Question

我想为BinaryTree写一个自定义的迭代器。此迭代器应返回accuracies = [] losses = [] for i in range(0, len_X // batch_size + 1: X_batch, Y_batch = next_batch( total=len_X, images=X, labels=Y, batch_size=batch_size, index=i ) los, acc= sess.run([loss, accuracy]) accuracies.append(acc) losses.append(loss) test_acc = np.mean(accuracies) test_loss = np.mean(losses)个对象。在递归调用fillList的行中，文件Node<?>中出现编译错误：InorderIterator

错误是：fillList(currentNode.getLeft());

有人可以向我解释为什么我的方法无效吗？或如何解决

Error:(14, 37) java: incompatible types: rclib.Node cannot be converted to T

Node.java

package rclib; public class Node<T extends Comparable<T>> { T key; Node<T> left; Node<T> right; public Node(T key, Node left, Node right) { this.key = key; this.left = left; this.right = right; } public Node(T key) { this(key, null, null); } public Node<T> getLeft() { return left; } public Node<T> getRight() { return right; } public T getKey() { return key; } }

InorderIterator.java

package rclib; import java.util.*; public class InorderIterator<T extends Node<?>> implements Iterator<T> { LinkedList<T> list; public InorderIterator(T root) { list = new LinkedList<T>(); fillList(root); } public void fillList(T currentNode) { if (currentNode == null) return; fillList(currentNode.getLeft()); list.add(currentNode); fillList(currentNode.getRight()); } @Override public boolean hasNext() { return !list.isEmpty(); } @Override public T next() { return list.removeFirst(); } }

AVLTree.java

Answer 1

您也许应该做类似的事情：

package rclib;
import java.util.*;

public class InorderIterator<T extends Comparable<T>> implements Iterator<Node<T>> {
    LinkedList<Node<T>> list;

    public InorderIterator(Node<T> root) {
        list = new LinkedList<Node<T>>();
        fillList(root);
    }

    public void fillList(Node<T> currentNode) {
        if (currentNode == null) return;
        fillList(currentNode.getLeft());
        list.add(currentNode);
        fillList(currentNode.getRight());
    }

    @Override
    public boolean hasNext() {
        return !list.isEmpty();
    }

    @Override
    public Node<T> next() {
        return list.removeFirst();
    }
}

Answer 2

您必须明确指定您使用Node而不是? extends Node，这可能最终不符合正确的用法。

public static class InorderIterator<T extends Comparable<T>> implements Iterator<Node<T>> {
    LinkedList<Node<T>> list;

    public InorderIterator(Node<T> root) {
        list = new LinkedList<>();
        fillList(root);
    }

    public void fillList(Node<T> currentNode) {
        if (currentNode == null) return;
        fillList(currentNode.getLeft());
        list.add(currentNode);
        fillList(currentNode.getRight());
    }

    @Override
    public boolean hasNext() {
        return !list.isEmpty();
    }

    @Override
    public Node<T> next() {
        return list.removeFirst();
    }
}

用Java为二叉树编写通用迭代器

2 个答案: