1.java基础- java List 转 tree （树形结构）

原理就是回调函数，迭代

public class TreeNode {

    private String id;
    private String pid;
    private String name;
    private List<TreeNode> children = new ArrayList<>();

    public TreeNode() {

    }

    public TreeNode(String id, String pid, String name) {
        this.id = id;
        this.pid = pid;
        this.name = name;
    }

    public String getId() {
        return id;
    }

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

    public String getPid() {
        return pid;
    }

    public void setPid(String pid) {
        this.pid = pid;
    }

    public String getName() {
        return name;
    }

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

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

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

}

private List<TreeNode> buildTree(List<TreeNode> nodeList){
        List<TreeNode> result = new ArrayList<>();
        for (TreeNode zone:nodeList) {
            if (zone.getPid().equals("0")) {
                result.add(zone);
                setChildren(nodeList, zone);
            }
        }
        return result;
    }

    public static void setChildren(List<TreeNode> list, TreeNode parent) {
        for (TreeNode zone: list) {
            if(parent.getId().equals(zone.getPid())){
                parent.getChildren().add(zone);
            }
        }
        if (parent.getChildren().isEmpty()) {
            return;
        }
        for (TreeNode zone: parent.getChildren()) {
            setChildren(list, zone);
        }
    }