Java 面向对象编程多个 class 实例

Question

自从我自学了编程，我想我应该开始创建适当的 classes 和变量，但我似乎不太明白。

我读到首先我需要一个 interface，所以我把我的看起来像这样：

public interface PitchInterface {
    void setOccuranceTime(float occuranceTime);
    float getOccuranceTime();
    void setPitch(float pitch);
    float getPitch();
}

其次，我制作了一个 class 实现了 interface:

public class Pitch implements PitchInterface{

    float occuranceTime;
    float pitch;

    @Override
    public void setOccuranceTime(float occuranceTime) {
        this.occuranceTime = occuranceTime;
    }

    @Override
    public float getOccuranceTime() {
        return occuranceTime;
    }

    @Override
    public void setPitch(float pitch) {
        this.pitch = pitch;
    }

    @Override
    public float getPitch() {
        return pitch;
    }
}

现在我需要给 Pitch 赋值，这就是我现在卡住的地方：

public class Foo {

    Pitch pitch = new Pitch();
    String[] pitches;
    List<Pitch> listOfPitches = new ArrayList<Pitch>();
    List<String> wordsList = new ArrayList<String>();

public List<Pitch> getListOfPitches(){
    getPitches();
    for (String pitchString: pitches) {
        makeListOfPitches(pitch, pitchString);
    }
    return listOfPitches;
}

public void makeListOfPitches(Pitch pitch, String pitchString){
    pitch.setPitch(getPitchesInfo(pitchString, 0));
    pitch.setOccuranceTime(getPitchesInfo(pitchString, 1));
    listOfPitches.add(pitch);
}

    public List<String> getWordsList(){
        //To-do make words out of Pitches and add them to list
        return wordsList;
    }



    public String[] getPitches() {
        pitches = pitchesRaw.split("\r?\n");
        return pitches;
    }

    private float getPitchesInfo(String pitch, int position){
        String[] frequencyAndTime = pitch.split("\:");
        if(position == 0){
            return Float.parseFloat(frequencyAndTime[0].replace(',', '.'));
        }
        if(position == 1){
            return Float.parseFloat(frequencyAndTime[1].replace(',', '.'));
        }
        else return 0;
    }

    String pitchesRaw = "0,14:23281,61\n" +
            "0,23:53,65\n" +
            "0,37:72,53\n" +
            "0,56:86,09\n" +
            "0,60:88,58\n" +
            "0,65:87,45\n" +
            "0,70:87,11\n" +
            "0,74:89,56\n" +
            "0,79:96,22\n" +
            "0,84:23288,24\n" +
            "0,88:103,92\n" +
            "0,93:107,46\n" +
            "0,98:108,02\n" +
            "1,02:107,51\n" +
            "1,07:104,92\n" +
            "1,11:105,94\n" +
            "1,16:106,40\n";
    }

最后从 Main 初始化它 class:

public static void main(String[] args) {
    Foo listOfWordsAndPithes = new Foo();
    List<Pitch> list = listOfWordsAndPithes.getListOfPitches();
    for (Pitch pitch: list) {
        System.out.println(pitch.getPitch());
    }
}

首先，如果我在循环中打印出所有 pitches，如上所示，我将得到如下所示的值作为输出。但我想要的是每个音高都具有从 pitchesRaw
获得的不同值
106.4 106.4 106.4 106.4 106.4 106.4 106.4 106.4 106.4 106.4 106.4 106.4 106.4 106.4 106.4 106.4 106.4
其次，如果我需要通过将多个 Pitches 添加到一个列表中来制作 words list 音高（例如将 6 个不同的音高添加到 1 个列表中）然后添加那些 Pitches 进入另一个列表，这将是新列表的第一个元素。那么我是否需要创建另一个名为 Word 的 class 并在那里定义什么词以及如何 set/get 它？
第三我看评论说这里不需要使用Interface。我什么时候知道可以使用接口，什么时候不能？

Answer 1

回答你问题的最后一部分，在这里使用接口没有好坏之分，你实际上是在为你的getters和setters创建一个接口，是否有必要取决于你想如何使用接口。看起来你的情况没有必要。看看Java Interface Usage Guidelines -- Are getters and setters in an interface bad?

关于你的第二个问题，你可能也不需要单独的 class 来实例化音高列表，word 是否真的有意义并且会在其他地方实例化为对象？如果您只想要一个列表，只需按照上面 List<Pitch> word = new ArrayList<Pitch>(); 所做的操作，然后将球场添加到列表中即可。

Java 面向对象编程多个 class 实例

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object-oriented-analysis