将条件移动到 Class 时出错

Question

我正在开发涉及实施一些重构技术的硬件，但我运行遇到了一个我似乎无法发现的错误。我有以下方法，该方法最初位于 Fish class 中，我移入了名为 Strategy

的 class

public class Strategy
{
    public void move (Fish fish, Pond pond)
    {
        if (fish.getHunger() < 0.2)
        {
            if (fish.getSize() < 7.0)
            {
                double[] location = pond.findNearestPlant(fish.getX(), fish.getY());
                fish.swimTowards(location[0], location[1]);
            }
            else
            {
                double[] location = pond.findNearestSmallFish(fish.getX(), fish.getY());
                fish.swimTowards(location[0], location[1]);
            }
        }
        else
        {
            // There are more conditionals in this block.  I haven't done anything with them yet so I didn't put them in.
        }
    }
}

我正在尝试将 if 块中的条件转换为 2 个单独的 classes，它们也位于我的 Strategy.java 文件中。

class SmallFish extends Strategy
{
    public void move (Fish fish, Pond pond)
    {
        double[] location = pond.findNearestPlant(fish.getX(), fish.getY());
        fish.swimTowards(location[0], location[1]);
    }
}

class BigFish extends Strategy
{
    public void move (Fish fish, Pond pond)
    {
        double[] location = pond.findNearestSmallFish(fish.getX(), fish.getY());
        fish.swimTowards(location[0], location[1]);
    }
}

回到 Fish class 我添加了几行代码来确定调用哪个 class：

import java.lang.Math;
import java.util.Random;

public class Fish
{
    private static Random random = new Random();
    private static int numberOfFish = 0;

    private double hunger;
    private double size;
    private double x;
    private double y;
    private int id;

    // I added this line
    private Strategy strategy;

    private FishReport myFishReport = null;

    public Fish(double x, double y, FishReport report)
    {
        hunger = 0.9;
        size = 1.0;

        // Put it in the pond
        this.x = x;
        this.y = y;

        id = numberOfFish;
        numberOfFish++;

        // I added this code
        if (hunger < 0.2 && size < 7.0)
            this.strategy = new SmallFish();
        else if (hunger < 0.2 && size >= 7.0)
            this.strategy = new BigFish();
        else
            this.strategy = new Strategy();

        myFishReport = report;
        if(myFishReport != null)
        {
            myFishReport.updateHunger(hunger);
            myFishReport.updateSize(size);
            myFishReport.updateLocation(x, y);
        }
    }

    public void age(double timePassed)
    {
        double deltaSize = size * (1 + hunger * Math.exp(-size * timePassed));
        size = size + deltaSize;

        hunger = hunger * Math.exp(-deltaSize/size);

        myFishReport.updateHunger(hunger);
        myFishReport.updateSize(size);   
    }

    public void move(Pond pond)
    {
        strategy.move(this, pond);
    }

    // More methods below that I did not touch.  Left out to keep code as short as possible.
}

我的测试套件在添加 SmallFish class 后仍然通过，但在添加 BigFish class:

后我失败了

JUnit Test Results:
testMoveStarving(FishTests): Starving fish should move expected:<10.2981> but was:<10.3965129880783>
Total number of tests: 8
Total number of failures: 1

这是失败的测试：

public void testMoveStarving()
{
    // Create a new fish and report
    FishReport report = new FishReport();
    Fish fish = new Fish(10, 20, report);

    // Make a pond
    Pond pond = new Pond();

    // Grow the fish until starving
    fish.age(20);
    fish.age(20);
    fish.age(20);
    fish.age(20);

    // Move the fish, and check the new location
    fish.move(pond);

    // Check the new location
    assertEquals("Starving fish should move", 10.2981, report.getLocation()[0], 0.001);
    assertEquals("Starving fish should move", 20.5963, report.getLocation()[1], 0.001);
}

我唯一能想到的是我在 Fish 构造函数中对 BigFish class 的条件不准确。我已经盯着这个看一个多小时了，所以我想我只需要另一双眼睛来指出我哪里出错了。如果有比 Fish 构造函数中的条件更极端的东西，请尝试给出提示而不是答案。就像我说的，这是硬件作业的一部分。

先谢谢你

编辑 1 - 我忘记在 Fish class 中添加更改后的 move() 方法。现在已经修复了。

编辑 2 - 失败的测试已发布。测试调用 Fish class 中的 age() 方法，所以我也添加了它。

Answer 1

不知道你的代码的其余部分是什么样子，但如果鱼的 size 或 hunger 在构造后发生变化，你将不再使用正确的策略。（就目前而言，您所有的鱼都将使用 Strategy 策略，而不是 BigFish 和 SmallFish。）

将策略选择保留在 move 方法中而不是构造函数中可能更有意义。

将条件移动到 Class 时出错

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