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Post By Admin Last Updated At 2021-02-11
What is Java multithreading?

Java is the most popular programming language having in-built support for Java multithreading or Java threads. An application processing may include many processes whether it can be a single thread process or multiple threads may involve. A thread in Java is a lightweight process with a small unit of processing that allows a program to execute multiple threads at the same time. 

The major benefit of using a single thread in any application is that it minimizes the overheads within the app as it executes. And it also minimizes the application’s maintenance cost.

There are multiple Java threads so that we can use Java multithreading as they are mainly use shared area of memory.

Java multithreading example projects

All we know that Java is also a multithreaded coding language that helps to develop a multi-thread program. 

Java multithreading helps users by saving the memory size to store data and it easily switches context between threads. Thus, Java multithreading is mostly used within animations, video games, etc. 

Moreover, threads in Java are useful to run complex tasks in the background without disturbing the main program. They are helpful in the parallel processing of more than two tasks. Here in this blog, I am going to explore the different types of threads in Java, thread creation, and the uses & benefits.

Java multithreading is based on the Thread class, methods, interface, etc. There are two different methods to create a thread such as the Thread class and the second one is run () method. 

In the first method, we can create a thread by extending a thread class.

This can be understood using the simple syntax below:

public class Main Class extends Thread {

  public void run() {

    System.out.println("Main Class running");

  }

}

The second method to create a thread is through applying the Runnable interface. The following syntax will help you to understand it well.

public class Main Class applies Runnable {

  public void run() {

    System.out.println("Main-Class running");

  }

}

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Multithreading in Java

Multithreading in Java

The following example will explain to you how to build a Multi-thread in Java programming.

Demo test; 

public class MultiThread1 implements Runnable

{

       public static void main(String[] args) {

        Thread multiThread1 = new Thread("Multi1");

        Thread multiThread2 = new Thread("Multi2");

        multiThread1.start();

        multiThread2.start();

        System.out.println("These are names of the threads:");

        System.out.println(multiThread1.getName());

        System.out.println(multiThread2.getName());

    }

    @Override

    public void run() {

    }

 }

By using the multi-java multithreading users may not get blocked. Due to the independence of threads, users can execute different operations. Moreover, with these independent threads, other threads may get affected if any of them meets an exception.

Types of Java multithreading

Let us understand what are the different types of Java multithreading in this section.

There are majorly two types of Java multithreading that are available to use. Daemon thread and User threads. 

The Daemon threads in Java are of low-priority as they only offer support to the User Threads. Moreover, these threads in Java serves the User threads while they are running. In this regard, Daemon threads don’t stop the JVM from exiting even the User threads have completed tasks.

Hence, the infinite loops will not cause any issues that generally exist with these threads. Thus, these Java threads are of less importance for I/O tasks.

On the other hand, User threads within Java are the high-priority threads that use JVM. In this section, the JVM waits for the user thread to finish its tasks before it is terminated. 

Here, the Daemon threads are much useful for different tasks such as garbage collection, clearing cache by deleting unnecessary entries, memory cleaning, etc. 

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Thread methods in Java

There are multiple thread methods in Java multithreading which we can see in the following points.

void start()

This command starts the thread in an individual execution path, then solicits the run() method.

void run()

This is useful to perform an action for a thread through the Runnable interface.

Void setName(String)

This command changes the Thread object name or returns a thread. There is another method getName() for recovering the name.

void setPriority(int)

This thread sets or changes the priority of the Thread object.

void setDaemon(boolean on)

This thread is a parameter of true. It denotes that this Thread is a daemon thread.

void join()

This function waits for another thread to die. The existing thread cites this method on a second thread. This is due to the existing thread blocking until the second thread terminates.

void interrupt()

This action puts a hold on this thread. It makes it to continue performance if it was blocked for any reason.

sleep()

This action stops the thread for a specified amount of time or makes it sleep for some time.

Static currentThread

The action returns a reference to the exiting thread object that executes.

getPriority()

Returns the thread priority. 

getID()

Returns thread’s Identity.

Boolean isAlive()

It tests whether the thread is still alive or dead.

void Suspend()

This is useful to suspend any thread from the execution.

void Stop()

Useful to stop the thread from execution for some time.

int activeCount()

This method returns the active number of threads within the existing thread group.

void checkAccess()

This method decides whether the existing running thread has modification permissions.

getState()

The getState method returns the thread’s state. 

Other than the above, there are many other methods available for threading.

Life cycle of thread in Java

The Java runtime system depends upon multiple threads that minimize the inefficiency by preventing CPU waste. Hence, Java threads’ life cycle has five different states. Such as - New, Runnable, Suspended, Blocked, and Terminated. Let us elaborate on them in detail.

New - This is the state when a user creates an instance in the Thread class but before the execution of the start method.

Runnable - The state runnable mentions that the thread is in running state currently.

Suspended - To suspend the thread activity temporarily, the Suspended state is used. Moreover, this thread can start the action again allowing it to execute from its last stop.

Blocked - Here, the existing thread can be easily blocked while it waits for a resource.

Terminated - using this a thread can be terminated any time that halts execution. Also, when the run method is there, we can terminate it. 

Hence, these are the states that Java multithreading has to follow in its lifecycle. This lifecycle is very small in comparison to other programs and services. 

Multithreading in Java- Synchronization

While we begin two or more threads within the Java program, there may be a condition when several threads try to access the same resource. Finally, they can generate accidental output because of concurrency problems. 

These problems arise due to the threads run in parallel with other parts of the program. So, there is no way to know the order of running of a thread. It is also unpredictable when the threads and the main program reads and writes the same variable. 

Hence, there is a need for synchronization of the action of different threads. Also, need to make sure that only a single thread can access the resource at a given time. Moreover, this is applied using a concept called “monitors”. In this, each object within this program is related to a monitor, which a thread can block or unblock. Further, only a single thread can hold a block on a monitor.

The Java coding language offers the easiest way of building threads and synchronizing their task by using sync blocks. 

Advantages of Java multithreading

Using multithreading in Java will be beneficial for the programs in many ways. In this,  Java multithreading. it enables the performance of different parts of the program at the same time. These parts are nothing but the Java threads. Hence, the Java multithreading leads to the complete utilization of the CPU through the multitasking method. 

Multitasking is nothing but the execution of different tasks at the same time. This is achieved in two distinct ways within the Java threads.

Process-based multitasking or Multiprocessing

Thread-based multitasking or Multithreading.

The first one is a heavyweight process where each process carries an in-memory address. Thus, each memory distributes an individual memory area. Also, the communication through this process is very high. Moreover, it takes much time to switch from one process to another performing different tasks. 

The other one is multithreading and it is the lightweight process as we discussed in the above section of the blog. Moreover, this process reduces the cost of communication between the threads in Java. 

Further to achieve the thread programming, Java language offers many Thread Classes too.

There are some other benefits of the Java multithreading process which are as follows.

Resource Sharing

This is nothing but sharing various resources of threads such as memory, data, files, etc. A single app can have multiple threads under the same address space using the resource sharing process.

Responsiveness

The responsiveness of a program allows it to run even if a thread is blocked using a multithreading process. This is also useful when the process is executing a very lengthy operation. For example - A web browser with thread-based multitasking can use a single thread for user contact. And another thread for image loading in parallel.

Utilization of Multiprocessor Architecture

Within a multiprocessor architecture, each thread can run on multiple processors at the same time using this process. This process enhances the concurrency of the device. Also, this is in direct opposition to a single processor system, where only a single thread can run on a processor in parallel.

Economy

Java multithreading is more economical to use as they share the process resources well. Relatively, this is more expensive and takes much time to build processes as they need more memory and resources. Here, the overhead for process building and management is much higher than building a thread and its management.

Thus, these are a few of the advantages of multithreading in Java programs.

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Thread Scheduler - Java multithreading

The thread scheduler within Java programming is part of the JVM. This scheduler decides which thread should run at the given time. Hence, there is no guarantee of choosing a runnable thread by the thread scheduler to run.

In this case, online a single thread at a time can run within a single process. Thus, the thread scheduler mainly uses preemptive scheduling or time-slicing scheduling to organize the threads.

The preemptive schedule says, the highest priority work performs till it enters the waiting or into dead states. It also waits for a higher priority task to come into appearance. Under time slicing scheduling, a job performs for a predefined time slice and again enters the pool of ready jobs.

Conclusion

I hope you got the main idea of Java multithreading and its types, processes, advantages of using, etc. These threads are the parts with a lightweight process that allows the execution of multiple threads in a program. This is also useful to run a background program without interrupting other programs. Moreover, it is the best process to save the memory or it takes less memory area under processing. To learn more about the Java multithreading and its practical usage, go through the Core Java Online Training program with the ITGuru platform. This learning may help you to get skilled in using Java threads for different purposes within the IT industry.