设计java一个程序，能够让多个用户同时从4个销售点完成100张票的购票操作

这个问题涉及到并发编程，可以通过使用多线程来现多个用户同时购票。

首先，需要定义一个Ticket类，用于表示票的信息，包括票号和销售点编号等。

public class Ticket {
    private int id;
    private int salesPoint;

    public Ticket(int id, int salesPoint) {
        this.id = id;
        this.salesPoint = salesPoint;
    }

    public int getId() {
        return id;
    }

    public int getSalesPoint() {
        return salesPoint;
    }

    @Override
    public String toString() {
        return "Ticket{" +
                "id=" + id +
                ", salesPoint=" + salesPoint +
                '}';
    }
}

然后，我们定义一个TicketBox类，用于表示所有的票，并提供购票和获取票的方法。

import java.util.ArrayList;
import java.util.List;

public class TicketBox {
    private List<Ticket> tickets;

    public TicketBox(int count) {
        tickets = new ArrayList<>();
        for (int i = 1; i <= count; i++) {
            tickets.add(new Ticket(i, 0));
        }
    }

    public synchronized Ticket buyTicket(int salesPoint) {
        for (Ticket ticket : tickets) {
            if (ticket.getSalesPoint() == 0) {
                ticket = new Ticket(ticket.getId(), salesPoint);
                return ticket;
            }
        }
        return null;
    }

    public synchronized List<Ticket> getTickets() {
        return tickets;
    }
}

在购票的方法中，我们需要使用synchronized关键字来保证多个用户不会同时购买同一张票。

接下来，我们定义一个SalesPoint类，用于表示一个销售点，提供购票和获取已售票的方法。

import java.util.List;

public class SalesPoint {
    private int id;
    private TicketBox ticketBox;

    public SalesPoint(int id, int ticketCount) {
        this.id = id;
        ticketBox = new TicketBox(ticketCount);
    }

    public Ticket buyTicket() {
        return ticketBox.buyTicket(id);
    }

    public List<Ticket> getSoldTickets() {
        List<Ticket> tickets = ticketBox.getTickets();
        tickets.removeIf(ticket -> ticket.getSalesPoint() != id);
        return tickets;
    }
}

最后，我们定义一个Main类，模拟多个用户同时购票的过程。

public class Main {
    public static void main(String[] args) {
        int salesPointCount = 4;
        int ticketCount = 100;
        SalesPoint[] salesPoints = new SalesPoint[salesPointCount];
        for (int i = 0; i < salesPointCount; i++) {
            salesPoints[i] = new SalesPoint(i + 1, ticketCount / salesPointCount);
        }

        Thread[] threads = new Thread[ticketCount];
        for (int i = 0; i < ticketCount; i++) {
            int salesPointIndex = i % salesPointCount;
            Thread thread = new Thread(() -> {
                Ticket ticket = salesPoints[salesPointIndex].buyTicket();
                System.out.println("User " + Thread.currentThread().getId() + " bought ticket: " + ticket);
            });
            thread.start();
            threads[i] = thread;
        }

        for (Thread thread : threads) {
            try {
                thread.join();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

        for (int i = 0; i < salesPointCount; i++) {
            System.out.println("Sales point " + (i + 1) + " sold tickets: " + salesPoints[i].getSoldTickets());
        }
    }
}

在Main类中，我们首先创建4个销售点，每个销售点拥有25张票。然后，我们创建100个线程模拟100个用户同时购票的过程。每个线程选择一个销售点进行购票，购票成功后打印出票的信息。最后，我们输出每个销售点已售出的票的信息。

这样，我们就完成了一个能够让多个用户同时从4个销售点完成100张票的购票操作的Java程序。