/**
* list tree node
* @Author: zilong
* @Date: 2021/11/25
*/
@Data
public class Node<T> {
private T id;
private T parentId;
}
/**
* tree node
* @Author: zilong
* @Date: 2021/11/24
*/
@Data
public class TreeNode<T, R extends TreeNode> extends Node<T> {
private List<R> children;
}
/**
* list to tree
* @param list list
* @param <R> 具体类型
* @return
*/
public static <R extends TreeNode> List<R> list2Tree(List<R> list) {
Map<Object, R> nodeMap = new HashMap<>();
List<R> headNodes = new ArrayList<>();
List<R> tree = new ArrayList<>();
// 缓存节点
list.forEach(e -> {
nodeMap.put(e.getId(), e);
// 根节点缓存
if (e.getParentId() == null) {
headNodes.add(e);
}
});
// 节点连接到各个根节点上
list.forEach(e -> {
if (e.getParentId() != null) {
if (nodeMap.get(e.getParentId()).getChildren() == null) {
nodeMap.get(e.getParentId()).setChildren(new ArrayList());
}
nodeMap.get(e.getParentId()).getChildren().add(e);
}
});
// 根节点返回
headNodes.forEach(node -> {
tree.add(nodeMap.get(node.getId()));
});
return tree;
}
list转tree
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转载自blog.csdn.net/qq_36514197/article/details/121559435
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