我已经实现了B-Tree，我已经给了toString在节点类中实现方法，但它在这一行children.forEach(c ->builder.append(c.toString(depth + 1)));中给出错误，我尝试了各种方法，但没有工作
这里是其他B-Tree文件和pdf，其中给出了toString方法和其他指令查看这些文件
toString代码
import java.util.Arrays;
import java.util.Comparator;
import java.util.LinkedList;
import java.util.List;
public class Node<E extends Comparable<E>> {
public int nodeLocation;
public int index;
private E[] keys = null;
int keysSize = 0;
public Node<E>[] children = null;
public Node<E>[] elements;
int childrenSize = 0;
private Comparator<Node<E>> comparator = new Comparator<Node<E>>() {
@Override
public int compare(Node<E> arg0, Node<E> arg1) {
return arg0.getKey(0).compareTo(arg1.getKey(0));
}
};
protected Node<E> parent = null;
Node(Node<E> parent, int maxKeySize, int maxChildrenSize) {
this.parent = parent;
this.keys = (E[]) new Comparable[maxKeySize + 1];
this.keysSize = 0;
this.children = new Node[maxChildrenSize + 1];
this.childrenSize = 0;
}
E getKey(int index) {
return keys[index];
}
int indexOf(E value) {
for (int i = 0; i < keysSize; i++) {
if (keys[i].equals(value))
return i;
}
return -1;
}
void addKey(E value) {
keys[keysSize++] = value;
Arrays.sort(keys, 0, keysSize);
}
E removeKey(E value) {
E removed = null;
boolean found = false;
if (keysSize == 0)
return null;
for (int i = 0; i < keysSize; i++) {
if (keys[i].equals(value)) {
found = true;
removed = keys[i];
} else if (found) {
// shift the rest of the keys down
keys[i - 1] = keys[i];
}
}
if (found) {
keysSize--;
keys[keysSize] = null;
}
return removed;
}
E removeKey(int index) {
if (index >= keysSize)
return null;
E value = keys[index];
for (int i = index + 1; i < keysSize; i++) {
// shift the rest of the keys down
keys[i - 1] = keys[i];
}
keysSize--;
keys[keysSize] = null;
return value;
}
int numberOfKeys() {
return keysSize;
}
Node<E> getChild(int index) {
if (index >= childrenSize)
return null;
return children[index];
}
int indexOf(Node<E> child) {
for (int i = 0; i < childrenSize; i++) {
if (children[i].equals(child))
return i;
}
return -1;
}
boolean addChild(Node<E> child) {
child.parent = this;
children[childrenSize++] = child;
Arrays.sort(children, 0, childrenSize, comparator);
return true;
}
boolean removeChild(Node<E> child) {
boolean found = false;
if (childrenSize == 0)
return found;
for (int i = 0; i < childrenSize; i++) {
if (children[i].equals(child)) {
found = true;
} else if (found) {
// shift the rest of the keys down
children[i - 1] = children[i];
}
}
if (found) {
childrenSize--;
children[childrenSize] = null;
}
return found;
}
Node<E> removeChild(int index) {
if (index >= childrenSize)
return null;
Node<E> value = children[index];
children[index] = null;
for (int i = index + 1; i < childrenSize; i++) {
// shift the rest of the keys down
children[i - 1] = children[i];
}
childrenSize--;
children[childrenSize] = null;
return value;
}
int numberOfChildren() {
return childrenSize;
}
/**
* {@inheritDoc}
*/
public String toStringg() {
return toString(0);
}
// // based on what toString() does, think about what ‘elements’ and ‘children’
// can be
private String toString(int depth) {
StringBuilder builder = new StringBuilder();
String blankPrefix = new String(new char[depth]).replace(" ", "t");
List<String> printedElements = new LinkedList<>();
for (Node<E> e : elements)
printedElements.add(e.toString());
String eString = String.join(" :: ", printedElements);
builder.append(blankPrefix).append(eString).append("n");
children.forEach(c -> builder.append(c.toString(depth + 1))); // this line is giving error
return builder.toString();
}
}
我已经给出了pdf文件，其中给出了指令和代码实现我曾试图改变孩子，但没有工作，我一定不会在给定的toString方法
做出改变Java中的数组不声明它们自己的行为(不要试图从JavaScript和TypeScript等语言中复制你的经验，其中数组有方法)。
因此，你不能在children数组上调用方法forEach()(这个方法可以通过Iterable接口的实现来访问，比如集合)。
您可以使用增强的for-loop:
for (Node<E> node : children) {
builder.append(node.toString(depth + 1));
}
或者，如果您将属性children声明为List，则可以与它一起使用forEach():
public List<Node<E>> children;
根据你的作业要求，这就是你应该做的。
这将需要更改所有使用children的方法，因为您不能像使用数组一样使用List进行拨号。也就是说，你需要使用List接口的行为。
children[i]会变成children.get(i)。children[i] = ...会变成children.set(i, ...)，或者children.add(...)。