public static void main(String[] args) {
        List<Zone> zones = listWithTree();
        for (Zone zone : zones) {
            System.out.println(zone.getName());
        }
    }

    public static List<Zone> listWithTree() {
        // 1、查出所有分类
        List<Zone> zoneList = new ArrayList<>();

        zoneList.add(new Zone(1,"成都",0));

        zoneList.add(new Zone(2,"南昌",0));

        zoneList.add(new Zone(3,"四川",0));

        zoneList.add(new Zone(4,"绵阳",3));

        zoneList.add(new Zone(5,"天津",3));

        zoneList.add(new Zone(6,"德阳",4));

        zoneList.add(new Zone(7,"西充",1));

        zoneList.add(new Zone(8,"重庆",7));

        // 组装成父子的树形结构
        ArrayList<Zone> result = new ArrayList<>();
        zoneList.stream().filter(m1 ->
                m1.getParentId() == 0
        ).peek(menu -> {
            result.addAll(getChildren(menu, zoneList, 0));
        }).collect(Collectors.toList());
        return result;
    }

    private static List<Zone> getChildren(Zone parent, List<Zone> all, int count){
        System.out.println("id===="+parent.getId()+"===count===="+count);
        List<Zone> list = new ArrayList<>();
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < count; i++) {
            sb.append("  ");
        }
        parent.setName(sb.append(parent.getName()).toString());
        list.add(parent);
        count++;
        int finalCount = count;
        Optional.ofNullable(all).orElse(new ArrayList<>())
                .stream()
                .filter(item -> parent.getId() == item.getParentId())
                .forEach(item -> {
                    List<Zone> subList;
                    if (item.getParentId() == 0){
                        subList = getChildren(item, all, 0);
                    }else{
                        subList = getChildren(item, all, finalCount);
                    }
                    list.addAll(subList);
                });
        return  list;
    }

Zone实体

public class Zone {

    int id;

    String name;

    int parentId;

    List<Zone> children;

    public Zone(int id, String name, int parentId) {

        this.id = id;

        this.name = name;

        this.parentId = parentId;

    }

    public void addChildren(Zone zone){

        if(children == null) {

            children = new ArrayList<>();

        }

        children.add(zone);

    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getParentId() {
        return parentId;
    }

    public void setParentId(int parentId) {
        this.parentId = parentId;
    }

    public List<Zone> getChildren() {
        return children;
    }

    public void setChildren(List<Zone> children) {
        this.children = children;
    }
}