Question

我正在努力重建游戏＆＃34; The Oregon Trail＆＃34;并创建了一个对象数组，但无法弄清楚如何在超类中使用这些方法。我有一个超类Location和子类City Fort River和Landmark。这是我实例化数组的代码：

    City     independence      = new City("Independence", 102);
    River    kansas            = new River("Kansas", 82);
    River    bigBlue           = new River("Big Blue River", 118);
    Fort     kearney           = new Fort("Fort Kearney", 86);
    Landmark chimneyRock       = new Landmark("Chimney Rock", 86);
    Fort     laramie           = new Fort("Fort Laramie", 190);
    Landmark independenceRock  = new Landmark("Independence Rock", 102);
    Landmark southPass         = new Landmark("South Pass", 57, 125);
    River    green             = new River("Green River", 143);
    Fort     bridger           = new Fort("Fort Bridger", 162);
    Landmark sodaSprings       = new Landmark("Soda Springs", 57);
    Fort     hall              = new Fort("Fort Hall", 182);
    River    snake             = new River("Snake River", 113);
    Fort     boise             = new Fort("Fort Boise", 160);
    Landmark blueMountains     = new Landmark("Blue Mountains", 55, 125);
    Fort     wallaWalla        = new Fort("Fort Walla Walla", 120);
    Landmark dalles            = new Landmark("The Dalles", 100);

    kansas.setWidth(620);
    kansas.setDepth(4);
    bigBlue.setWidth(300);
    bigBlue.setDepth(6);
    green.setWidth(400);
    green.setDepth(20);
    snake.setWidth(1000);
    snake.setDepth(7);

    Object[] locations = new Object[] {
        independence,
        kansas,
        bigBlue,
        kearney,
        chimneyRock,
        laramie,
        independenceRock,
        southPass,
        green,
        bridger,
        sodaSprings,
        hall,
        snake,
        boise,
        blueMountains,
        wallaWalla,
        dalles
    };

类实例化的参数是（字符串名称，到下一个地标的int距离）或（字符串名称，到选项A的int距离，到选项B的距离），因为道路中有叉子。这应该与我的问题无关。

Answer 1

您想拨打什么方法？

通常，如果您要将一堆对象放在同一个数组或同一个集合中，那是因为您计划在所有上执行一个或多个常用方法（或者，可在任何上执行。）

在这种情况下，你通常会要声明一个interface来捕捉对象都有的共同点。

在您的示例中，您有Landmark，Fort和River个对象。他们有什么共同点？嗯，首先，他们都有名字。所以你可能有

interface Location {
    String getName();
    ...other methods that apply to all different kinds of location...
}

然后你可能有

class Landmark implements Location {
    String getName() { return ...; }
    ...other methods that apply to all different kinds of location...
    ...other methods that only apply to Landmarks...
}

class Fort implements Location {
    String getName() { return ...; }
    ...other methods that apply to all different kinds of location...
    ...other methods that only apply to Forts...
}

etc.

然后，如果你声明你的数组......

Location locations[] = new Location[] { independence, kansas, bigBlue, ...};

编译器允许您将任何Location方法应用于数组成员。

for (int i=0 ; i<locations.length ; i++) {
    System.out.println(locations[i].getName());
}

如何访问我放入数组的对象中的方法？

1 个答案: