/**
 * 模拟考试，时间为120分钟，学生可以再30分钟后交卷，
 * 当学生都交完了 或 时间到者考试结束
 */
class Student implements Runnable,Delayed{
	private String name;
	private long submitTime;//交卷时间
	private long workTime;//考试时间
	public Student(String name, long submitTime) {
		this.name = name;
		workTime = submitTime;
		//都转为转为ns
		this.submitTime = TimeUnit.NANOSECONDS.convert(submitTime, TimeUnit.MILLISECONDS) + System.nanoTime();
	}
	public void run() {
		System.out.println(name + " 交卷,用时" + workTime/100 + "分钟");
	}
	public long getDelay(TimeUnit unit) {
		return unit.convert(submitTime - System.nanoTime(), TimeUnit.NANOSECONDS);
	}
	public int compareTo(Delayed o) {
		Student that = (Student) o;
		return submitTime > that.submitTime?1:(submitTime < that.submitTime ? -1 : 0);
	}
	public static class EndExam extends Student{
		private ExecutorService exec;
		public EndExam(int submitTime,ExecutorService exec) {
			super(null,submitTime);
			this.exec = exec;
		}
		public void run() {
			exec.shutdownNow();
		}
	}
}
class Teacher implements Runnable{
	private DelayQueue<Student> students;
	
	public Teacher(DelayQueue<Student> students) {
		this.students = students;
	}
	public void run() {
		try {
			System.out.println("考试开始……");
			while (!Thread.interrupted()) {
				students.take().run();
			}
			System.out.println("考试结束……");
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
	}
}
public class Exam {
	static final int STUDENT_SIZE = 45;
	public static void main(String[] args) {
		Random r = new Random();
		DelayQueue<Student> students = new DelayQueue<Student>();
		ExecutorService exec = Executors.newCachedThreadPool();
		for(int i = 0; i < STUDENT_SIZE; i++){
			students.put(new Student("学生" + i, 3000 + r.nextInt(9000)));
		}
		students.put(new Student.EndExam(12000,exec));//1200为考试结束时间
		exec.execute(new Teacher(students));
	}
}