每次发送通知，只能通知到其中一个线程，多个线程必须多次发出通知。

		
package cn.netkiller.test;

public class Test {
    static Object object = new Object();

    public static void main(String[] args) {
        Test test = new Test();
        new Thread(() -> {
            synchronized (object) {
                System.out.println("开始线程 A");
                try {
                    object.wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("结束线程 A");
            }
        }, "线程 A").start();


        new Thread(() -> {
            try {
                Thread.sleep(500L);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            synchronized (object) {
                System.out.println("开始线程 B");
                try {
                    object.wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("结束线程 B");
            }
        }, "线程 B").start();


        new Thread(() -> {
            try {
                Thread.sleep(3000L);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            synchronized (object) {
                System.out.println("开始通知线程 C");
                object.notify();
                object.notify();
                System.out.println("结束通知线程 C");
            }
        }, "线程 C").start();

    }

}		
		
			

notifyAll() 一次通知所有线程

		
        new Thread(() -> {
            try {
                Thread.sleep(3000L);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            synchronized (object) {
                System.out.println("开始通知线程 C");
                object.notifyAll();
                System.out.println("结束通知线程 C");
            }
        }, "线程 C").start();		
		
			

			
package cn.netkiller.test;

import lombok.Data;

public class Test {
    private static final Message object = new Message();

    public static void main(String[] args) {
        Test test = new Test();
        new Thread(() -> {
            synchronized (object) {
                System.out.println("开始线程 A");
                try {
                    object.wait();
                    System.out.println(Thread.currentThread().getName() + ": " + object.getText());
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("结束线程 A");
            }
        }, "线程 A").start();


        new Thread(() -> {
            try {
                Thread.sleep(500L);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            synchronized (object) {
                System.out.println("开始线程 B");
                try {
                    object.wait();
                    System.out.println(Thread.currentThread().getName() + ": " + object.getText());
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("结束线程 B");
            }
        }, "线程 B").start();


        new Thread(() -> {
            try {
                Thread.sleep(3000L);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            synchronized (object) {
                System.out.println("开始通知线程 C");
                object.setText("https:/www.netkiller.cn");
                object.notifyAll();
                System.out.println("结束通知线程 C");
            }
        }, "线程 C").start();

    }

    @Data
    public static class Message {
        private String text;
    }

}