Question

我有父类CompositeDiscount。它有一个链接列表来存储一些dicount。它有两个子类BestForVersityStrategy和BestForStudentStrategy。我在另一个类注册中填充父链表。当我尝试从UI迭代LL时，它给出了折扣列表，但是当我从孩子那里调用它时（即BestForVersity），它显示列表是空的。



package registrationui;
import java.util.LinkedList;
public class CompositeDiscount implements IDiscountStrategy{
    LinkedList<IDiscountStrategy> disList;
    public CompositeDiscount(){
        disList= new LinkedList<>();
    }

    @Override
    public int getDiscount(Registration reg) {
       return 0;
    }
    public void addDiscount(IDiscountStrategy ids){
        disList.add(ids);
    }
}

package registrationui; import java.util.LinkedList; public class CompositeDiscount implements IDiscountStrategy{ LinkedList<IDiscountStrategy> disList; public CompositeDiscount(){ disList= new LinkedList<>(); } @Override public int getDiscount(Registration reg) { return 0; } public void addDiscount(IDiscountStrategy ids){ disList.add(ids); } } 这是父类

package registrationui;
public class BestForStudentStrategy extends CompositeDiscount{


     public int getDisocunt(Registration reg){
        int amount=0;
        for(IDiscountStrategy ids:disList){
           if(ids.getDiscount(reg)>amount){
               amount=ids.getDiscount(reg);
           }
        }
        return amount;
    } 
}

这是儿童班

package registrationui; public class BestForStudentStrategy extends CompositeDiscount{ public int getDisocunt(Registration reg){ int amount=0; for(IDiscountStrategy ids:disList){ if(ids.getDiscount(reg)>amount){ amount=ids.getDiscount(reg); } } return amount; } }

通过调用Resitration class

的控制器从其填充id的UI

private void academicActionPerformed(java.awt.event.ActionEvent evt) {                                         

      if(academic.isSelected())
        rcc.addCompositeDiscount(rcc.getDiscountPloicy("registrationui.AcademicExcellenceDiscount"));
        else{
            for(IDiscountStrategy ids:rcc.getCompositeDisocunt().disList)
            {
                if(ids.getClass().toString().equals("class registrationui.AcademicExcellenceDiscount"))
                    rcc.getCompositeDisocunt().disList.remove(ids);
            }
        }
    }

private void academicActionPerformed(java.awt.event.ActionEvent evt) {                                         

      if(academic.isSelected())
        rcc.addCompositeDiscount(rcc.getDiscountPloicy("registrationui.AcademicExcellenceDiscount"));
        else{
            for(IDiscountStrategy ids:rcc.getCompositeDisocunt().disList)
            {
                if(ids.getClass().toString().equals("class registrationui.AcademicExcellenceDiscount"))
                    rcc.getCompositeDisocunt().disList.remove(ids);
            }
        }
    }



public void addCompositeDiscount(IDiscountStrategy ids){        
       cds.addDiscount(ids);
       bfn=new BestForNsuStrategy();      
       bfs=new BestForStudentStrategy();  
    }

public void addCompositeDiscount(IDiscountStrategy ids){ cds.addDiscount(ids); bfn=new BestForNsuStrategy(); bfs=new BestForStudentStrategy(); }

Answer 1

CompositeDiscount中的链接列表是静态的。 Java中的静态变量不是继承的，它们只存在于声明它们的类中

Answer 2

public static LinkedList<IDiscountStrategy> disList;

您必须使用静态

的公共修饰符

无法访问Parent LinkedList java

2 个答案: