写2个线程,其中一个线程打印1~52,另一个线程打印A~z,打印顺序应该是12A34B45C……5152Z

我写的

class LN
{
    private int flag = 0;
    public static char ch = 'A';
    public static int n = 1;
    public synchronized void printLetter()
    {
        try
        {
            if(flag == 0 || flag == 1)
            {
                wait();
            }
            else
            {
                //System.out.println("flag = " +     flag);
                System.out.print(ch);
                ch++;
 
                flag = (flag + 1) % 3;
 
                notifyAll();
            }
        }
        catch(InterruptedException ex)
        {
            ex.printStackTrace();
        }
    }
    public synchronized void printNumber()
    {
        try
        {
            if(flag == 2 )
            {
                wait();
            }
            else
            {
                //System.out.println("flag = " +     flag);
                System.out.print(n);
                n++;        
 
                flag = (flag + 1) % 3;
 
                notifyAll();
            }
        }
        catch(InterruptedException ex)
        {
            ex.printStackTrace();
        }
    }
}
 
class Letter extends Thread
{
    LN ln;
    Letter(LN ln)
    {
        this.ln = ln;
    }
    public void run()
    {
        for(int i = 0 ; i< 26; i++)
        {
            ln.printLetter();
        }
    }
}
class Number extends Thread
{
    LN ln;
    Number(LN ln)
    {
        this.ln = ln;
    }
    public void run()
    {
        for(int i = 0 ; i< 78; i++)
        {
            ln.printNumber();
        }
    }
}
 
class Practice1
{
    public static void main(String[] args) {
 
        LN ln = new LN();
        new Letter(ln).start();
        new Number(ln).start();
    }
}

网上找的

public class ThreadDemo {
// 测试
public static void main(String[] args) {
Object obj = new Object();
// 启动两个线程
Thread1 t1 = new Thread1(obj);
Thread2 t2 = new Thread2(obj);
 
t1.start();
t2.start();
}
}
 
class Thread1 extends Thread {
private Object obj;
 
public Thread1(Object obj) {
this.obj = obj;
}
 
public void run() {
// 加锁
synchronized (obj) {
// 打印1-52
for (int i = 1; i < 53; i++) {
System.out.print(i);
if (i % 2 == 0) {
// 不能忘了唤醒其它线程
obj.notifyAll();
try {
obj.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
 
}
}
}
 
class Thread2 extends Thread {
private Object obj;
 
public Thread2(Object obj) {
this.obj = obj;
}
 
public void run() {
synchronized (obj) {
// 打印A-Z
for (int i = 0; i < 26; i++) {
System.out.print((char) ('A' + i));
// 不能忘了唤醒其它线程
obj.notifyAll();
try {
obj.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}