二叉树的具体特性和细节知识点，自行百度，直接上代码。

节点：节点内容、左子孩子、右子孩子、父亲

class Node {

    private int data;

    private Node leftChild;

    private Node rightChild;

    private Node parent;

    public Node getParent() {

        return parent;

    }

    public void setParent(Node parent) {

        this.parent = parent;

    }

    public Node(int data, Node leftChild, Node rightChild, Node parent) {

        this.data = data;

        this.leftChild = leftChild;

        this.rightChild = rightChild;

        this.parent = parent;

    }

    public int getData() {

        return data;

    }

    public void setData(int data) {

        this.data = data;

    }

    public Node getLeftChild() {

        return leftChild;

    }

    public void setLeftChild(Node leftChild) {

        this.leftChild = leftChild;

    }

    public Node getRightChild() {

        return rightChild;

    }

    public void setRightChild(Node rightChild) {

        this.rightChild = rightChild;

    }

}

二叉树构造和操作：

public class BinaryTree {

    private Node root;//根节点

    //插入节点

    public void insertNode(Node root, Node node) {

        Node current = root;

        while (true) {

            if (node.getData() < current.getData()) {

                if (current.getLeftChild() == null) {

                    node.setParent(current);

                    current.setLeftChild(node);

                    break;

                } else {

                    current = current.getLeftChild();

                }

            } else {

                if (current.getRightChild() == null) {

                    node.setParent(current);

                    current.setRightChild(node);

                    break;

                } else {

                    current = current.getRightChild();

                }

            }

        }

    }

    //删除节点

    public void deleteNode(Node node) {

        if (node.equals(root)) {

            root = null;

        } else if (node.getParent() != null) {

            if (node == node.getParent().getLeftChild()) {

                node.getParent().setLeftChild(null);

            } else {

                node.getParent().setRightChild(null);

            }

        }

    }

    //获取某节点的高度

    public int geHeight(Node node) {

        if (node == null) {

            return 0;

        } else {

            int leftHeight = geHeight(node.getLeftChild());

            int rightHeight = geHeight(node.getRightChild());

            int max = Math.max(leftHeight, rightHeight);

            return max + 1;

        }

    }

    //获取某节点的子节点个数

    public int getChildNodes(Node node) {

        if (node == null) {

            return 0;

        } else {

            int leftNodes = getChildNodes(node.getLeftChild());

            int rightNodes = getChildNodes(node.getRightChild());

            return leftNodes + rightNodes + 1;

        }

    }

    //先序遍历树

    public void PreOrder(Node root) {

        if (root == null)

            return;

        System.out.print(root.getData() + " ");

        PreOrder(root.getLeftChild());

        PreOrder(root.getRightChild());

    }

    //中序

    public void MidOrder(Node root) {

        if (root == null) return;

        MidOrder(root.getLeftChild());

        System.out.print(root.getData() + " ");

        MidOrder(root.getRightChild());

    }

    //后序

    public void LastOrder(Node root) {

        if (root == null) return;

        LastOrder(root.getLeftChild());

        LastOrder(root.getRightChild());

        System.out.print(root.getData() + " ");

    }

    public BinaryTree() {

    }

    public BinaryTree(Node root) {

        this.root = root;

    }

    public Node getRoot() {

        return root;

    }

    public void setRoot(Node root) {

        this.root = root;

    }

}

测试：

public class Main {

    public static void main(String[] args) {

        BinaryTree bt = new BinaryTree(new Node(1, null, null, null));

        int a[] = {5, 3, 2, 7, 4, 9, 8};

        for (int i = 0; i < 7; i++) {

            bt.insertNode(bt.getRoot(), new Node(a[i], null, null, null));

        }

//        System.out.println(bt.geHeight(root));//高度

//        bt.PreOrder(root);

//        System.out.println();

//        bt.MidOrder(root);

//        System.out.println();

//        bt.LastOrder(root);

//        System.out.println();

//        bt.deleteNode(bt.getRoot());

//        bt.PreOrder(bt.getRoot());

 //       System.out.println(bt.getChildNodes(bt.getRoot()));//子节点数

    }

}