学习JAVA第十九天

Posted 2021-08-21 N1ghtMare

java中的线程

线程：程序中单个顺序的流程控制

2.线程体

run方法来实现

3.创建线程的两种方法

*继承Thread类创建线程

public class TestThread1 { 
 public static void main(String args[]){
  Thread t = new MyThread(100);
  t.start();
 }
}

class MyThread extends Thread {
 private int n;;
 public MyThread( int n ){
  super();
  this.n=n;
 }
 public void run() {
  for(int i=0;i<n;i++) {
   System.out.print (" " + i);
  }
 }
}

*通过向Thread构造方法传递Runnable对象创建线程

public class TestThread2 {
 public static void main(String args[]) {
  MyTask mytask = new MyTask(10);
  Thread thread = new Thread(mytask);
  thread.start();
  //thread.setDaemon(true);

  for(int i=0; i<6; i++) { 
   System.out.println("Main--" + i);
   try{
    Thread.sleep(500);
   }catch( InterruptedException e ){}
  }

 }
}

class MyTask implements Runnable {
 private int n;
 public MyTask(int n){
  this.n = n;
 }
 public void run() {
  for(int i=0; i<n; i++) { 
   System.out.println(" " + i);
   try{
    Thread.sleep(500);
   }catch( InterruptedException e ){}
  }
 }
}

4.匿名类和Lambda表达式

可以匿名类来实现Runnable

new Thread{

    public void (){

        for(int i = 0; i<10; i++)

            System.out.println(i);

        }

}.star();

 

也可以用Lambda表达式

public class TestThread4Anonymous {
 public static void main(String args[]) {

  new Thread(){
   public void run() {
    for(int i=0; i<10; i++) 
     System.out.println(i);
   }
  }.start();

  new Thread( ( ) -> {
   for(int i=0; i<10; i++)
    System.out.println(" "+ i);
  } ).start();
 }
}

 

 

多线程：

import java.util.*;
import java.text.*;
public class TestThread3 {
 public static void main(String args[]) {
  Counter c1 = new Counter(1);
  Thread t1 = new Thread(c1);
  Thread t2 = new Thread(c1);
  Thread t3 = new Thread(c1);
  Counter c2 = new Counter(2);
  Thread t4 = new Thread(c2);
  Thread t5 = new Thread(c2);
  Thread t6 = new Thread(c2);
  TimeDisplay timer = new TimeDisplay();
  Thread t7 = new Thread(timer);
  t1.start();
  t2.start();
  t3.start();
  t4.start();
  t5.start();
  t6.start();
  t7.start();
 }
}

class Counter implements Runnable {
 int id;
 Counter(int id){
  this.id = id;
 }
 public void run() {
  int i=0;
  while( i++<=10 ){
   System.out.println("ID: " + id + "  No. " + i);
   try{ Thread.sleep(10); } catch( InterruptedException e ){}
  }
 }
}

class TimeDisplay implements Runnable {
 public void run(){
  int i=0;
  while( i++<=3 ){
   System.out.println(
    new SimpleDateFormat().format( new Date()));
   try{ Thread.sleep(40); } catch( InterruptedException e ){}
  }
 }
}

5.多线程的控制

*基本控制

启动：  start()

结束：  设定一个标记变量，来结束方法

暂时阻止：  try { Thread.sleep(1000); }catch( InterruptedException e) { }

6.后台线程：

*普通线程

非Daemon线程

*Daemon线程

import java.util.*;
public class TestThreadDaemon {
 public static void main(String args[]) {
  Thread t = new MyThread();
  t.setDaemon(true);
  t.start();

  System.out.println( "Main--" + new Date());
  try{ Thread.sleep(500); }
  catch(InterruptedException ex){}
  System.out.println("Main End");
 }
}

class MyThread extends Thread {
 public void run() {
  for(int i=0; i<10; i++ ){
   System.out.println(  i + "--" + new Date());
   try{ Thread.sleep(100); }
   catch(InterruptedException ex){}
  }
 }
}