Java:将字符串转换为树

class TreeNode {
    String value;
    TreeNode left;
    TreeNode right;
    
    public TreeNode(String value) {
        this.value = value;
        this.left = null;
        this.right = null;
    }
}

public TreeNode buildTree(String str) {
    if (str == null || str.length() == 0) {
        return null;
    }
    
    // 找到根节点的值
    int index = str.indexOf(":");
    String rootValue = str.substring(0, index);
    
    // 构建根节点
    TreeNode root = new TreeNode(rootValue);
    
    // 递归构建左子树和右子树
    String[] children = str.substring(index + 1).split(",");
    if (children.length > 0 && !children[0].equals("")) {
        root.left = buildTree(children[0]);
    }
    if (children.length > 1 && !children[1].equals("")) {
        root.right = buildTree(children[1]);
    }
    
    return root;
}

public static void main(String[] args) {
    String str = "A:B,C";
    TreeNode root = buildTree(str);
    
    // 输出树的结构
    printTree(root);
}

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