public class Main {
public static void main(String[] args) {
        Test test = new Test();
        ThreadA threadA = new ThreadA();
        ThreadB threadB = new ThreadB();

        threadA.setTest(test);
        threadB.setTest(test);

        threadA.start();
        threadB.start();

        System.out.println(threadA.getTest());
        System.out.println(threadB.getTest());
     }
}

class Test {
private int num;

public synchronized int getNum() {
return this.num;
    }

public synchronized void setNum(int num) {
this.num = num;
    }
}

class ThreadA extends Thread{
private Test test;

public void setTest(Test test ) {
this.test = test;
    }

public int getTest() {
        System.out.println("ThreadA getTest() 실행됨");
return test.getNum();
    }

@Override
    public void run() {
test.setNum(1120);
        System.out.println("ThreadA run 실행됨 : " + test.getNum());
    }

}

class ThreadB extends Thread{
private Test test;

public void setTest(Test test) {
this.test = test;
    }

public int getTest() {
        System.out.println("ThreadB getTest() 실행됨");
return test.getNum();
    }

@Override
    public void run() {
test.setNum(1120);
        System.out.println("ThreadB run 실행됨 : " + test.getNum());
    }
}