Question

很抱歉在错误的论坛发帖.. 请参阅：https://codereview.stackexchange.com/questions/63055/next-departure-in-java

您好我正在尝试根据Java中的当前系统时间计算下一次出发的时间。

我到目前为止还不熟悉Java的许多方面，但我已经设法让程序在大多数用例中使用switch语句和while循环，但感觉我使用了太多的变通方法来获取代码按预期工作。

下一步是我试图以一种不那么乏味和更优雅的方式完成任务。我想知道是否有人能指出我的方向如何以类似的方式完成任务，但具有java的其他功能？如arraylists，table等适合我想要完成的事情。

以下是代码：

public class TrainDepartures{

public static void main(String[] args) {

    long time = System.currentTimeMillis();
    int initialTime = (int) (time / (1000 * 60) % 60);
    int findNextDeparture = (int) (time / (1000 * 60) % 60);

    boolean foundDeparture = false;

    loop: while (foundDeparture != true) {
        findNextDeparture++;
        switch (findNextDeparture) {
            case 10:
                 System.out.print("Departure in " + (Math.abs(initialTime - 10)) + " min.");
                break loop;
            case 20:
                System.out.print("Departure in " + (Math.abs(initialTime - 20)) + " min.");     
                break loop;
            case 30:
                System.out.print("Departure in " + (Math.abs(initialTime - 30)) + " min.");     
                break loop;
            case 40:
                System.out.print("Departure in " + (Math.abs(initialTime - 40)) + " min.");     
                break loop;
            case 50:
                System.out.print("Departure in " + (Math.abs(initialTime - 50)) + " min.");     
                break loop;
            case 52:
                System.out.print("Departure in " + (Math.abs(initialTime - 52)) + " min.");     
                break loop;
            case 55:
                System.out.print("Departure in " + (Math.abs(initialTime - 55)) + " min.");     
                break loop;
            case 56:
                System.out.print("Departure in " + (Math.abs(initialTime - 56)) + " min.");     
                break loop;
            case 57:
                System.out.print("Departure in " + (Math.abs(initialTime - 57)) + " min.");     
                break loop;         
}
}
}   

}

Answer 1

您可以使用

替换整个switch语句

System.out.print("Departure in " + (Math.abs(initialTime - findNextDeparture)) + " min.");

您以完全相同的方式处理每个案例，因此您不需要switch的复杂性或详细程度。

（例如，如果findNextDeparture==53以及您尚未列出的任何其他值，则假设您还要打印该行。）

Answer 2

以下是您可以尝试的内容。使用String格式更改switch语句：

    final int departureTime = Math.abs(initialTime - findNextDeparture);
    String result = String.format("Departure in %d min", departureTime);
    System.out.print(result);

Switch语句的输出和上面的代码是一样的。

Answer 3

public class TrainDepartures
{
    public static void main(String[] args)
    {
        long time = System.currentTimeMillis();
        int initialTime = (int) (time / (1000 * 60) % 60);
        //these are the minutes you care about.
        int[] departureTimes = new int[]{10,20,30,40,50,52,55,56,57};
        int lastValidId = 0;
        int timeDiff = 0;

        for (int d = 0; d < departureTimes.length; d++)
        {
            if ( initialTime < departureTimes[d])
            {
                //keep track of the smallest value greater than the current time.
                lastValidId = d;
                timeDiff = (departureTimes[lastValidId] - initialTime);
                if (d == 0)//first time, were done.
                    break;
            }
            else
            {
                timeDiff = (departureTimes[lastValidId] - initialTime);
                if ( timeDiff < 0 )
                {
                    //wrap around when you cross into the next hour...
                    timeDiff = (departureTimes[0]+60) - initialTime;            
                }
                break;
            }
        }       
        System.out.print("Departure in " + timeDiff + " min.");
    }   
}

下一次离开Java

3 个答案: