Java简单类——双向一对多映射

 class Item {     // 父栏目
     private int iid ;
     private String name ;
     private String note ;
     private Subitem subitems [] ; //一个父栏目下有多个子栏目
     private Product products [] ; //一个栏目下包含多个商品
     public Item(int iid,String name,String note) {
         this.iid = iid ;
         this.name = name ;
         this.note = note ;
     }
     public void setSubitems(Subitem subitems[]) {
         this.subitems = subitems ;
     }
     public void setProducts(Product[] products) {
         this.products = products ;
     }
     public Product[] getProducts() {
         return this.products ;
     }
     public Subitem [] getSubitems() {
         return this.subitems ;
     }
     public String getInfo() {
         return "栏目编号：" + this.iid + "，名称：" + this.name + "，描述：" + this.note ;
     }
 }
 class Subitem {  // 子栏目
     private int sid ;
     private String name ;
     private String note ;
     private Item item ; // 一个子栏目对应一个父栏目
     private Product products [] ; //一个子栏目下包含多个商品
     public Subitem(int sid,String name,String note) {
         this.sid = sid ;
         this.name = name ;
         this.note = note ;
     }
     public void setItem(Item item) {
         this.item = item ;
     }
     public Item getItem() {
         return this.item ;
     }
     public void setProducts(Product products[]) {
         this.products = products ;
     }
     public Product[] getProducts() {
         return this.products ;
     }
     public String getInfo() {
         return "子栏目编号：" + this.sid + "，名称：" + this.name + "，描述：" + this.note ;
     }
 }
 class Product {  // 商品
     private int pid ;
     private String name ;
     private double price ;
     private Item item ;
     private Subitem subitem ;
     public Product(int pid,String name,double price) {
         this.pid = pid ;
         this.name = name ;
         this.price = price ;
     }
     public void setItem(Item item) {
         this.item = item ;
     }
     public Item getItem() {
         return this.item ;
     }
     public void setSubitem(Subitem subitem) {
         this.subitem = subitem ;
     }
     public Subitem getSubitem() {
         return this.subitem ;
     }
     public String getInfo() {
         return "商品编号：" + this.pid + "，名称：" + this.name + "，价格：" + this.price ;
     }
 }
 public class TestISP {
     public static void main(String args[]){
         //准备出单独的类对象
         Item item = new Item(1,"文具","-") ;
         Subitem suba = new Subitem(1001,"笔","-") ;
         Subitem subb = new Subitem(1002,"尺","-") ;
         Subitem subc = new Subitem(1003,"刀","-") ;
         Product proa = new Product(90001,"中性笔",2.0) ;
         Product prob = new Product(90002,"钢笔",10.0) ;
         Product proc = new Product(90003,"毛笔",8.0) ;
         Product prod = new Product(90004,"直尺",2.0) ;
         Product proe = new Product(90005,"三角尺",1.5) ;
         Product prof = new Product(90006,"美工刀",5.0) ;
         Product prog = new Product(90007,"剪刀",6.0) ;
         //设置类之间的引用关系
         suba.setItem(item) ;
         subb.setItem(item) ;
         subc.setItem(item) ;
         item.setSubitems(new Subitem[]{suba,subb,subc}) ;
         proa.setSubitem(suba) ;
         proa.setItem(item) ;
         prob.setSubitem(suba) ;
         prob.setItem(item) ;
         proc.setSubitem(suba) ;
         proc.setItem(item) ;
         prod.setSubitem(subb) ;
         prod.setItem(item) ;
         proe.setSubitem(subb) ;
         proe.setItem(item) ;
         prof.setSubitem(subc) ;
         prof.setItem(item) ;
         prog.setSubitem(subc) ;
         prog.setItem(item) ;
         suba.setProducts(new Product[] {proa,prob,proc}) ;
         subb.setProducts(new Product[] {prod,proe}) ;
         subc.setProducts(new Product[] {prof,prog}) ;
         item.setProducts(new Product[] {proa,prob,proc,prod,proe,prof,prog}) ;
         //取出数据
         //1、通过一个类型找到全部的子类型
         System.out.println(item.getInfo()) ;
         for (int x = 0;x <item.getSubitems().length ;x ++ ){
             System.out.println("\t|-" + item.getSubitems()[x].getInfo()) ;
         }
         System.out.println("--------------------------------------------------------------") ;
         System.out.println(item.getInfo()) ;
         for (int x = 0;x <item.getProducts().length ;x ++ ){
             System.out.println("\t|-" + item.getProducts()[x].getInfo()) ;
             System.out.println("\t|-" + item.getProducts()[x].getSubitem().getInfo()) ;
         }
         System.out.println("--------------------------------------------------------------") ;
         System.out.println(subb.getInfo()) ;
         for (int x = 0;x <subb.getProducts().length ;x ++ ){
             System.out.println("\t|-" + subb.getProducts()[x].getInfo()) ;
         }
     }
 }

第一次写上百行的代码啊QAQ，中间报错了几次折腾了好久才发现是尼玛设定set和get方法时竟然不知道怎么的把public写成了private，晕死，以后就知道了。错误如下图

最终完成时运行结果如下