组合模式

Composite 组合模式

树状结构专用模式

abstract class Node{
    abstract public void p();
}

class leafNode extendx Node{
    String content;
    public leafNode(String content){
        this.content = content;
    }
    
    public void p(){
        System.out.println(content);
    }
}

class BranchNode extends Node{
    List<Node> nodes = new ArrayList<>();
    String name;
    public BranchNode(String name){
        this.name = name;
    }
}

public class Main{
    public static void main(){
        BranchNode root = new BranchNode('root');
        BranchNode chapter1 = new BranchNode("chapter1");
        BranchNode chapter2 = new BranchNode("chapter2");
        Node c11 = new LeafNode("c11");
        Node c12 = new LeafNode("c12");
        BranchNode b21 = new BranchNode("section21");
        Node c211 = new LeafNode("c211");
        Node c212 = new LeafNode("c212");

        root.add(chapter1);
        root.add(chapter2);
        chapter1.add(cl1);
        chapter2.add(cl2);
        b21.add(c211);
        b21.add(c212);

        tree(root);
    }    
    static void tree(Node b, int depth){
        for(int i = 0; i < depth; i++){
            System.out.println("--");
        }
        b.p();
        if(b instanceof BranchNode){
            for(Node n : ((BranchNode)b).nodes){
                tree(n, depth + 1);
            }
        }
    }
}