Java将List年级班级课程转为树形结构

您可以使用递归算法将List年级、班级和课程数据转换为树形结构。以下是一个示例代码：

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

class TreeNode {
    private String name;
    private List<TreeNode> children;

    public TreeNode(String name) {
        this.name = name;
        this.children = new ArrayList<>();
    }

    public String getName() {
        return name;
    }

    public List<TreeNode> getChildren() {
        return children;
    }

    public void addChild(TreeNode child) {
        children.add(child);
    }
}

public class Main {
    public static void main(String[] args) {
        // 生成样例数据
        Map<String, List<String>> gradeData = new HashMap<>();
        gradeData.put("Grade 1", List.of("Class A", "Class B"));
        gradeData.put("Grade 2", List.of("Class C", "Class D"));
        gradeData.put("Grade 3", List.of("Class E"));

        Map<String, List<String>> classData = new HashMap<>();
        classData.put("Class A", List.of("Math", "Science"));
        classData.put("Class B", List.of("English"));
        classData.put("Class C", List.of("History", "Geography"));
        classData.put("Class D", List.of("Physics", "Chemistry"));
        classData.put("Class E", List.of("Art"));

        // 转换为树形结构
        TreeNode root = new TreeNode("School");
        for (String grade : gradeData.keySet()) {
            TreeNode gradeNode = new TreeNode(grade);
            root.addChild(gradeNode);
            List<String> classes = gradeData.get(grade);
            for (String className : classes) {
                TreeNode classNode = new TreeNode(className);
                gradeNode.addChild(classNode);
                List<String> courses = classData.get(className);
                for (String course : courses) {
                    TreeNode courseNode = new TreeNode(course);
                    classNode.addChild(courseNode);
                }
            }
        }

        // 打印树形结构
        printTree(root, 0);
    }

    private static void printTree(TreeNode node, int depth) {
        StringBuilder indent = new StringBuilder();
        for (int i = 0; i < depth; i++) {
            indent.append("  ");
        }
        System.out.println(indent + node.getName());
        for (TreeNode child : node.getChildren()) {
            printTree(child, depth + 1);
        }
    }
}

以上示例代码将List年级、班级和课程数据转换为一个树形结构，并打印出来。您可以根据实际情况修改数据结构和打印方式。