread concepts that many people find tricky like multithreading and concurrency. There are two ways to create a thread in java. First one is by Let's see the examples of creating a thread. 1) Java Thread Example by extending Thread class.
Runnable interface and override run method. Then we instantiate a Thread object and call start method on this object.
Thread Class vs Runnable Interface 1. But, if we implement the Runnable interface, our class can still extend other base classes. We can achieve basic functionality of a thread by extending Thread class because it provides some inbuilt methods like yield , interrupt etc.
The first thread will run in the first core, and the second thread will run in the second core. For example in a web browser, if everything ran in a single Thread, then system will be completely unresponsive whenever data is being fetched to display. If it takes 10 seconds to fetch the data, then in that 10 seconds we wont be able to do anything else in the web browser like opening new tabs, or even closing the web browser. So running different parts of a program in different threads concurrently helps improve the responsiveness of a system. We will look at Callables and the Executor Framework in a separate Blog.
In order to create a Piece of code which can be run in a Thread, we create a class and then extend the Thread class.
The task being done by this piece of code needs to be put in the run function. In the below code you can see that Worker is a class which extends Thread Class, and the task of printing numbers 0 to 5 is being done inside the run function. In the Above code Thread.
In order to create a Thread , we just need to create an instance of the Worker class. And then we can start the Thread using the start function. In the Above code, we are creating 3 threads t1,t2 and t3 from the Worker class. Then we are starting the threads using the start function. It can be seen clearly from the output that the 3 threads do not run in any particular sequence. In order to create a Piece of code which can be run in a Thread, we create a class and then implement the Runnable Interface.
In the below code you can see that RunnableWorker is a class which implements Runnable Interface, and the task of printing numbers 0 to 4 is being done inside the run function.
What is a Static Keyword in Java? I also discuss Thread 's debugging aids and user threads versus daemon threads. Java assigns the name main to the thread that runs the main method, the starting thread. When multiple threads execute, one thread's path through the same code usually differs from the others. In this article, I introduce you to Java threads and runnables.