java - 通用数组如何添加set方法？

Question

我想编写一个方法来帮助我在泛型类变量中存储一些内容。我有点不明白一个概念:(

我想编写一个方法来替换这个简单的解决方案:

a.myObject[0]=tracks;

当我将数组索引作为参数提供时，它将与其他元素一起使用

我想找出类似这个方法的东西(但作为一个设置值)。有人知道如何做吗？

E get(int i) {
    return (E) myObject[i];
}

我的源代码:

import java.util.Arrays;
import java.util.List;

public class GenericArray<E>{

private Object[] myObject;  

public GenericArray(int s) {
    myObject = new Object[s];
}

E get(int i) {
    return (E) myObject[i];
}


public static <Track> void main(String[] args) {

    GenericArray a = new GenericArray(100);

    List<String> tracks = Arrays.asList("One", "Two", "Three");

    PlayList play = new PlayList(tracks);

    a.myObject[0]=tracks;

    System.out.println(a.get(0));

}

}

Answer 1

无法创建通用数组，因此将其更改为集合。我对您的代码做了一些调整:

public class GenericArray<E extends Object> {

    private List<E> myObject;

    public GenericArray(int s) {
        //myObject = new E[s];//can not create a generic array
        myObject = new ArrayList<>(s);
    }

    public E get(int i) {
        return myObject.get(i);
    }

    public void set(int i, E object){
        myObject.set(i, object);
    }

    public static void main(String[] args) {

        GenericArray<Object> a = new GenericArray<>(100);

        List<String> tracks = Arrays.asList("One", "Two", "Three");

        PlayList play = new PlayList(tracks);

        a.set(0, tracks);

        System.out.println(a.get(0));

    }

}

嗯...我认为这是因为集合中从未添加任何内容。 (有能力但没有要素)。我查看了有关通用数组的评论，所以这是另一个示例，这个示例应该可以工作:

public class GenericArray<E extends Object> {
    private E[] myObject;

    public GenericArray(Class<E> c,int s) {
        //myObject = new E[s];//can not create a generic array
        @SuppressWarnings("unchecked")
        final E[] a = (E[]) Array.newInstance(c, s);
        myObject = a;
    }

    public E get(int i) {
        return myObject[i];
    }

    public void set(int i, E object){
        myObject[i] = object;
    }

    public static void main(String[] args) {

        GenericArray<Object> a = new GenericArray<>(Object.class,100);

        List<String> tracks = Arrays.asList("One", "Two", "Three");

        PlayList play = new PlayList(tracks);

        a.set(0, tracks);

        System.out.println(a.get(0));

    }

}