Multithreading (multi-threading)

Creating Threads in Java

Things to does to the create threads in Java:

(1) Create a task (object)

Creating a task

public class Taskclass implements Runnable {

Public Taskclass () {...}

Implement the Run method in Runnable

　　void Run () {

Things to does in the task}

}

Runnable interface

Public interface Runnable {

void run ();

}

(2) Create a thread and combine the task with the thread (object)

1 by

Create a task class

public class Taskclass implements Runnable {

Public Taskclass (...) { ... }

Implement the Run method in Runnable

void Run () {

Things to does in the task

}

}

public class threaddemo{

public void SomeMethod () {

Create an instance of Taskclass

Taskclass Task=new taskclass (...);

Create a thread

　　　　Thread thread=new thread (Task);

Start a thread

　　　　Thread.Start ();

}

}

　2 by

Custom Thread Class

public class Customthread extends Thread {

Public Customthread () {...}

Override the Run method in Runnable

void Run () {

Things to does in the task

}

}

public class threaddemo{

public void SomeMethod () {

Create a thread

Customthread thread1=new customthread ();

Start a thread

　　　　Thread1.start ();

Create another thread

Customthread thread2=new Customthread ();

Start a thread

Thread2.start ();

}

　　}

Main Thread

When a program starts, the main Thread automatically starts

The default name of the Thread:main with priority 5

public static void Main (string[] args) {

System.out.println ("Current thread:" + Thread.CurrentThread ());

　　　　Thread.CurrentThread (). SetName ("MyThread");

System.out.println ("After name change:" + Thread.CurrentThread ());

}

Example: Create Threads

public class ThreadDemo1 {

public static void Main (string[] args) {

String hw= "do home Work";

String tv= "Watch TV";

DoSomething dohw= New dosomething (HW);

DoSomething Watchtv = new dosomething (TV);

}

}

　　

public class DoSomething {

Private String Dowhat;

Public dosomething (String athing) {

This.dowhat = athing;

DoIt ();

}

public void DoIt () {

for (int i=0;i<5;i++)

System.out.println (dowhat+ ":" +i);

}

}

does not use multithreading

Create Threads (Solution 1)

public class ThreadDemo1 {

public static void Main (string[] args) {

DoSomething dohw= New DoSomething ("Do home Work");

DoSomething Watchtv = new DoSomething ("Watch TV");

Thread hwthread= new Thread (DOHW);

Thread tvthread = new Thread (WATCHTV);

　　　　　　Hwthread.start ();

　　　　　　Tvthread.start ();

}

}

public class DoSomething implements Runnable {

Private String Dowhat;

Public dosomething (String athing) {

This.dowhat = athing;

} public void Run () {

for (int i=0;i<5;i++)

System.out.println (dowhat+ ":" +i);

}

}

Create Threads Solution 2

public class ThreadDemo2 extends Thread {

String dothing;

ThreadDemo2 (String dowhat) {

This.dothing=dowhat;

}

public static void Main (string[] args) {

String hw= "do home Work";

String tv= "Watch TV";

　　　　ThreadDemo2 thread1=new ThreadDemo2 (HW);

　　　　ThreadDemo2 thread2=new THREADDEMO2 (TV);

　　　　Thread1.start ();

　　　　Thread2.start ();

}

　　public void Run () {

　　　　for (int i=0;i<5;i++)

　　　　　　System.out.println (dothing+ ":" +i);

　　　　}

　　}

Control a Thread

public static void Yield ():

Causes the currently executing thread object to temporarily pause

Allow and threads to execute (execute)

　　　　Athread.yield ();

T1.yield ();

T2.sleep (1000);

static void sleep (Long Millis):

Causes the currently executing thread to sleep (block) for the specified number of milliseconds

If the thread is blocked by sleep or wait, an interruptedexception is thrown

try {

Athread.sleep (1000);

Sleep for 1 second

} catch (Interruptedexception ex) {

Do sth ...

}

　　Interrupt ():

Does not stop a thread Set ' interrupted ' status to true why interrupt?

　　After interrupt are set, we can take actions

　　Isinterrupted ():

Tests Whether this thread has been interrupted.

The interrupted status of the thread is unaffected by this method.

if (isinterrupted ()) {

Action

}

　　Interrupted ():

　　Tests whether the current thread has been interrupted.

The interrupted status of the thread is cleared by this method.

Returns:true if the current thread has been interrupted; False otherwise.

public class ThreadDemo2 extends Thread {

String dothing;

ThreadDemo2 (String dowhat) {

This.dothing=dowhat;

}

public static void Main (string[] args) {

String hw= "do home Work";

String tv= "Watch TV";

ThreadDemo2 thread1=new ThreadDemo2 (HW);

ThreadDemo2 thread2=new THREADDEMO2 (TV);

Thread1.start ();

Thread2.start ();

}

public void Run () {

for (int i=0;i<5;i++) {

System.out.println (dothing+ ":" +i);

　　　　　　This.yield ();

}

}

}

public class ThreadDemo2 extends Thread {

String dothing;

ThreadDemo2 (String dowhat) {

This.dothing=dowhat;

}

public static void Main (string[] args) {

String hw= "do home Work";

String tv= "Watch TV";

ThreadDemo2 thread1=new ThreadDemo2 (HW);

ThreadDemo2 thread2=new THREADDEMO2 (TV);

Thread1.start ();

Thread2.start ();

}

public void Run () {

for (int i=0;i<5;i++) {

System.out.println (dothing+ ":" +i);

　　　　try {

　　　　　　This.sleep (10);

　　　　　　} catch (Interruptedexception ex) {

　　　　　　System.out.println ("sth wrong");

　　　　　　}

}

}

}

Synchronization

Both or more threads share the same resource Synchronized method:

To make a method synchronized:add the Synchronized keyword to its declaration

When the one thread is executing a synchronized method for a object, all and threads that invoke synchronized methods for T He same object block (suspend execution) until the first thread is do with the object

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Multithreading (multi-threading)