详解Java多线程编程中的线程同步方法

class MyThread3 implements Runnable{

 //两个线程操作同一个对象，共享成员变量
 //int i;
 @Override
 public void run() {
  //两个线程操作同一个对象，各自保存局部变量的拷贝
  int i = 0;
  while(i<100){
   System.out.println(i);
   i++;
   try {
    Thread.sleep(100);
   } catch (InterruptedException e) {
    e.printStackTrace();
   }
  }
 }
}

public static void main(String[] args) {

 MyThread3 myThread = new MyThread3();
 //下面两个线程对同一个对象(Runnable的实现类对象)进行操作
 Thread thread = new Thread(myThread);
 Thread thread2 = new Thread(myThread);
 //各自保存局部变量的拷贝，互不影响，输出200个数字
 thread.start();
 thread2.start();
}

class Number{
 private int number = 10;
 public String getNumber(int i){
  if(number > 0){
   try {
    Thread.sleep(100);
   } catch (InterruptedException e) {
    e.printStackTrace();
   }
   number -= i;
   return "取出"+i+"成功，剩余数量："+number;
  }
  return "取出"+i+"失败，剩余数量："+number;
 }
}

class MyThread4 extends Thread{

 //两个线程操作同一个对象，共享成员变量
 Number number;
 public MyThread4(Number number){
  this.number = number;
 }
 @Override
 public void run() {
  System.out.println(number.getNumber(8));
 }
}

public static void main(String[] args) {

 Number number = new Number();
 //两个线程操作同一个对象，共享对象number的成员变量number
 MyThread4 myThread = new MyThread4(number);
 MyThread4 myThread2 = new MyThread4(number);
 myThread.start();
 myThread2.start();
}

/**
 * 定义一个类，包含了线程类需要调用的方法
 */
class Compute1{
 //这时如果某个线程调用该方法，
 //将锁定synchronized方法所在对象对应的class对象，
 //而不是锁定synchronized方法所在对象
 public synchronized static void execute(){
  for(int i = 0; i<100; i++){
   try {
    Thread.sleep(100);
   } catch (InterruptedException e) {
    e.printStackTrace();
   }
   System.out.println("compute1:execute1 " + i++);
  }
 }
 public synchronized static void execute2(){
  for(int i = 0; i<100; i++){
   try {
    Thread.sleep(100);
   } catch (InterruptedException e) {
    e.printStackTrace();
   }
   System.out.println("compute1:execute2 " + i++);
  }
 }
}

public static void main(String[] args) {
 Compute1 com = new Compute1();
 Thread thread1 = new Thread1(com);
 Thread thread2 = new Thread2(com);
 thread1.start();
 thread2.start();
}

/**
 * 定义一个类，包含了线程类需要调用的方法
 */
class Compute1{
 //通过同步代码块锁定object1对象进行锁定了其他同样的synchronized代码块
 private Object object1 = new Object();
 public void execute(){
  synchronized(object1){
   for(int i = 0; i<100; i++){
    try {
     Thread.sleep(100);
    } catch (InterruptedException e) {
     e.printStackTrace();
    }
    System.out.println("compute1:execute1 " + i++);
   }
  }

 }
 public synchronized void execute2(){
  synchronized(object1){
   for(int i = 0; i<100; i++){
    try {
     Thread.sleep(100);
    } catch (InterruptedException e) {
     e.printStackTrace();
    }
    System.out.println("compute1:execute2 " + i++);
   }
  }
 }
}

synchronized(this){
 …
}