线程Synchronized

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public class Demo1_Synchronized {

/** * @param args * 同步代码块 */public static void main(String[] args) {    final Printer p = new Printer();    new Thread() {        public void run() {            while(true) {                p.print1();            }        }    }.start();    new Thread() {        public void run() {            while(true) {                p.print2();            }        }    }.start();}

}

class Printer {
Demo d = new Demo();
public void print1() {
//synchronized(new Demo()) { //同步代码块,锁机制,锁对象可以是任意的
synchronized(d) {
System.out.print(“1”);
System.out.print(“2”);
System.out.print(“3”);
System.out.print(“4”);
System.out.print(“5”);
System.out.print(“\r\n”);
}
}

public void print2() {    //synchronized(new Demo()) {                            //锁对象不能用匿名对象,因为匿名对象不是同一个对象    synchronized(d) {               System.out.print("A");        System.out.print("B");        System.out.print("C");        System.out.print("D");        System.out.print("\r\n");    }}

}

class Demo{}

public class Demo2_Synchronized {

/** * @param args * 同步代码块 */public static void main(String[] args) {    final Printer2 p = new Printer2();    new Thread() {        public void run() {            while(true) {                p.print1();            }        }    }.start();    new Thread() {        public void run() {            while(true) {                p.print2();            }        }    }.start();}

}

class Printer2 {
Demo d = new Demo();
//非静态的同步方法的锁对象是神马?
//答:非静态的同步方法的锁对象是this
//静态的同步方法的锁对象是什么?
//是该类的字节码对象
public static synchronized void print1() { //同步方法只需要在方法上加synchronized关键字即可
System.out.print(“1”);
System.out.print(“2”);
System.out.print(“3”);
System.out.print(“4”);
System.out.print(“5”);
System.out.print(“\r\n”);
}

public static void print2() {    //synchronized(new Demo()) {                            //锁对象不能用匿名对象,因为匿名对象不是同一个对象    synchronized(Printer2.class) {          System.out.print("A");    System.out.print("B");    System.out.print("C");    System.out.print("D");    System.out.print("\r\n");    }}

}

public class Demo3_Ticket {

/** * 需求:铁路售票,一共100张,通过四个窗口卖完. */public static void main(String[] args) {    new Ticket().start();    new Ticket().start();    new Ticket().start();    new Ticket().start();}

}

class Ticket extends Thread {
private static int ticket = 100;
//private static Object obj = new Object(); //如果用引用数据类型成员变量当作锁对象,必须是静态的
public void run() {
while(true) {
synchronized(Ticket.class) {
if(ticket <= 0) {
break;
}
try {
Thread.sleep(10); //线程1睡,线程2睡,线程3睡,线程4睡
} catch (InterruptedException e) {

                e.printStackTrace();            }            System.out.println(getName() + "...这是第" + ticket-- + "号票");        }    }}

}

public class Demo4_Ticket {

/** * @param args * 火车站卖票的例子用实现Runnable接口 */public static void main(String[] args) {    MyTicket mt = new MyTicket();    new Thread(mt).start();    new Thread(mt).start();    new Thread(mt).start();    new Thread(mt).start();    /*Thread t1 = new Thread(mt);               //多次启动一个线程是非法的    t1.start();    t1.start();    t1.start();    t1.start();*/}

}

class MyTicket implements Runnable {
private int tickets = 100;
@Override
public void run() {
while(true) {
synchronized(this) {
if(tickets <= 0) {
break;
}
try {
Thread.sleep(10); //线程1睡,线程2睡,线程3睡,线程4睡
} catch (InterruptedException e) {

                e.printStackTrace();            }            System.out.println(Thread.currentThread().getName() + "...这是第" + tickets-- + "号票");        }    }}

}

public class Demo5_DeadLock {

/** * @param args */private static String s1 = "筷子左";private static String s2 = "筷子右";public static void main(String[] args) {    new Thread() {        public void run() {            while(true) {                synchronized(s1) {                    System.out.println(getName() + "...获取" + s1 + "等待" + s2);                    synchronized(s2) {                        System.out.println(getName() + "...拿到" + s2 + "开吃");                    }                }            }        }    }.start();    new Thread() {        public void run() {            while(true) {                synchronized(s2) {                    System.out.println(getName() + "...获取" + s2 + "等待" + s1);                    synchronized(s1) {                        System.out.println(getName() + "...拿到" + s1 + "开吃");                    }                }            }        }    }.start();}

}

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