Java list如何根据id获取子节点 Java list根据id获取子节点代码

本篇文章小编给大家分享一下Java list根据id获取子节点代码，小编觉得挺不错的，现在分享给大家供大家参考，有需要的小伙伴们可以来看看。

实现思路

1.获取整个数据的list集合数据

2.将数据分组，java8 list有groupby分组，java8之前的自己遍历整理

3.分组后递归获取子节点，有子节点的添加，没有的设置子节点并删除分组的数据，知道分组数据删完

Tree.java

@Data
public class Tree {
  private Integer id;
  private Integer pId;
  private String key;
  private String value;
  private List childList;
}

TreeUtils.java

public class TreeUtils {
  static List trees ;
  static {
    String jsonStr = "[" +
        "{"id":100,"pId":1,"key":"root", "value": "root"}," +
        "{"id":1000,"pId":100,"key":"node1", "value": "node1"}," +
        "{"id":2000,"pId":100,"key":"node2","value": "node2"}," +
        "{"id":3000,"pId":100,"key":"node3","value": "node3"}," +
        "{"id":1100,"pId":1000,"key":"node11","value": "node11"}," +
        "{"id":1200,"pId":1000,"key":"node12","value": "node12"}," +
        "{"id":1110,"pId":1100,"key":"node111","value": "node111"}," +
        "{"id":1120,"pId":1100,"key":"node112","value": "node112"}," +
        "{"id":2100,"pId":2000,"key":"node21","value": "node21"}," +
        "{"id":2200,"pId":2000,"key":"node22","value": "node22"}," +
        "{"id":2110,"pId":2100,"key":"node211","value": "node21"}" +
        "]";
    trees = JSONObject.parseArray(jsonStr, Tree.class);
  }

  public static void main(String[] args) {
    Tree tree = metaTree(trees, 100);
    /**
     * Tree@6073f712[id=100,pId=1,key=root,value=root,childList=[
     *           Tree(id=1000, pId=100, key=node1, value=node1, childList=[
     *             Tree(id=1100, pId=1000, key=node11, value=node11, childList=[
     *               Tree(id=1110, pId=1100, key=node111, value=node111, childList=null),
     *               Tree(id=1120, pId=1100, key=node112, value=node112, childList=null)]),
     *             Tree(id=1200, pId=1000, key=node12, value=node12, childList=null)]),
     *           Tree(id=2000, pId=100, key=node2, value=node2, childList=[
     *             Tree(id=2100, pId=2000, key=node21, value=node21, childList=[
     *               Tree(id=2110, pId=2100, key=node211, value=node21, childList=null)]),
     *               Tree(id=2200, pId=2000, key=node22, value=node22, childList=null)]),
     *           Tree(id=3000, pId=100, key=node3, value=node3, childList=null)]]
     */
    System.out.println("tree:" + ToStringBuilder.reflectionToString(tree));
  }

  private static Tree metaTree(List treeList, Integer id) {
//此处getId getPId根据自己实际情况更改
    Tree treeConfig = treeList.stream().filter(tree -> tree.getId().equals(id)).collect(Collectors.toList()).get(0);
    Map> collect = treeList.stream().filter(type -> type.getPId() != null).collect(Collectors.groupingBy(Tree::getPId));
    if (collect != null && collect.size() > 0) {
      recursion(collect, treeConfig);
    }
    return treeConfig;
  }

  private static Tree recursion(Map> maps, Tree tree) {
    if (tree.getChildList() == null) {
      if (maps.get(tree.getId()) != null) {
        tree.setChildList(maps.get(tree.getId()));
        maps.remove(tree.getId());
        if (maps.size() > 0) {
          recursion(maps, tree);
        }
      }
    } else {
      List metaTypeList = tree.getChildList();
      if (metaTypeList != null && metaTypeList.size() > 0) {
        for (Tree meta : metaTypeList) {
          recursion(maps, meta);
        }
      }
    }
    return tree;
  }
}