Java编程,打印昨天的当前时刻

import java.util.Calendar; import java.util.Date; public class YesterdayCurrent extends Thread { private static int id = 0; private static int number = 10; private Object obj; public static void main(String[] args) { Object object = new Object(); YesterdayCurrent thread; for (int i = 0; i < 5; i++) { thread = new YesterdayCurrent(object); } } public YesterdayCurrent(Object obj) { super("" + ++id); this.obj = obj; start(); } public String toString() { return "THREAD#" + getName(); } private Date getDate() { Calendar calendar = Calendar.getInstance(); calendar.add(Calendar.MONTH, 0); calendar.add(Calendar.DATE, -1); Date date = calendar.getTime(); return date; } public void run() { synchronized (obj) { StringBuffer buffer; while (number <= 100) { buffer = new StringBuffer(toString()); buffer.append("\t昨天是:"); buffer.append(getDate().getMonth()); buffer.append("月"); buffer.append(getDate().getDate()); buffer.append("日"); System.out.println(buffer); number += 10; obj.notifyAll(); //一定要有这个判断，否则线程阻塞 if (number <= 100) { try { obj.wait(); sleep(100); } catch (Exception e) { e.printStackTrace(); } } } } } }