Difference Betwixt Showtime Together With Function Method Inwards Thread – Coffee Tutorial Together With Interview Question

Why create i telephone band start method of thread if start() calls run() inwards turn" or "What is departure past times calling start() over run() method inwards coffee thread" are 2 widely popular beginner aeroplane multi-threading interview question. When a Java programmer start learning Thread, commencement affair he learns is to implement thread either overriding run() method of Thread aeroplane or implementing Runnable interface in addition to than calling start() method on thread, but amongst to a greater extent than or less sense he finds that start() method calls run() method internally either past times looking API documentation or precisely poking around, but many of us precisely don’t attention at that fourth dimension until its been asked inwards Java Interview. In this Java tutorial nosotros volition run across What is departure betwixt calling start() method in addition to run() method for starting Thread inwards Java.

This article is inwards continuation of my before post service on Java multi-threading e.g. Difference betwixt Runnable in addition to Thread inwards Java in addition to How to solve Producer Consumer work inwards Java using BlockingQueue. If yous haven’t read them already yous may uncovering them interesting in addition to useful.

Difference betwixt start in addition to run inwards Java Thread

programming mistake because caller has intention of calling start() to create novel thread in addition to this error tin endure uncovering past times many static code coverage tools similar findbugs. If yous desire to perform fourth dimension consuming delineate of piece of work than ever telephone band start() method otherwise your main thread volition stuck piece performing fourth dimension consuming delineate of piece of work if yous telephone band run() method directly. Another departure betwixt start vs run inwards Java thread is that yous can non telephone band start() method twice on thread object. i time started, minute telephone band of start() volition throw IllegalStateException in Java piece yous tin telephone band run() method twice.

Code Example of start vs run method

Here is a unproblematic code illustration which prints refer of Thread which executes run() method of Runnable task. Its clear that if yous telephone band start() method a novel Thread executes Runnable delineate of piece of work piece if yous direct telephone band run() method task, electrical flow thread which is original inwards this instance volition execute the task.

public class StartVsRunCall{

    public static void main(String args[]) {
       
        //creating 2 threads for start in addition to run method call
        Thread startThread = new Thread(new Task("start"));
        Thread runThread = new Thread(new Task("run"));
       
        startThread.start(); //calling start method of Thread - volition execute inwards novel Thread
        runThread.run();  //calling run method of Thread - volition execute inwards electrical flow Thread

    }

    /*
     * Simple Runnable implementation
     */
    private static class Task implements Runnable{
        private String caller;
       
        public Task(String caller){
            this.caller = caller;
        }
       
        @Override
        public void run() {
            System.out.println("Caller: "+ caller + " in addition to code on this Thread is executed past times : " + Thread.currentThread().getName());
           
        }        
    }
}

Output:

Caller: start in addition to code on this Thread is executed past times : Thread-0
Caller: run in addition to code on this Thread is executed past times : main

In Summary alone difference betwixt start() in addition to run() method inwards Thread is that start creates novel thread piece run doesn't create whatever thread in addition to merely execute inwards electrical flow thread similar a normal method call.

Further Learning
Multithreading in addition to Parallel Computing inwards Java
Java Concurrency inwards Practice - The Book
How to Stop Thread inwards Java

Difference betwixt ConcurrentHashMap in addition to Hashtable inwards Java

Why hold off in addition to notify methods are declared inwards Object Class?

Why hold off in addition to notify needs to called from Synchronized Context?

Difference betwixt invokeAndWait in addition to InvokeLater inwards coffee Swing.

Difference betwixt hold off in addition to slumber inwards Java

How to write Thread Safe Class inwards Java

How to create Race weather inwards Java amongst Example
Difference betwixt Daemon in addition to non Daemon Thread inwards Java