Question

import java.util.*;

public class elevator_EXPERIMENT {
    public static void main(String[] args) {

        ArrayList<Integer> UpArrayList = new ArrayList<Integer>();
        ArrayList<Integer> DownArrayList = new ArrayList<Integer>();

        int[] Floor = new int[12];
        for (int i = 0; i < Floor.length; i++) {
            Floor[i] = i + 1;
        }
        while (UpArrayList.size() != 8) {
            if (Math.random() > 0.5) {
                Random x = new Random();
                int UpRandom = (x.nextInt(11 - 1) + 1) + 1;
                Random x1 = new Random();
                int UpRandom1 = (x1.nextInt(11 - 1) + 1) + 1;
                if (UpRandom != UpRandom1 && !UpArrayList.contains(Floor[UpRandom])) {
                    UpArrayList.add(UpRandom1);
                }
            }
        }
        while (UpArrayList.size() != 8) {
            Random x = new Random();
            int UpRandom = (x.nextInt(11 - 1) + 1) + 1;
            while (UpArrayList.contains(Floor[UpRandom])) {

            }
        }
        System.out.print("Unsorted floors going up ");
        for (int i = 0; i < UpArrayList.size(); i++) {
            System.out.print(UpArrayList.get(i) + " ");
        }
        System.out.println();
        while (DownArrayList.size() != 5) {
            if (Math.random() > 0.5) {
                Random y = new Random();
                int DownRandom = (y.nextInt(11 - 1) + 1) + 1;
                if (DownArrayList.contains(Floor[DownRandom])) {
                    Random y1 = new Random();
                    int DownRandom1 = (y1.nextInt(11 - 1) + 1) + 1;
                    if (DownRandom != DownRandom1 && !DownArrayList.contains(Floor[DownRandom1])) {
                        DownArrayList.add(DownRandom1);
                    }
                } else {
                    DownArrayList.add(Floor[DownRandom]);
                }
            }
        }
        System.out.print("\nUnsorted floors going down ");
        for (int i = 0; i < DownArrayList.size(); i++) {
            System.out.print(DownArrayList.get(i) + " ");
        }
        Collections.sort(UpArrayList);
        System.out.print("\n\n" + "Sorted floors going up ");
        for (int i = 0; i < UpArrayList.size(); i++) {
            System.out.print(UpArrayList.get(i) + " ");
        }
        Collections.sort(DownArrayList, Collections.reverseOrder());
        System.out.print("\n\n" + "Sorted floors going down ");
        for (int i = 0; i < DownArrayList.size(); i++) {
            System.out.print(DownArrayList.get(i) + " ");
        }
        System.out.println();
        for (int i = 0; i < 8; i++) {
            int floornumber = 1;
            System.out.println("\nStarting at floor " + floornumber);
            floornumber++;
            System.out.println("Going up: now at floor " + UpArrayList.get(floornumber));
            System.out.println("Stopping at floor " + UpArrayList.get(floornumber) + " for 3 seconds -> 1,2,3");
            SleepTimer(3000);
        }
    }

    public static void SleepTimer(int time) {
        try {
            Thread.sleep(time);
        } catch (Exception e) {
            System.out.println("Something went wrong");
        }
    }
}

您好，请查看SleepTimer方法上方的for循环。我有两个问题。我的目标是创建一个电梯txt模拟器，电梯有12层。我创建了两个Arraylists：一个包含8个随机唯一的楼层，另一个包含5个随机唯一的楼层，分别标记为UpArrayList和DownArrayList。然后我对它们进行排序然后我应该创建一个类似于这样的txt提示符：

2 3 4 6 7 8 10 11 Sorted ArrayList

        Starting at floor 1
        Going up: now at floor 2
    Stopping at floor 2 for 3 seconds  1, 2, 3 

    Starting at floor 2 
        Going up: now at floor 3
    Stopping at floor 3 for 3 seconds  1, 2, 3

    Starting at floor 3 
        Going up: now at floor 4
    Stopping at floor 4 for 3 seconds  1, 2, 3

    Starting at floor 4 
        Going up: now at floor 5
        Going up: now at floor 6
     Stopping at floor 6 for 3 seconds  1, 2, 3

     Starting at floor 6
         Going up: now at floor 7
    Stopping at floor 7 for 3 seconds  1, 2, 3

     Starting at floor 7
         Going up: now at floor 8                                                                            
     Stopping at floor 8 for 3 seconds  1, 2, 3

基本上我想要for循环中提示的格式（在程序结束时）说

Starting at Floor1
Going up: now at floor[FirstElementofUpArrayList]
Stopping at floor[FirstElementofUpArrayList" for 3 seconds -> 1,2,3
Starting at floor[SecondElementofUpArrayList]
Going up: now at floor[SecondElementofUpArrayList] for 3 seconds -> 1,2,3

直到我到达UpArrayList的最后一个元素。

Answer 1

“ArrayList在forloop中的行为不符合预期”

它什么都没说，但看看你的实现我猜你的问题是java.lang.IndexOutOfBoundsException它是因为你的列表大小是8而元素是从0到7的索引。最后一个循环的最后一次迭代是调用UpArrayList.get（8），但没有第9个元素。变化

UpArrayList.get(floornumber);

到

UpArrayList.get(i);

在for循环中，ArrayList的行为不符合预期

1 个答案: