java线程面试题2

设计4个线程，其中两个线程每次对j增加1，另外两个线程对j每次减少1。写出程序。

 

public static void main(String[] args) {
  // new InterviewQuestionTest().init();
  new InterviewQuestionTest().init2();
 }

 private void init2() {
  final Business2 business = new Business2();
  for (int i = 0; i < 2; i++) {
   new Thread() {
    public void run() {
     business.increament();
    }
   }.start();

   new Thread() {
    public void run() {
     business.decreament();
    }
   }.start();
  }
 }

 class Business2 {
  int j = 0;

  public synchronized void increament() {
   System.out.println(Thread.currentThread().getName() + " increament: " + j++);
  }

  public synchronized void decreament() {
   System.out.println(Thread.currentThread().getName() + " decreament: " + j--);
  }
 }