package tst.thread;public class InputOutput {    public static void main(String[] args) {        Res r = new Res();                                                      new Thread(new Input(r)).start();        new Thread(new Output(r)).start();    }}class Input implements Runnable {    Res r;    public Input(Res r) {        this.r = r;    }                                              public void run() {        int x = 0;        while(true) {            if(x == 0) {                r.setInfo("小明", "男");            } else {                r.setInfo("小红", "女");            }            x = (x + 1) % 2;        }    }}class Output implements Runnable {    Res r;    public Output(Res r) {        this.r = r;    }                                              public void run() {        while(true) {            r.showInfo();        }    }}class Res {    private String name;    private String sex;    boolean flag = false;                                              public synchronized void setInfo(String name,String sex) {        if(flag) {            try {                this.wait();            } catch (InterruptedException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }        }        this.name = name;        this.sex = sex;        flag = true;        this.notify();    }                                              public synchronized void showInfo() {        if(!flag) {            try {                this.wait();            } catch (InterruptedException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }        }        System.out.println("The name is " + this.name + ",the sex is " + this.sex);        flag = false;        this.notify();    }}

当多线程是多个写入，多个读取，若按上述操作则可能出现所有线程同时等待。这时判断flag应该为while，而不用if，并改notify()为notifyall()！下为例子：

package tst.thread;public class ProCon {    public static void main(String[] args) {        Resource r = new Resource();                  Pro p1 = new Pro(r);        Pro p2 = new Pro(r);        Cons p3 = new Cons(r);        Cons p4 = new Cons(r);                  Thread t1 = new Thread(p1);        Thread t2 = new Thread(p2);        Thread t3 = new Thread(p3);        Thread t4 = new Thread(p4);                  t1.start();        t2.start();        t3.start();        t4.start();    }}class Resource {    private String proname = "Product--";    private int count = 0;    private boolean flag = false;          public synchronized void pro() {        while(flag) {            try {                wait();            } catch (InterruptedException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }        }        System.out.println(Thread.currentThread().getName() + "==" + proname + "生产---" + ++count);        flag = true;        this.notifyAll();    }          public synchronized void con() {        while(!flag) {            try {                wait();            } catch (InterruptedException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }        }        System.out.println(Thread.currentThread().getName() + "==" + proname + "消费------" + count);        flag = false;        this.notifyAll();    }}class Pro implements Runnable {    Resource r;    public Pro(Resource r) {        this.r = r;    }    public void run() {        while(true) {            r.pro();        }    }      }class Cons implements Runnable {    Resource r;    public Cons(Resource r) {        this.r = r;    }    public void run() {        while(true) {            r.con();        }    }}