多线程练习题

末蓝、 2022-04-11 12:15 197阅读 0赞

### 问题1 ###

写两个线程，一个线程打印1-52，另一个线程打印A-Z；  
打印顺序为：12A34B56C…5152Z

class Print{
        private int flag = 1;
        private int count = 1;
    
        public synchronized void printNum() {
            while (flag != 1) {
                //应该打印字母
                try {
                    wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            System.out.print(2 * count-1);
            System.out.print(2 * count);
            flag = 2;
            notify();
        }
    
        public synchronized void printChar() {
            while (flag != 2) {
                //应该打印数字
                try {
                    wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.print((char) (count-1 + 'A'));
                count++;
                flag = 1;
                notify();
            }
        }
    }
    
    public class Test {
        public static void main(String[] args) {
            Print print = new Print();
            new Thread(()->{
                for(int i = 0;i<26;i++){
                    print.printNum();
                }
            }).start();
            new Thread(()->{
                for(int i = 0;i<26;i++){
                    print.printChar();
                }
            }).start();
        }
    }

### 问题2 ###

编写一个程序，启动三个线程，三个线程的名称分别是A,B,C；每个线程将自己的名称在屏幕上打印5遍；  
打印顺序为：ABCABCABCABCABC

class Print {
        private int flag = 1;
        private int count = 0;
    
        public int getCount() {
            return count;
        }
    
        public synchronized  void printA(){
            while(flag!=1) {
                try {
                    wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            System.out.print(Thread.currentThread().getName());
            count++;
            flag = 2;
            notifyAll();
        }
        public synchronized  void printB(){
            while(flag != 2){
                try {
                    wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            System.out.print(Thread.currentThread().getName());
            flag = 3;
            count++;
            notifyAll();
        }
        public synchronized  void printC(){
            while(flag != 3){
                try {
                    wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            System.out.print(Thread.currentThread().getName());
            flag = 1;
            count++;
            notifyAll();
        }
    }
    class MyThread implements Runnable{
        private Print print;
        public MyThread(Print print){
            this.print = print;
        }
        @Override
        public void run() {
            while(print.getCount()<16){
                if(Thread.currentThread().getName().equals("A")){
                    print.printA();
                }else if(Thread.currentThread().getName().equals("B")){
                    print.printB();
                }else if(Thread.currentThread().getName().equals("C")){
                    print.printC();
                }
            }
    
        }
    }
    
    public class Test {
        public static void main(String[] args) {
            Print print = new Print();
            MyThread mt = new MyThread(print);
            Thread thread1 = new Thread(mt,"A");
            Thread thread2 = new Thread(mt,"B");
            Thread thread3 = new Thread(mt,"C");
            thread1.start();
            thread2.start();
            thread3.start();
        }
    }