如何在 Java 中定义基于两个变量进行比较的比较器

Question

我想创建一个比较器来操作，以便具有较低到达时间的进程将首先出现在排序中，如果两个进程具有相同的到达时间，则具有较低进程 id 的进程首先出现在排序中。我尝试了以下代码，但似乎不起作用。有没有人看到它的缺陷？

public class FCFSComparator implements Comparator<Process>
{
    public int compare(Process o1, Process o2)
    {
        int result = o1.getArrivalTime() - o2.getArrivalTime();

        if(result == 0)
        {
            return (o1.getPid() < o2.getPid()) ? -1 : 1;
        }
        else
        {
            return result;
        }
//        return (result != 0 ? result : o1.getPid() - o2.getPid());
    }
}

具体来说，给定过程如下

pid = 0 arrival time = 10
pid = 1 arrival time = 30
pid = 2 arrival time = 15
pid = 3 arrival time = 15
pid = 4 arrival time = 66

我在最后得到以下顺序

Pid = 0 arrival time = 10
Pid = 2 arrival time = 15
Pid = 1 arrival time = 30
Pid = 4 arrival time = 66
Pid = 3 arrival time = 15

Answer 1

我找不到你的比较器有什么问题。这是我的测试用例：

public class TestComparator {

    static class Process {
        int pid;
        int arrivalTime;

        Process(int pid, int arrivalTime) {
            this.pid = pid;
            this.arrivalTime = arrivalTime;
        }

        @Override
        public String toString() {
            return "Process [pid=" + pid + ", arrivalTime=" + arrivalTime + "]";
        }
    }

    static class FCFSComparator implements Comparator<Process> {
        public int compare(Process o1, Process o2) {
            int result = o1.arrivalTime - o2.arrivalTime;

            if (result == 0) {
                return (o1.pid < o2.pid) ? -1 : 1;
            } else {
                return result;
            }
        }
    }

    public static void main(String[] args) {
        List<Process> processes = Arrays.asList(
                new Process(0, 10),
                new Process(1, 30),
                new Process(2, 15),
                new Process(3, 15),
                new Process(4, 66));

        Collections.sort(processes, new FCFSComparator());

        for (Process process : processes) {
            System.out.println(process);
        }

    }
}

输出：

Process [pid=0, arrivalTime=10]
Process [pid=2, arrivalTime=15]
Process [pid=3, arrivalTime=15]
Process [pid=1, arrivalTime=30]
Process [pid=4, arrivalTime=66]