组合模式

把一组相似的对象当作一个单一的对象。如：树形菜单

java">public class Menu {String name;List<Menu> child;public Menu(String name){this.name = name;child = new ArrayList<>();}public void addChild(Menu menu){child.add(menu);}public void printmMenu(){System.out.println(name);child.forEach(Menu::printmMenu);}
}

测试：

java">public class Main {public static void main(String[] args) {Menu root = new Menu("root");root.addChild(new Menu("child1"));root.addChild(new Menu("child2"));root.printmMenu();}
}