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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 ListchildList;
}
TreeUtils.java
public class TreeUtils {
static Listtrees ;
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(ListtreeList, 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 {
ListmetaTypeList = tree.getChildList();
if (metaTypeList != null && metaTypeList.size() > 0) {
for (Tree meta : metaTypeList) {
recursion(maps, meta);
}
}
}
return tree;
}
}