chain of respond

Order.java
public class Order {
    private Cart cart;
 
    // auto gen constructor + getter setter
}

BuyApprove.java
public class BuyApprove{
    protected BuyApprove nextApprove;
    
    public void approveOrder(Order order){
        sout("log de biet la dang o day");
        if(this.canApprove(order.cart.getTotalMoney())){
            this.doApprove(order);
        }
    }
    
    public void setNext(Buyapprove buyApprove){
        this.nextApprove = buyApprove;
    }
    
    protected abstract boolean canApprove(float totalMoneyOfCart);
    protected abstract void doApproving(BuyApprove nextApprove);
}

MailApprove.java
public class MailApprove extends BuyApprove{
    @Override
    protected boolean canApprove(float totalMoney){
        return totalMoney <= 10000000;
    }
    
    @Override
    protected void doApproving(Order order){
        return totalMoney <= 10000000;
        System.out.println("Buy request approved for " + order.cart.getTotalMoney() + "by EMAIL");
    }
}

PhoneApprove.java
public class PhoneApprove extends PhoneApprove{
    @Override
    protected boolean canApprove(float totalMoney){
        return totalMoney <= 50000000;
    }
    
    @Override
    protected void doApproving(Order order){
        return totalMoney <= 50000000;
        System.out.println("Buy request approved for " + order.cart.getTotalMoney() + "by PHONE");
    }
}

BuyRequestWorkFlow.java
public class BuyRequestWorkFlow {
 
    public static BuyApprove getApprover() {
        BuyApprove mailapprove = new MailApprove();
        BuyApprove phoneapprove = new PhoneApprove();
 
        mailapprove.setNext(phoneapprove);
        return mailapprove;
    }
}

App.java
public class App {
 
    public static void main(String[] args) {
        BuyRequestWorkFlow.getApprover().approveOrder(new Order(// khởi tạo 1 order ở đây));
    }
}