Method calling in java using multi threading

Question

While writing a program using multi threading we had a method containing run method in different threads. They used thread.start instead of thread.run. Could someone explain what's the reason behind not calling the method by its name?

This is not an answer to your question but I would suggest you to manage threads with `Executors` https://docs.oracle.com/javase/tutorial/essential/concurrency/executors.html — Radek, Mar 19 '15 at 15:06
This seems to be answered here, have a look: [http://stackoverflow.com/questions/8579657/java-whats-the-difference-between-thread-start-and-runnable-run](http://stackoverflow.com/questions/8579657/java-whats-the-difference-between-thread-start-and-runnable-run) — peter_the_oak, Mar 19 '15 at 16:32

score 0 · Answer 1 · edited May 23 '17 at 12:22

0

The method Thread.run() would execute the method in the current or main thread. Whereas the method Thread.start() would execute the logic in a separate thread.

More Information What's the difference between Thread start() and Runnable run()

edited May 23 '17 at 12:22

Community

1
1

answered Mar 19 '15 at 15:03

Ved Agarwal

565
3
6
14

score 0 · Answer 2 · answered Mar 19 '15 at 15:03

If you call the run() method directly on your class, it will execute the code in the main thread. When you use the Thread.start() method a new thread is created. The JVM then calls your run() method when the thread is allowed to run.

Have a look at the Oracle documentation for this.

score 0 · Answer 3 · answered Mar 19 '15 at 15:15

0

Thread.start() creates a new thread and calls runnable parallelly where as Thread.run() works as just a method call.i.e, no thread is created,So we mostly use Thread.start()

answered Mar 19 '15 at 15:15

user3647410

11
3

score 0 · Answer 4 · answered Mar 19 '15 at 15:25

Thread.start will create a new thread from the current running code and call Thread.run function.
Thread.run will call this class's run method without creating a new thread.

Thread.java:

public synchronized void start() {
    /**
     * This method is not invoked for the main method thread or "system"
     * group threads created/set up by the VM. Any new functionality added
     * to this method in the future may have to also be added to the VM.
     *
     * A zero status value corresponds to state "NEW".
     */
    if (threadStatus != 0 || this != me)
        throw new IllegalThreadStateException();
    group.add(this);
    start0();
    if (stopBeforeStart) {
        stop0(throwableFromStop);
    }
}
public void run() {
    if (target != null) {
        target.run();
    }
}

JDK Thread class: http://hg.openjdk.java.net/jdk6/jdk6/jdk/file/5672a2be515a/src/share/classes/java/lang/Thread.java

Method calling in java using multi threading

4 Answers4