java 泛型数组和 Classcastexception

Question

我声明了 BinaryTree 如下：

public class BinaryTree<T extends Comparable<T>> {}

但是当我打电话给

Character[] actual = binaryTreeChar.preOrderTraversal(root, Character[].class);

它正在抛出如下异常。

java.lang.ClassCastException: [[Ljava.lang.Character; cannot be cast to [Ljava.lang.Comparable;

有没有更好的方法来处理这些情况？

public T[] preOrderTraversal(BinaryNode<T> root, Class<T[]> clazz) {
        if (root == null)
            return null;
        T[] array = (T[]) Array.newInstance(clazz, count);
        Stack<BinaryNode<T>> stack = new Stack<>();
        stack.push(root);
        int i = 0;
        while (!stack.empty()) {
            BinaryNode<T> next = stack.pop();
            array[i++] = next.data;
            if (next.right != null)
                stack.push(next.right);
            if (next.left != null)
                stack.push(next.left);
        }
        return array;
    }


}

Answer 1

应该是：

public T[] preOrderTraversal(BinaryNode<T> root, Class<T> clazz)

并且：

Character[] actual = binaryTreeChar.preOrderTraversal(root, Character.class);

就像现在一样，您正在创建 Character[][] 的实例（即二维数组）。

传给Array.newInstance的Class是数组的组件类型，不是数组类型

Object java.lang.reflect.Array.newInstance(Class componentType, int length) throws NegativeArraySizeException

Creates a new array with the specified component type and length...

Parameters:

componentType the Class object representing the component type of the new array
length the length of the new array

java 泛型数组和 Classcastexception

java generic array and Classcast exception

java

arrays

generics

classcastexception