Java简单类——一对多映射（省、市）-优快云博客

本文通过一个具体的Java程序示例展示了省份与城市之间的对象关联关系。创建了Province和City两个类，Province类中包含了一个City对象数组，用于表示一个省份拥有的多个城市。每个City对象都关联了一个Province对象，表示其所属省份。

 1 class Province {
 2     private int pid ;
 3     private String name ;
 4     private City cities [] ;
 5     public Province (int pid,String name) {
 6         this.pid = pid ;
 7         this.name = name ;
 8     }
 9     public void setCities(City cities[] ){
10         this.cities = cities ;
11     }
12     public City[] getCities() {
13         return this.cities ;
14     }
15     public String getInfo() {
16         return "省份编号：" + this.pid + "，名称：" + this.name ;
17     }
18 }
19 class City {
20     private int cid ;
21     private String name ;
22     private Province province ;
23     public City (int cid,String name) {
24         this.cid = cid ;
25         this.name = name ;
26     }
27     public void setProvince(Province province){
28         this.province = province ;
29     }
30     public Province getProvince() {
31         return this.province ;
32     }
33     public String getInfo() {
34         return "城市编号：" + this.cid + "，名称：" + this.name ;
35     }
36 }
37 public class TestPC{
38     public static void main(String args[]){
39         Province pro = new Province (1,"湖北");
40         City c1 = new City (1001,"武汉") ;
41         City c2 = new City (1002,"孝感") ;
42         City c3 = new City (1003,"宜昌") ;
43         City c4 = new City (1004,"黄石") ;
44         c1.setProvince(pro) ;
45         c2.setProvince(pro) ;
46         c3.setProvince(pro) ;
47         c4.setProvince(pro) ;
48         pro.setCities(new City [] {c1,c2,c3,c4}) ; //一个省份有多个城市
49         System.out.println(c2.getProvince().getInfo()) ;
50         for (int x = 0 ;x < pro.getCities().length ;x ++ ){
51             System.out.println("\t|-" + pro.getCities()[x].getInfo()) ;
52         }
53     }
54 }