Introduction to concurrent programming (I)

Introduction to concurrent programming （ One ）

Why do I have to be concurrent ？

Improve resource utilization , Speed up the program .

Java Memory model ：

The working memory ： private Each thread allocates independent memory , Mutual interference

Main memory ： All processes share

Thread class [implements Runnable]

There are three ways to create a thread ：

1. Inherit Thread class , rewrite run Method , example .start perform

   public class ThreadExtendTest extends Thread{
         
       @Override
       public void run(){
         
           System.out.println("thread success");
       }
       public static  void main(String []args){
         
           new ThreadExtendTest().start();
       }
   
   }
   

2. Realization Runnable Interface , rewrite run Method ,Thread example .start perform

   public class ThreadExtendTest implements Runnable{
       @Override
       public void run(){
           System.out.println("thread success");
       }
       public static  void main(String []args){
           new Thread(new ThreadExtendTest()).start();
       }
   
   

3. Realization Callable Interface , rewrite call Method , establish FutureTask Get the return value .

   public class ThreadCallableTest implements Callable<String>{
   
       @Override
       public String call(){
           return "you are right";
       }
   
       public static void main(String[] args) throws ExecutionException, InterruptedException {
          FutureTask<String> futureTask = new FutureTask<>(new ThreadCallableTest());
          Thread thread = new Thread(futureTask);
          thread.start();
          System.out.println(futureTask.get());
   
       }
   
   }
   

   Anonymous inner class Realization Runnable Simple version of interface

   public class Test {
         
       public static void main(String[] args) {
         
           Thread t = new Thread(new Runnable() {
         
               @Override
               public void run() {
         
                   System.out.println("you area success");
               }
           });
           t.start();
       }
   }
   

   Thread Methods

   run() // Specific operations to be performed 
   start() // perform  run()  Method 
   sleep() // Sleep  n  millisecond 
   getName() // Get the thread name 
   setName() // Modify the thread name