Java一对多案例及实现

class Item{
    private int iid;//分类编号
    private String title;//名称
    private String note;//简介
    private Subitem[] subitems;//子类数组
    public void setSubitems(Subitem[] subitems){
        this.subitems = subitems;
    }
    public Subitem[] getSubitems(){
        return this.subitems;
    }
    public Item(int iid,String title,String note){
        this.iid = iid;
        this.title = title;
        this.note = note;
    }
    public String getItemInfo(){
        return "分类编号："+this.iid+",名称"+this.title+",简介"+this.note;
    }
}
class Subitem{
    private int sid;//子类编号
    private String title;//名称
    private String note;//简介
    private Item item;
    public void setItem(Item item){
        this.item = item;
    }
    public Item getItem(){
        return this.item;
    }
    public Subitem(int sid,String title,String note){
        this.sid = sid;
        this.title = title;
        this.note = note;
    }
    public String getSubitemInfo(){
        return "子分类编号："+this.sid+",名称："+this.title+",简介："+this.note;
    }
}
public class TestDemo01 {
    public static void main(String[] args) {
        //第一步：根据结构设计关系
        //1、准备出所有独立的对象，本处属于一对多
        Item item = new Item(10,"编程语言","-");
        Subitem subA = new Subitem(1001,"Java","-");
        Subitem subB = new Subitem(1002,"Python","-");
        Subitem subC = new Subitem(1003,"C","-");
        //2、设置彼此的引用关系
        subA.setItem(item);
        subB.setItem(item);
        subC.setItem(item);
        item.setSubitems(new Subitem[]{subA,subB,subC});
        //第二步：根据表结构取出数据
        System.out.println(subA.getSubitemInfo());
        System.out.println("\t|-"+subA.getItem().getItemInfo());
        System.out.println("\n========================================\n");
        for (int x = 0;x<item.getSubitems().length;x++){
            System.out.println(item.getSubitems()[x].getSubitemInfo());
        }
    }
}