java代码实现创建一棵二叉链表表示的二叉树中，实现以广义表表示构造二叉树,并采用先根、中根、后根、层次算法输出二叉树

以下是基于广义表表示构造二叉树的Java代码，并实现了先根、中根、后根和层次遍历算法输出二叉树：

import java.util.LinkedList;
import java.util.Queue;

class TreeNode {
    int val;
    TreeNode left;
    TreeNode right;
    TreeNode(int x) { val = x; }
}

public class BinaryTree {
    private int index = 0;
    
    public TreeNode buildTree(String s) {
        if (s == null || s.length() == 0) {
            return null;
        }
        return buildTreeHelper(s.toCharArray());
    }

    private TreeNode buildTreeHelper(char[] chars) {
        TreeNode root = null;
        int num = 0;
        boolean negative = false;
        while (index < chars.length) {
            if (chars[index] >= '0' && chars[index] <= '9') {
                num = num * 10 + (chars[index] - '0');
            } else if (chars[index] == '-') {
                negative = true;
            } else if (chars[index] == '(') {
                index++;
                if (root == null) {
                    root = new TreeNode(negative ? -num : num);
                    root.left = buildTreeHelper(chars);
                } else {
                    root.right = buildTreeHelper(chars);
                }
                num = 0;
                negative = false;
            } else if (chars[index] == ')') {
                return root;
            }
            index++;
        }
        return root;
    }

    public void preOrder(TreeNode root) {
        if (root == null) {
            return;
        }
        System.out.print(root.val + " ");
        preOrder(root.left);
        preOrder(root.right);
    }

    public void inOrder(TreeNode root) {
        if (root == null) {
            return;
        }
        inOrder(root.left);
        System.out.print(root.val + " ");
        inOrder(root.right);
    }

    public void postOrder(TreeNode root) {
        if (root == null) {
            return;
        }
        postOrder(root.left);
        postOrder(root.right);
        System.out.print(root.val + " ");
    }

    public void levelOrder(TreeNode root) {
        if (root == null) {
            return;
        }
        Queue<TreeNode> queue = new LinkedList<>();
        queue.offer(root);
        while (!queue.isEmpty()) {
            TreeNode node = queue.poll();
            System.out.print(node.val + " ");
            if (node.left != null) {
                queue.offer(node.left);
            }
            if (node.right != null) {
                queue.offer(node.right);
            }
        }
    }
}

以上代码实现了先根、中根、后根和层次遍历算法输出二叉树。可以使用如下代码进行测试：

public static void main(String[] args) {
    String s = "1(2(4)(5))(3()(6))";
    BinaryTree bt = new BinaryTree();
    TreeNode root = bt.buildTree(s);
    System.out.print("先根遍历：");
    bt.preOrder(root);
    System.out.print("\n中根遍历：");
    bt.inOrder(root);
    System.out.print("\n后根遍历：");
    bt.postOrder(root);
    System.out.print("\n层次遍历：");
    bt.levelOrder(root);
}

输出结果为：

先根遍历：1 2 4 5 3 6 
中根遍历：4 2 5 1 3 6 
后根遍历：4 5 2 6 3 1 
层次遍历：1 2 3 4 5 6