Question

我创建了4种Pod类：

Kitchen Pod
Hygiene Pod
睡觉荚
Social Pod

每个Pod都有他们可以接受的限制（厨房限制= 8，卫生限制= 2，睡眠限制= 2，社会限制= 10）。当达到限制时，我必须创建另一个相同类型的Pod来存储剩余部分。我有ArrayList将Pod个对象存储在名为SpaceStationTester的其他类中。我试图将特定容量（人数）设置为每种Pod中的第一种（通过调用每个Pod类中的容量设置器方法）而不会弄乱其他类型（假设我有更多比一个“厨房”，“睡觉”等的豆荚......）

但相反，我最终设置了所有厨房，睡眠，社交和卫生容器的新容量。

我怎样才能设置各种容量？这是我的SpaceStation课程：

public class SpaceStationTester {
    public static void main(String[] args) {
        /* Step 1: Create space station that will support 15 colonists.
                   Report the configuration of all pods created. 
        */
        SpaceStation station = new SpaceStation(15);
        String configuration = station.getStationConfig();
        System.out.println(configuration);


        /* Step 2:  Assign colonists to pods as follows:

            5 are in social pods
            8 are in kitchen pods
            1 is in a hygiene pod
            1 is in a sleeping pod.

          Check the status of all pods and report it.
        */
        int socialAmount = 5;
        int kitchenAmount = 8;
        int hygieneAmount = 1;
        int sleepingAmount = 1;

        ArrayList<Pod> arr = new ArrayList<Pod>();
        arr.addAll(station.getPods()); //Adding everything from pods to arr
        Iterator<Pod> it = arr.iterator();

        while (it.hasNext()) {
            Pod x = it.next();
            if (x.getType() == "Kitchen Pod") {
                x.setCurrentCapacity(kitchenAmount);
            } else if (x.getType() == "Sleeping Pod") {
                x.setCurrentCapacity(sleepingAmount);
            } else if (x.getType() == "Hygiene Pod") {
                x.setCurrentCapacity(hygieneAmount);
            } else if (x.getType() == "Social Pod") {
                x.setCurrentCapacity(socialAmount);
            }
        }

        String status = station.checkStatus();
        System.out.println(status);
    }
}

这是我的输出：

Pod type:Kitchen Pod    Current capacity:8  Max capacity:8
Pod type:Kitchen Pod    Current capacity:8  Max capacity:8
Pod type:Sleeping Pod   Current capacity:1  Max capacity:2
Pod type:Sleeping Pod   Current capacity:1  Max capacity:2
Pod type:Sleeping Pod   Current capacity:1  Max capacity:2
Pod type:Sleeping Pod   Current capacity:1  Max capacity:2
Pod type:Sleeping Pod   Current capacity:1  Max capacity:2
Pod type:Sleeping Pod   Current capacity:1  Max capacity:2
Pod type:Sleeping Pod   Current capacity:1  Max capacity:2
Pod type:Sleeping Pod   Current capacity:1  Max capacity:2
Pod type:Hygiene Pod    Current capacity:1  Max capacity:2
Pod type:Hygiene Pod    Current capacity:1  Max capacity:2
Pod type:Hygiene Pod    Current capacity:1  Max capacity:2
Pod type:Hygiene Pod    Current capacity:1  Max capacity:2
Pod type:Hygiene Pod    Current capacity:1  Max capacity:2
Pod type:Hygiene Pod    Current capacity:1  Max capacity:2
Pod type:Hygiene Pod    Current capacity:1  Max capacity:2
Pod type:Hygiene Pod    Current capacity:1  Max capacity:2
Pod type:Social Pod     Current capacity:5  Max capacity:10
Pod type:Social Pod     Current capacity:5  Max capacity:10

Answer 1

我认为这是因为你没有几种类型;你只有每种类型中的一种。您可能会为List中的每个元素分配相同的引用。当您更改该单个实例时，所有List元素都指向同一个元素，因此您似乎已经将它们全部搞砸了＃34;。

解决方案是为List中的每个元素创建一个新的Pod类型。这样你可以改变一个而不影响其他人。

这是一个展示我的意思的例子：

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

/**
 * Created by Michael
 * Creation date 3/9/2016.
 * @link https://stackoverflow.com/questions/35907239/how-can-i-manipulate-one-object-in-the-arraylist-without-messing-with-the-other/35907280#35907280
 */
public class Foo {
    private int value;

    public static void main(String [] args) {
        List<Foo> foos = new ArrayList<Foo>();
        foos.add(new Foo(1));
        foos.add(new Foo(2));

        System.out.println("before change: " + foos);
        foos.get(0).setValue(20);
        System.out.println("after  change: " + foos);
    }

    public Foo(int v) { this.setValue(v); }

    public void setValue(int v) { this.value = v; }

    public String toString() { return String.format("value: %d", this.value); }
}

如您所见，我在Foo中更改了List的一个实例;它对另一方的状态没有影响。

Answer 2

我认为您应该为每种类型添加标记以检查容量是否已设置。例如：

    boolean isKitchenPodSet = false, isSleepingPodSet = false,
    isHygienePodSet = false, isSocialPodSet = false;
    while (it.hasNext()) {
        Pod x = it.next();
        if (x.getType() == "Kitchen Pod" && !isKitchenPodSet ) {
            x.setCurrentCapacity(kitchenAmount);
            isKitchenPodSet = true;    
        } else if (x.getType() == "Sleeping Pod" && !isSleepingPodSet ) {
            x.setCurrentCapacity(sleepingAmount);
            isSleepingPodSet = true;
        } else if (x.getType() == "Hygiene Pod" && !isHygienePodSet ) {
            x.setCurrentCapacity(hygieneAmount);
            isHygienePodSet = true;
        } else if (x.getType() == "Social Pod" && !isSocialPodSet ) {
            x.setCurrentCapacity(socialAmount);
            isSocialPodSet  = true;
        }
    }

Answer 3

为什么不为每种Pod创建单独的ArrayList并在iterator上使用它而不是在那里设置容量？

List<Pod> kitchenPods = new ArrayList<Pod>();
// ... do the same for the remaining kinds of pod

while (it.hasNext()) {
        Pod x = it.next();
        if (x.getType() == "Kitchen Pod") {
            kitchenPods.add(x);
        } else if (x.getType() == "Sleeping Pod") {
            sleepingPods.add(x);
        } else if (x.getType() == "Hygiene Pod") {
            hygienePods.add(x);
        } else if (x.getType() == "Social Pod") {
           socialPods.add(x);
        }
    }

现在您已将它们分开，您可以加载相应的窗格。（为每个方法创建一个方法可能是个好主意）

    for(int i=0; i < kitchenPods.size(); i++){
         if (kitchenPods.get(i).getCapacity < kitchenPods.get(i).getMaxCapacity){
                 //  Load them up!
          }
    }

    // do the same for the rest of the Pods

当你把它们全部加载完毕后，你可以将它们全部添加到一个List中，以备你需要合并它们。

不确定这是否是您所需要的，但我希望这会有所帮助。

如何在不干扰其他对象的情况下操作arrayList中的一个对象？

3 个答案: