Life cycle of thread in java

In the following state transition diagram we show the various states for a Java thread and the events that cause the thread to jump from one state to another. Thread States in Java – Understanding Thread Life Cycle of Java Threads As you begin you journey into Java Development there will come a time in your life where you will want to take advantage of multithreading for performance reasons. When you do, you will inevitably need to become familiar with the life cycle of java threads. Constructed/Born A newly created Thread in Java will be in this state just after constructing but before calling the start() method. Thread t1 = new Thread( new BankAccount( 1)); Ready-To-Run We must call the start() method in order to schedule the thread to begin running. It is this that puts a thread into the “Ready to Run” state. When the thread’s run() method is called, the thread goes into “Running” state. t1.start(); Warning Please note, a common mistake of novice programmers is to call the run() method like this, t1.run() We do not call run() method, instead always make sure you start the thread using the start() method. Running Once running, a thread may go back to the “Ready to Run” state when one of the following occurs: Waiting A Running thread will go into a waiting state when an object’s wait() method is called. This mechanism is used as a communication means between threads in order to avoid polling. Waiting threads are put into the object’s queue. When another thread associated ...

Java Threads Threads allows a program to operate more efficiently by doing multiple things at the same time. Threads can be used to perform complicated tasks in the background without interrupting the main program. Creating a Thread There are two ways to create a thread. It can be created by extending the Thread class and overriding its run() method: Extend Example public class Main extends Thread If the class implements the Runnable interface, the thread can be run by passing an instance of the class to a Thread object's constructor and then calling the thread's start() method: Implement Example public class Main implements Runnable 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. Concurrency Problems Because threads run at the same time as other parts of the program, there is no way to know in which order the code will run. When the threads and main program are reading and writing the same variables, the values are unpredictable. The problems that result from this are called concurrency problems. Example A code example where the value of the variable amount is unpredictable: public class Main extends Thread To avoid concurrency problems, it is best to share as few attributes between threads as possible....

2. Runnable: A thread after invocation of start() method will be in runnable state. A thread in runnable state will be available for thread scheduler. 3. Running: A thread in execution after thread scheduler select it, it will be in running state. 4. Blocked: A thread which is alive but not in runnable or running state will be in blocked state. A thread can be in blocked state because of suspend(), sleep(), wait() methods or implicitly by JVM to perform I/O operations. 5. Dead: A thread after exiting from run() method will be in dead state. We can use stop() method to forcefully killed a thread. Next Topic: Multithreading in java. Previous Topic: Commonly used exception methods of Throwable class in java.

In this article, we'll discuss in detail a core concept in Java – the lifecycle of a thread. We'll use a quick illustrated diagram and, of course, practical code snippets to better understand these states during the thread execution. To get started understanding Threads in Java, 2. Multithreading in Java • NEW – a newly created thread that has not yet started the execution • RUNNABLE –either running or ready for execution but it's waiting for resource allocation • BLOCKED –waiting to acquire a monitor lock to enter or re-enter a synchronized block/method • WAITING –waiting for some other thread to perform a particular action without any time limit • TIMED_WAITING –waiting for some other thread to perform a specific action for a specified period • TERMINATED – has completed its execution All these states are covered in the diagram above; let's now discuss each of these in detail. 3.1. New A NEW Thread (or a Born Thread) is a thread that's been created but not yet started. It remains in this state until we start it using the start() method. The following code snippet shows a newly created thread that's in the NEW state: Runnable runnable = new NewState(); Thread t = new Thread(runnable); System.out.println(t.getState()); Since we've not started the mentioned thread, the method t.getState() prints: NEW 3.2. Runnable In a multi-threaded environment, the Thread-Scheduler (which is part of JVM) allocates a fixed amount of time to each thread. So it runs for a particular amount o...

Overview A thread in java is the direction or path taken by the program for its execution. Thread in java helps us to achieve multiprogramming where a program or process can operate more efficiently by executing more than one instruction at a time. A thread in java also helps a complicated or larger task to operate in the background without interrupting the main program. The Thread class and Runnable interface in java help us to create and control a thread in java. What is a Thread in Java? In terms of the Operating System, we can say that a thread is the smallest unit of processing (smallest unit of a process). A thread is an independent path of execution in a program. Thread is a line of execution in a program. A thread in java is the direction or path taken by the program for its execution. Thread in java helps us to achieve multiprogramming where a program or process can operate more efficiently by executing more than one instruction at a time. A thread in java also helps a complicated or larger task to operate in the background without interrupting the main program. Note: • The main method is also known as the main thread of execution. • The JVM or Java Virtual Machine allows an application to execute multiple threads within a program concurrently. • When we start the JVM, a single thread (typically called as main thread) is started by the main() method. Multi-threading is a concept in modern operating systems that refers to two or more tasks executing concurrently wi...

Thread Concept in Java Before introducing the thread concept, we were unable to run more than one task in parallel. It was a drawback, and to remove that drawback, Thread Concept was introduced. A Thread is a very light-weighted process, or we can say the smallest part of the process that allows a program to operate more efficiently by running multiple tasks simultaneously. In order to perform complicated tasks in the background, we used the Thread concept in Java. All the tasks are executed without affecting the main program. In a program or process, all the threads have their own separate path for execution, so each thread of a process is independent. Another benefit of using thread is that if a thread gets an exception or an error at the time of its execution, it doesn't affect the execution of the other threads. All the threads share a common memory and have their own stack, local variables and program counter. When multiple threads are executed in parallel at the same time, this process is known as In a simple way, a Thread is a: • Feature through which we can perform multiple activities within a single process. • Lightweight process. • Series of executed statements. • Nested sequence of method calls. Thread Model Just like a process, a thread exists in several states. These states are as follows: 1) New (Ready to run) A thread is in New when it gets CPU time. 2) Running A thread is in a Running state when it is under execution. 3) Suspended A thread is in the Suspend...

Understanding Thread Life Cycle in Java and Thread States are very important when you are working with Threads and programming for multithreaded environment. From our last tutorial, we can create a Below diagram shows different states of thread life cycle in java. We can create a thread in java and start it but how the thread states change from Runnable to Running to Blocked depends on the OS implementation of thread scheduler and java doesn’t have full control on that. When we create a new Thread object using new operator, thread state is New Thread. At this point, thread is not alive and it’s a state internal to Java programming. When we call start() function on Thread object, it’s state is changed to Runnable. The control is given to Thread scheduler to finish it’s execution. Whether to run this thread instantly or keep it in runnable thread pool before running, depends on the OS implementation of thread scheduler. When thread is executing, it’s state is changed to Running. Thread scheduler picks one of the thread from the runnable thread pool and change it’s state to Running. Then CPU starts executing this thread. A thread can change state to Runnable, Dead or Blocked from running state depends on time slicing, thread completion of run() method or waiting for some resources. A thread can be waiting for other thread to finish using Once the thread finished executing, it’s state is changed to Dead and it’s considered to be not alive. Above are the different states of thr...