java处理树形结构，即父子级

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最新推荐文章于 2025-04-11 19:27:13 发布

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分类专栏： java基础

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本文详细介绍了如何在Java中处理树形结构数据，包括父子级关系的建立、遍历和操作。通过实例代码展示了如何构建和操作树节点，以及在实际应用中如何维护和查询树结构。

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package com.jzb.auth;

import net.sf.json.JSONObject;

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

/**
 * @Description:
 * @Author dell
 * @Version 1.0
 * @Since 1.0
 * @Date: 2019/8/15 18:10
 */
public class test {
    public static void main(String[] args) {
        // get datas
        List<Map<String, Object>> records = getRecords();
        Map<String, Map<String, Object>> tree = new HashMap<>();

        // init head data
        Map<String, Object> head = new HashMap<>();
        head.put("id", "00000");
        head.put("children", new ArrayList<Map<String, Object>>());
        tree.put("00000", head);

        for (int i = 0, l = records.size(); i < l; i++) {
            Map<String, Object> record = records.get(i);
            String parentId = record.get("parentid").toString();

            // set default childern
            record.put("children", new ArrayList<Map<String, Object>>());
            if (tree.containsKey(parentId)) {
                // add children
                @SuppressWarnings("unchecked")
                List<Map<String, Object>> children = (List<Map<String, Object>>) tree.get(parentId).get("children");
                children.add(record);

                // add record
                tree.put(record.get("id").toString(), record);
            } else {
                // TODO other
            }
        }
        JSONObject result = new JSONObject();
        result.putAll(tree.get("00000"));
        System.out.println(result.toString());
    } // End main

    private static List<Map<String, Object>> getRecords() {
        List<Map<String, Object>> result = new ArrayList<>();

        // first record
        Map<String, Object> red01 = new HashMap<>();
        red01.put("id", "U0001");
        red01.put("name", "zhengsan");
        red01.put("parentid", "00000");
        result.add(red01);

        Map<String, Object> red02 = new HashMap<>();
        red02.put("id", "U0002");
        red02.put("name", "lisi");
        red02.put("parentid", "00000");
        result.add(red02);

        Map<String, Object> red0101 = new HashMap<>();
        red0101.put("id", "U0003");
        red0101.put("name", "wangwu");
        red0101.put("parentid", "U0001");
        result.add(red0101);

        Map<String, Object> red0102 = new HashMap<>();
        red0102.put("id", "U0004");
        red0102.put("name", "zhaolu");
        red0102.put("parentid", "U0001");
        result.add(red0102);

        Map<String, Object> red010101 = new HashMap<>();
        red010101.put("id", "U0005");
        red010101.put("name", "maqi");
        red010101.put("parentid", "U0003");
        result.add(red010101);

        Map<String, Object> red010102 = new HashMap<>();
        red010102.put("id", "U0006");
        red010102.put("name", "chenba");
        red010102.put("parentid", "U0003");
        result.add(red010102);

        return result;
    }

}