import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;
import javax.swing.tree.TreeNode;


public class TreePrint {
	
    public static void main(String[] args) {
        
        Tree<String> rootFolder = new Tree<>("RootFolder"); 
        
        Node<String> video = new Node<>("Video"); 
        
        Node<String> music = new Node<>("Music"); 
        Node<String> picture = new Node<>("Picture");
        rootFolder.add(video);// вот отсюда начиная
        rootFolder.add(music);
        rootFolder.add(picture);
        Node<String> terminator = new Node<>("Terminator", video);
        Node<String> dieHard = new Node<>("Die Hard", video);
        Node<String> rocky = new Node<>("Rocky", video);
        Node<String> abby = new Node<>("Abba", music);
        video.add(terminator);
        video.add(dieHard);
        video.add(rocky);
        music.add(abby);
        Node<String> homePicture = new Node<>("Home picture", picture);
        Node<String> workPicture = new Node<>("Work picture", picture);
        picture.add(homePicture);
        picture.add(workPicture);

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package tree;

import java.util.ArrayList;
import java.util.List;

public class Node<T> {

    private T data = null;
    private List<Node<T>> children = new ArrayList<>();
    private Node parent = null;

    public Node(T data) {
        this.data = data;
    }

    public void addChild(T data) {
        Node<T> node = new Node<>(data);        
        node.parent = this;
        children.add(node);
    }
   
    
     public void remove(T data) {
        Node<T> node = new Node<>(data);        
        node.parent = this;
        children.remove(node);
     }

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

    public Node getParent() {
        return parent;
    }

    
    public T getData() {
        return data;
    }

    public void setData(T data) {
        this.data = data;
    }

}

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package tree;

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;
import javax.swing.tree.TreeNode;


public class TreePrint {
	
    public static void main(String[] args) {
        
        Tree<String> rootFolder = new Tree<>("RootFolder"); 
        
        Node<String> video = new Node<>("Video"); 
        Node<String> music = new Node<>("Music"); 
        Node<String> picture = new Node<>("Picture");
        
        video.addChild("Terminator");
        video.addChild("Die Hard");
        video.addChild("Rocky");
        music.addChild("Eminem");
        picture.addChild("Picasso");
        
        
        
    }
    
        
        
    

    private static <T> void printCatalog() {

        printNode(rootFolder.getRoot()); // Вот здесь ругается
        List<Node<T>> kids = rootFolder.iterate(); // Вот здесь ругается
        printTree(kids);

    }

    private static <T> void printTree(List<Node<T>> kids) {
        if (kids.isEmpty()) {
            return;
        }
        for (Node<T> kid : kids) {
            printNode(kid);
            printTree(kid.getChildren());
        }

    }

    private static <T> void printNode(Node<T> kid) {
        System.out.println(kid.getData());

    }

}

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package tree;

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;
import javax.swing.tree.TreeNode;


public class TreePrint {
	
    public static void main(String[] args) {
        
        Tree<String> rootFolder = new Tree<>("RootFolder"); 
        
        Node<String> video = new Node<>("Video"); 
        Node<String> music = new Node<>("Music"); 
        Node<String> picture = new Node<>("Picture");
        
        video.addChild("Terminator");
        video.addChild("Die Hard");
        video.addChild("Rocky");
        music.addChild("Eminem");
        picture.addChild("Picasso");
        
        printCatalog(rootFolder);
        
    }
    
    private static <T> void printCatalog(Tree<T> rootFolder) {
        
        printNode(rootFolder.getRoot());
        List<Node<T>> kids = rootFolder.iterate();
        printTree(kids);

    }

    private static <T> void printTree(List<Node<T>> kids) {
        if (kids.isEmpty()) {
            return;
        }
        for (Node<T> kid : kids) {
            printNode(kid);
            printTree(kid.getChildren());
        }

    }

    private static <T> void printNode(Node<T> kid) {
        System.out.println(kid.getData());

    }

}

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package tree;

import java.util.List;

class Tree<T> {

    private Node<T> root = null;
    
    public Tree(T data) {
        root = new Node(data);
    }
    
    public Node getRoot() {
        return root;
    }

    <T> List<Node<T>> iterate() {
        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }
}
	

