Java thread programming tutorial pdf

Here only class 1 is having the run method to make the thread transcend from runnable to tun state to execute whereas thread 2 is only created but not put to run state by the scheduler as its corresponding run method was missing. Hence, only thread 1 is called rest thread 2 is created only and is in the runnable state later blocked by scheduler because the corresponding run method was missing.

Here as we have seen in the above example in way 1 where Thread class is extended. Here Runnable interface being a functional interface has its own run method. Here classes are implemented to the Runnable interface. Later on, in the main method, Runnable reference is created for the classes that are implemented in order to make bondage between with Thread class to run our own corresponding run methods.

Further, while creating an object of Thread class we will pass these references in Thread class as its constructor allows an only runnable object, which is passed as a parameter while creating Thread class object in a main method. Now lastly just likely what we did in Thread class, start method is invoked over the runnable object who are now already linked with Thread class objects, so the execution begins for our run methods in case of Runnable interface.

Extending the class Implementing the interface which is runnable Make sure to create an object of threads in which you have to pass the object of runnable Special Methods of Threads Now let us discuss there are various methods been there for threads.

Here we will be discussing out major ones in order to have a practical understanding of threads and multithreading which are sequential as follows: start Method suspend Method stop Method wait Method notify Method notifyAll Method sleep Method Output Without sleep Method Output with sleep method in Serial Execution Processes Blocking methods approach Output with sleep method in Parallel Execution Processes Unblocking methods approach join Method Note: For naive users in multithreading where threads are backbone go through Program 4 to get very basics of threads, how to start, make it hold, or terminate then only toggle to program 1 and rest as follows.

The default priority is set to 5 as excepted. Minimum priority is set to 0. Maximum priority is set to Here we will be using the knowledge gathered above as follows: We will use currentThread method to get the name of the current thread. It is because the default priority of running thread as soon as the corresponding start method is called is executed as per setting priorities for all the thread to 5 which is equivalent to the priority of NORM case.

This is because both the outputs are equivalent to each other. While in case 3 priority is set to a minimum on a scale of 1 to 10 so do the same in case 4 where priority is assigned to 10 on the same scale. Hence, all the outputs in terms of priorities are justified. Now let us move ahead onto an important aspect of priority threading been incorporated in daily life is Daemon thread Daemon thread is basically a service provider thread that provides services to the user thread.

As soon as the user thread is terminated daemon thread is also terminated at the same time as being the service provider thread. Hence, the characteristics of the Daemon thread are as follows: It is only the service provider thread not responsible for interpretation in user threads. So, it is a low-priority thread. It is a dependent thread as it has no existence on its own. Yes, you guess the most popular example is garbage collector in java.

Exceptions: IllegalArgumentException as return type while setting a Daemon thread is boolean so do apply carefully. Note: To get rid of the exception users thread should only start after setting it to daemon thread.

The other way of starting prior setting it to daemon will not work as it will pop-out IllegalArgumentException As discussed above in the Thread class two most widely used method is as follows: Daemon Thread Methods Action Performed isDaemon It checks whether the current thread is a daemon thread or not setDaemon It set the thread to be marked as daemon thread Let us discuss the implementation of the Daemon thread before jumping onto the garbage collector.

Here main method in itself is a thread because of which you do see Exception in main while running the program because of which system. Synchronization It is the mechanism that bounds the access of multiple threads to share a common resource hence is suggested to be useful where only one thread at a time is granted the access to run over.

For more depth in synchronization, one can also learn object level lock and class level lock and do notice the differences between two to get a fair understanding of the same before implementing the same. Why synchronization is required? Data inconsistency issues are the primary issue where multiple threads are accessing the common memory which sometimes results in faults in order to avoid that a thread is overlooked by another thread if it fails out.

Data integrity To work with a common shared resource which is very essential in the real world such as in banking systems. Note: Do not go for synchronized keyword unless it is most needed, remember this as there is no priority setup for threads, so if the main thread runs before or after other thread the output of the program would be different. The biggest advantage of synchronization is the increase in idiotic resistance as one can not choose arbitrarily an object to lock on as a result string literal can not be locked or be the content.

Hence, these bad practices are not possible to perform on synchronized method block. As we have seen humongous advantages and get to know how important it is but there comes disadvantage with it. Disadvantage: Performance issues will arise as during the execution of one thread all the other threads are put to a blocking state and do note they are not in waiting state.

This causes a performance drop if the time taken for one thread is too long. As perceived from the image in which we are getting that count variable being shared resource is updating randomly. It is because of multithreading for which this concept becomes a necessity. We have run it many times and compiled and run once again wherein all cases here main thread is executing faster than created thread but do remember output may vary.

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React Native. Python Design Patterns. Python Pillow. Python Turtle. Verbal Ability. Interview Questions. Company Questions. Artificial Intelligence. Cloud Computing. Data Science. Angular 7. Machine Learning. Data Structures. Operating System. Computer Network. Compiler Design. Computer Organization. The problems that result from this are called concurrency problems. To avoid concurrency problems, it is best to share as few attributes between threads as possible.

If attributes need to be shared, one possible solution is to use the isAlive method of the thread to check whether the thread has finished running before using any attributes that the thread can change. We just launched W3Schools videos. Get certified by completing a course today! If you want to report an error, or if you want to make a suggestion, do not hesitate to send us an e-mail:. Differences between "extending" and "implementing" Threads The major difference is that when a class extends the Thread class, you cannot extend any other class, but by implementing the Runnable interface, it is possible to extend from another class as well, like: class MyClass extends OtherClass implements Runnable.

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