多维长度数组反射java

How do I find the length of a multi-dimensional array with reflection on java?

如何在java上找到带有反射的多维数组的长度？

5 个解决方案

#1

Java arrays have lengths per instance, not all arrays in the same dimension have to have equals lengths. That said, you can get the lengths of instances in the.

Java数组在每个实例中都有长度，并非同一维度中的所有数组都必须具有等长。也就是说，你可以获得实例的长度。

Dimensions can be counted by the number of '[' in their name, this is quicker than descending the type hierarchy. The following code:

维度可以通过名称中的“[”数来计算，这比降序类型层次更快。以下代码：

        int[][][] ary = {{{0},{1}}};

        Class cls = ary.getClass();

        boolean isAry = cls.isArray();
        String clsName = cls.getName();

        System.out.println("is array=" + isAry);
        System.out.println("name=" + clsName);

        int nrDims = 1 + clsName.lastIndexOf('[');

        System.out.println("nrDims=" + nrDims);

        Object orly = ary;

        for (int n = 0; n < nrDims; n++) {

            int len = Array.getLength(orly);

            System.out.println("dim[" + n + "]=" + len);

            if (0 < len) {
                orly = Array.get(orly, 0);
            }
        }

gives the following output:

给出以下输出：

is array=true
name=[[[I
nrDims=3
dim[0]=1
dim[1]=2
dim[2]=1

#2

There is no such thing as "length" for multi-dimensional array; it may not be rectangular. I'm guessing you're talking about the number of dimensions. You need to descend into it iteratively and count.

多维数组没有“长度”这样的东西;它可能不是矩形的。我猜你在谈论尺寸的数量。你需要迭代地进入它并计数。

public int getDimensionCount(Object array) {
  int count = 0;
  Class arrayClass = array.getClass();
  while ( arrayClass.isArray() ) {
    count++;
    arrayClass = arrayClass.getComponentType();
  }
  return count;
}

#3

Class clazz = Class.forName("ReflectionTest");    
Method m = clazz.getDeclaredMethod("getArray");
Object o1 = m.invoke(o, arg);
int array[][] = (int[][])o1;
System.out.println("Array length: " + array.length);
System.out.println("Array length: " + array[0].length);

#4

Use java.lang.reflect.Array.getLength(obj).

使用java.lang.reflect.Array.getLength（obj）。

#5

If you like me were trying to get the number of dimensions and the size of them then:

如果你喜欢我试图获得尺寸和尺寸，那么：

private static int[] getDimentionsOf(final Object expectedArray) {
    if (!expectedArray.getClass().isArray()) {
        return new int[0];
    }
    final int dimensionSize = Array.getLength(expectedArray);
    final int[] innerDimensions =
                    (expectedArray.getClass().getComponentType().isArray())
                                    ? getDimentionsOf(Array.get(expectedArray, 0))
                                    : new int[0];
    final int lenghtPlusOne = innerDimensions.length + 1;
    final int[] newDimensions = new int[lenghtPlusOne];
    System.arraycopy(innerDimensions, 0, newDimensions, 1, innerDimensions.length);
    newDimensions[0] = dimensionSize;
    return newDimensions;
}

#1