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package tree;

import java.util.ArrayList;
import java.util.List;

public class Node<T> {

    private T data = null;
    private List<Node<T>> children = new ArrayList<>();
    private Node parent = null;

    public Node(T data) {
        this.data = data;
    }

    public void addChild(T data) {
        Node<T> node = new Node<>(data);        
        node.parent = this;
        children.add(node);
    }
    public List<Node<T>> iterate() {
            return children;
        }
    
    
     public void remove(T data) {
        Node<T> node = new Node<>(data);        
        node.parent = this;
        children.remove(node);
     }

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

    public Node getParent() {
        return parent;
    }

    
    public T getData() {
        return data;
    }

    public void setData(T data) {
        this.data = data;
    }

}

Node<String> video = new Node<>("Video", rootFolder.getRoot()); 
        Node<String> music = new Node<>("Music", rootFolder.getRoot());
        Node<String> picture = new Node<>("Picture", rootFolder.getRoot());

("Video", rootFolder.getRoot());

Node<String> video = new Node<>("Video");
        Node<String> music = new Node<>("Music");
        Node<String> picture = new Node<>("Picture");
        rootFolder.getRoot().addChild(video);
        rootFolder.getRoot().addChild(music);
        rootFolder.getRoot().addChild(picture);

        video.addChild(new Node<>("Terminator"));
        video.addChild(new Node<>("Die Hard"));
        video.addChild(new Node<>("Rocky"));
        music.addChild(new Node<>("Eminem"));
        picture.addChild(new Node<>("Picasso"));

/*

import java.util.ArrayList;

import java.util.List;


import java.util.ArrayList;
import java.util.List;

public class Node<T> {

    private T data;
    private final List<Node<T>> children = new ArrayList<>();

    public Node(T data) {
        this.data = data;
    }

    public Node<T> addChild(Node<T> node) {
        children.add(node);
        return node;
    }

    public Node<T> addChild(T data) {   
        
        ????????????????????????????????????????????????????????????????
???????????????????????????????????????????
    }
    
    public List<Node<T>> iterate() {
        return children;
    }

    public void remove(Node<T> node) {
        children.remove(node);
    }

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

    public T getData() {
        return data;
    }

    public void setData(T data) {
        this.data = data;
    }
}

public class TreePrint {

    public static void main(String[] args) {

        Tree<String> rootFolder = new Tree<>("RootFolder");

        Node<String> rootNode = rootFolder.getRoot();
        
        Node<String> video = new Node<>("Video");
        Node<String> music = new Node<>("Music");
        Node<String> picture = new Node<>("Picture");
        
        rootNode.addChild(video);
        rootNode.addChild(music);
        rootNode.addChild(picture);

        video.addChild(new Node<>("Terminator"));
        video.addChild(new Node<>("Die Hard"));
        video.addChild(new Node<>("Rocky"));
        music.addChild(new Node<>("Eminem"));
        picture.addChild(new Node<>("Picasso"));
        
        
        
        Tree<String> rootFolder1 = new Tree<>("RootFolder1");
        
        
        printCatalog(rootFolder);

    }

    private static <T> void printCatalog(Tree<T> rootFolder) {
        printNode(rootFolder.getRoot());
        List<Node<T>> kids = rootFolder.iterate();
        printTree(kids);
    }

    private static <T> void printTree(List<Node<T>> kids) {
        if (kids.isEmpty()) {
            return;
        }
        for (Node<T> kid : kids) {
            printNode(kid);
            printTree(kid.getChildren());
        }
    }

    private static <T> void printNode(Node<T> kid) {
        System.out.println(kid.getData());

    }
}

   public void addChild(T data) {
        Node<T> node = new Node<>(data);        
        node.parent = this;
        children.add(node);
    }

public void addChild(T data) {
        Node<T> node = new Node<>(data);        
        node.parent = this;
        children.add(node);
    }

public Node<T> addChild(T data) {
вот такой метод??
}

 public Node<T> addChild(T data) {   
        addChild(new Node<>(data));
        return null;
    }