我有一个二叉树程序，它在父项的左边排序较小/相等的数字，在父项的右边排序较大的数字，我想打印出它的图表，但我不是知道如何打印它以便格式化。此外，print方法应该是TreeDriver类的一部分，还是TreeNode类的一部分，以递归方式访问每个节点。
以下是课程：
TreeDriver：
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
/**
* This class serves as the driver for a generic TreeNode, giving it the type of Integer.
*/
public class TreeDriver
{
//region Instance Variables
TreeNode<Integer> root;
//endregion
//region Constructors
public TreeDriver() throws FileNotFoundException
{
fill();
System.out.println("Count: " + root.getCount());
}
//endregion
//region Public Methods
public void fill() throws FileNotFoundException
{
Scanner reader = new Scanner(new File("TreeValueSource"));
String temp;
Integer entry;
makeRoot();
while (reader.hasNext())
{
temp = reader.nextLine();
if (temp.contains("//"))
{
if (reader.hasNext())
temp = reader.nextLine();
else break;
}
else if (checkInt(temp))
{
entry = new Integer(temp);
root.add(entry);
}
else System.out.println("ERROR IN FILL");
}
}
private void makeRoot()
{
Scanner scan = new Scanner(System.in);
System.out.println("Enter a root value(default 50): ");
String input = scan.next();
if (checkInt(input))
root = new TreeNode<>(new Integer(input));
else
root = new TreeNode<>(50);
}
public void printCount()
{
System.out.println(root.getCount());
}
//endregion
//region Private Methods
private boolean checkInt(String candidate)
{
boolean parsable = true;
try
{
Integer.parseInt(candidate);
} catch (NumberFormatException e)
{
parsable = false;
}
return parsable;
}
//endregion
}
树节点：
public class TreeNode<T extends Comparable<T>>
{
//region Instance Variables
//Links
private TreeNode<T> leftChild; //Left Link
private TreeNode<T> rightChild; //Right Link
//Properties
private T data; //Info Stored by the TreeNode
private int childCount; //Number of Children
private int depth; //Level of the Node in the Tree
//endregion
//region Constructors
public TreeNode(T data, int parentDepth)
{
leftChild = null;
rightChild = null;
childCount = 0;
depth = parentDepth + 1;
this.data = data;
}
public TreeNode(T data)
{
leftChild = null;
rightChild = null;
childCount = 0;
depth = 0;
this.data = data;
System.out.println("A Root was Created");
}
//endregion
//region Public Methods
/**
* ADD
* Adds a new TreeNode to the tree. Left if equal or smaller, Right if larger
*
* @param data The data held by the TreeNode
* @see TreeNode
*/
public void add(T data)
{
if (this.data.compareTo(data) <= 0)
{
addLeft(data);
} else if (this.data.compareTo(data) > 0)
{
addRight(data);
} else
{
System.out.println("ERROR IN TREENODE.ADD");
}
}
public int getCount()
{
return count();
}
/**
* IS LEAF
* Determines if the current node has no children
*
* @return True if no children, False otherwise
*/
public boolean isLeaf()
{
return childCount == 0;
}
//endregion
//region Private Methods
//Adds the data to the left of this.TreeNode
private void addLeft(T data)
{
if (null == leftChild)
{
leftChild = new TreeNode(data, depth);
childCount += 1;
} else
leftChild.add(data);
}
//Adds the data to the right of this.TreeNode
private void addRight(T data)
{
if (null == rightChild)
{
rightChild = new TreeNode(data, depth);
childCount += 1;
} else
rightChild.add(data);
}
/**
* COUNT
* Recursively counts the number of TreeNodes
*
* @return the number of TreeNodes, 0 if an error
*/
private int count()
{
if (isLeaf())
{
return 1;
} else if (childCount == 2)
{
return 1 + leftChild.count() + rightChild.count();
} else if (null == leftChild)
{
return 1 + rightChild.count();
} else if (null == rightChild)
{
return 1 + leftChild.count();
} else
{
System.out.println("ERROR IN COUNT AT DEPTH " + depth);
return 0;
}
}
//endregion
}
答案 0 :(得分：2)
您可以将此答案用作模型
[How to print binary tree diagram?
修改BtreePrinter类。不，你不应该把print方法放在TreeDriver类中。
class Node<T extends Comparable<?>> {
Node<T> left, right;
T data;
public Node(T data) {
this.data = data;
}
}
class BTreePrinter {
public static <T extends Comparable<?>> void printNode(Node<T> root) {
int maxLevel = BTreePrinter.maxLevel(root);
printNodeInternal(Collections.singletonList(root), 1, maxLevel);
}
private static <T extends Comparable<?>> void printNodeInternal(List<Node<T>> nodes, int level, int maxLevel) {
if (nodes.isEmpty() || BTreePrinter.isAllElementsNull(nodes))
return;
int floor = maxLevel - level;
int endgeLines = (int) Math.pow(2, (Math.max(floor - 1, 0)));
int firstSpaces = (int) Math.pow(2, (floor)) - 1;
int betweenSpaces = (int) Math.pow(2, (floor + 1)) - 1;
BTreePrinter.printWhitespaces(firstSpaces);
List<Node<T>> newNodes = new ArrayList<Node<T>>();
for (Node<T> node : nodes) {
if (node != null) {
System.out.print(node.data);
newNodes.add(node.left);
newNodes.add(node.right);
} else {
newNodes.add(null);
newNodes.add(null);
System.out.print(" ");
}
BTreePrinter.printWhitespaces(betweenSpaces);
}
System.out.println("");
for (int i = 1; i <= endgeLines; i++) {
for (int j = 0; j < nodes.size(); j++) {
BTreePrinter.printWhitespaces(firstSpaces - i);
if (nodes.get(j) == null) {
BTreePrinter.printWhitespaces(endgeLines + endgeLines + i + 1);
continue;
}
if (nodes.get(j).left != null)
System.out.print("/");
else
BTreePrinter.printWhitespaces(1);
BTreePrinter.printWhitespaces(i + i - 1);
if (nodes.get(j).right != null)
System.out.print("\\");
else
BTreePrinter.printWhitespaces(1);
BTreePrinter.printWhitespaces(endgeLines + endgeLines - i);
}
System.out.println("");
}
printNodeInternal(newNodes, level + 1, maxLevel);
}
private static void printWhitespaces(int count) {
for (int i = 0; i < count; i++)
System.out.print(" ");
}
private static <T extends Comparable<?>> int maxLevel(Node<T> node) {
if (node == null)
return 0;
return Math.max(BTreePrinter.maxLevel(node.left), BTreePrinter.maxLevel(node.right)) + 1;
}
private static <T> boolean isAllElementsNull(List<T> list) {
for (Object object : list) {
if (object != null)
return false;
}
return true;
}
}