Java 多线程

import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.concurrent.TimeUnit;

public class SoldTicket {

    public static List<String> list = new ArrayList<String>();
    public static int counter = 1;
    public static Random random = new Random();

    public static void main(String[] args) {
        initTickets();
        SoldTicket st = new SoldTicket();
        for (int i = 1; i <= 5; i++) {
            st.new Solder().start();
        }
    }

    private synchronized String getOneTicket() {
        if (list.size() <= 0)
            return null;
        return list.remove(0);
    }

    private static void initTickets() {
        for (int i = 1; i <= 100; i++) {
            list.add("第 " + i + " 张票");
        }
    }

    class Solder extends Thread {
        public final int id = counter++;

        public Solder() {
            this.setName("售票窗口" + id);
        }

        @Override
        public void run() {
            while (!this.isInterrupted()) {
                String ticket = getOneTicket();
                if (ticket == null) {
                    System.out.println(this.getName() + ":票已售空，明天请早");
                    break;
                }
                System.out.println(this.getName() + " 卖出了 " + ticket);
                try {
                    TimeUnit.MILLISECONDS.sleep(random.nextInt(500));
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}