Java wait() notify()循环打印A和B

线程中不应该有else，把else注释掉就正确了。 如果加上else后，该线程会在wait后不再notify，导致另一个线程无限wait。

public class Test {
    
    public static Object object = new Object();
    public static boolean printA = true;
    
    public static void main(String[] args) {
        ThreadA threadA = new ThreadA();
        threadA.start();
        
        ThreadB threadB = new ThreadB();
        threadB.start();
    }
}
 
class ThreadA extends Thread {
    
    @Override
    public void run() {
        for(int i = 0; i < 10; i++) {
            synchronized (Test.object) {
                if(!Test.printA) {
                    try {
                        Test.object.wait();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }/* else {*/
                    System.out.println("A");
                    Test.printA = false;
                    Test.object.notify();
                /*}*/
            }
        }
    }
}

class ThreadB extends Thread {
    
    @Override
    public void run() {
        for(int i = 0; i < 10; i++) {
            synchronized (Test.object) {
                if(Test.printA) {
                    try {
                        Test.object.wait();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }/* else { */
                    System.out.println("B");
                    Test.printA = true;
                    Test.object.notify();
                /*}*/
            }
        }
    }
}