No.1编写一个打印机类

写两个方法

 1 public class Printer {
 2 
 3     public void print1()
 4     {
 5         
 6             System.out.print("微");
 7             System.out.print("冷");
 8             System.out.print("的");
 9             System.out.print("雨");
10             System.out.println();
11     }
12     public void print2()
13     {
14         
15             System.out.print("好");
16             System.out.print("人");
17             System.out.println();
18         
19         
20     }
21 }

目的：为了使两个线程执行该类中的两个方法

线程一：

public class MyThread extends Thread {
    public static Printer p1;
@Override
public void run() {
    for (int i = 1; i <=500; i++) {
        p1.print1();
    }
}

线程二：

public class MyThread2 implements Runnable{
    public static Printer p2;
    @Override
    public void run() {
       for (int i = 1; i <=500; i++) {
            p2.print2();
        }
    }

}

Test类中的方法调用

public class Test {
public static void main(String[] args) {
    Printer p=new Printer();
    MyThread t1=new MyThread();
    t1.p1=p;
    t1.start();
    MyThread2 t2=new MyThread2();
    t2.p2=p;
    Thread t3=new Thread(t2);
    t3.start();
    
}
}

则会出现以下情况：因为程序员不能手动干预cpu分配线程资源

解决方法：加上同步锁，使当一个线程执行完之后另一个线程才有执行的权利 

public class Printer {

    public void print1()
    {
        synchronized (this) {
            System.out.print("微");
            System.out.print("冷");
            System.out.print("的");
            System.out.print("雨");
            System.out.println();
        }
        
    }
    public void print2()
    {
        synchronized (this) {
            System.out.print("好");
            System.out.print("人");
            System.out.println();
        }
        
    }
}

解决完毕！！！！！！！！！