创建使用Class对象通用的二维数组 [英] Creating generic two-dimensional array using Class object

问题描述

我有泛型类＆LT; T＆gt;在构造函数中提供对象。我想创建二维数组 T [] [] 在此构造，这是可能的但？

I have generic type with Class<T> object provided in constructor. I want to create two-dimensional array T[][] in this constructor, is this however possible?

推荐答案

同的Java如何：通用阵列创建而是扩大到2D：

import java.lang.reflect.Array;

public class Example <T> {

    private final Class<? extends T> cls;

    public Example (Class<? extends T> cls) {
        this.cls = cls;
    }

    public void arrayExample () {
        // a [10][20] array
        @SuppressWarnings("unchecked")
        T[][] array = (T[][])Array.newInstance(cls, 10, 20);
        System.out.println(array.length + " " + array[0].length + " " + array.getClass());
    }

    public static final void main (String[] args) {
        new Example<Integer>(Integer.class).arrayExample();
    }

}

请注意阅读上述申诉委员会的评论之后：要扩展到多个维度，只要添加的维和[]参数的newInstance（）（CLS是A类，D1至D5是整数）：

Note after reading JAB's comment above: To extend to more dimensions, just add []'s and dimension parameters to newInstance() (cls is a Class, d1 through d5 are integers):

T[] array = (T[])Array.newInstance(cls, d1);
T[][] array = (T[][])Array.newInstance(cls, d1, d2);
T[][][] array = (T[][][])Array.newInstance(cls, d1, d2, d3);
T[][][][] array = (T[][][][])Array.newInstance(cls, d1, d2, d3, d4);
T[][][][][] array = (T[][][][][])Array.newInstance(cls, d1, d2, d3, d4, d5);

请参阅<$c$c>Array.newInstance()了解详情。

See Array.newInstance() for details.

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