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); } } } }