public class Test {

	
		
		public int j = 0;

		public static void main(String[] args) {
			Test lx = new Test();
			Add add = lx.new Add();//例項化成員內部類
			Sub sub = lx.new Sub();
			
			
			for (int i = 0; i < 2; i++) {//考察面向物件
				Thread t = new Thread(add);
				t.start();
				t = new Thread(sub);
				t.start();
			}
		}
		
		public synchronized void add(){//執行緒安全
			j++;
			System.out.println("加法運算："+j);
		}
		
		public synchronized void sub(){
			j--;
			System.out.println("減法運算："+j);
		}
		
		class Add implements Runnable{//內部類的使用

			@Override
			public void run() {
				add();
			}
			
		}
		
		
		class Sub implements Runnable{

			@Override
			public void run() {
				sub();
			}
			
		}
		
	}