写两个线程，一个线程打印1-52，了，另一个线程打印A-Z，要求打印顺序为12A34B56C…5152Z。（线程同步加等待唤醒的协作机制）

练习多线程时发现几种方式，记录一下：

第一种：加判断条件然后用++i

public class Test {
    public static void main(String[] args) {
        Count obj = new Count();
        new Thread(() -> {
            synchronized (obj) {
                for (int i = 1; i <= 52; i++) {
                    System.out.println(i);
                    if (obj.getCount() == 0) {
                        System.out.println(++i);
                        try {
                            obj.wait();
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                    obj.setCount(0);
                    obj.notify();
                }
            }
        }).start();
        new Thread(() -> {
            synchronized (obj) {
                for (int i = 'A'; i <= 'Z'; i++) {
                    if (obj.getCount() == 2) {
                        try {
                            obj.wait();
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                    System.out.println((char) i);
                    obj.setCount(2);
                    obj.notify();
                }
            }
        }).start();
    }
}

class Count {
    private int count;

    public int getCount() {
        return count;
    }

    public void setCount(int count) {
        this.count = count;
    }
}

第二种：和第一种大同小异，加一个i%2判断是否为零

public class PrintNum {
    public static void main(String[] args) {
        Count obj = new Count();
        new Thread(() -> {
            synchronized (obj) {
                for (int i = 1; i < 53; i++) {
                    System.out.println(i);
                    if (i % 2 == 0) {
                        try {
                            obj.wait();
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                    obj.notify();
                }
            }
        }).start();
        new Thread(() -> {
            synchronized (obj) {
                for (int i = 'A'; i <= 'Z'; i++) {
                    if (obj.getCount() != 0) {
                        try {
                            obj.wait();
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                    System.out.println((char) i);
                    obj.setCount(1);
                    obj.notify();
                }
            }
        }).start();
    }
}
class Count{
    private int count;

    public int getCount() {
        return count;
    }

    public void setCount(int count) {
        this.count = count;
    }
}

第三种：则是调用方法

class Print{
    private int flag = 1;
    private int count = 1;

    public synchronized void printNum(){
        while(flag != 1) {
            //此时应该打印字母
            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){
            //此时应该打印数字
            try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        System.out.print((char)(count-1+'A'));
        //继续前行
        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();
    }
}

第三种方法来自main--的博客

写两个线程，一个线程打印 1~ 52，另一个线程打印A~Z， 打印顺序是12A34B...5152Z；main--的博客https://blog.youkuaiyun.com/qq_41420688/article/details/84334894