java8 Steam 构建树结构

1.创建树结构的类

@Data
public class TreeNode {
	
	private Integer id;
	
	private Integer parentId;

	private String name;
	
	private List children;
 
}

2.构建树结构

	public static List getTree(){
		//获取父节点
		List collect = trees.stream().filter(m -> m.getParentId() == 0).map(
		    (m) -> {
		        m.setChildren(getChildrenList(m, trees));
		        return m;
		    }
		).collect(Collectors.toList());
	
		return collect;
	
	}


    
    public static List getChildrenList(TreeNode tree, List list){
        List children = list.stream().filter(item -> Objects.equals(item.getParentId(), tree.getId())).map(
                (item) -> {
                    item.setChildren(getChildrenList(item, list));
                    return item;
                }
        ).collect(Collectors.toList());
        return children;
    }