Question

我正在为一个应用程序编写代码，该应用程序可以跟踪学生在校园自助餐厅购买食物的情况。有两个类 - 学生，它包含重载的构造函数和＆amp;适当的吸气剂二传手法;和 MealCard ，它包含一个类变量来跟踪发出的餐卡数量，适当的吸气剂和放大器数量。 setter方法，purchaseItem（）方法，purchasePoints（）方法＆amp;重写的toString（）方法。还有一个 Tester 类。

在我的 MealCard 课程中，这些方法是在 Tester 中编写的，当我打电话给他们时，它们无法正常工作。我想从用户那里获取itemValue但是如何在 MealCard 类中执行此操作？

对于purchasePoints方法，我如何从 MealCard 类中获取用户的topUpValue？

到目前为止，

代码是：

public class Student {

// Instance Variables
private String name;
private int age;
private String address;

// Default Constructor
public Student() {
    this("Not Given", 0, "Not Given");
}

// Parameterized constructor that takes in values
public Student(String name, int age, String address) {
    this.name = name;
    this.age = age;
    this.address = address;
}

// Getters and Setters
public String getName() {
    return name;
}
public void setName(String name) {
    this.name = name;
}

public int getAge() {
    return age;
}
public void setAge(int age) {
    this.age = age;
}

public String getAddress(){
    return address;
}
public void setAddress(String address) {
    this.address = address;
}

// toString() to be overriden
@Override
public String toString() {
    return "Name: " + this.name + "\n" + "Age: " + this.age + "\n" + "Address: " + this.address;
}
}

`

public class MealCard extends Student {

static int numberOfMealCards;
private final static int DEFAULT_BALANCE = 1000;
private int itemValue;
private int topUpValue;
public int newBalance;

// Getters and Setters
public int getItemValue() {
    return itemValue;
}
public void setItemValue(int itemValue) {
    this.itemValue = itemValue;
}

public int getTopUpValue() {
    return topUpValue;
}
public void setTopUpValue(int topUpValue) {
    this.topUpValue = topUpValue;
}

// purchaseItem method for when students buy food
public int purchaseItem() {
    newBalance = DEFAULT_BALANCE - itemValue;
    return newBalance;
}

// purchasePoints method for students topping up their meal card balance
public int purchasePoints() {
    newBalance = DEFAULT_BALANCE + topUpValue;
    return newBalance;
}

// Overriden toString method
@Override
public String toString() {
    return super.toString() + "Meal Card Balance: " + this.newBalance + "\n" + "Number of Meal Cards: " + numberOfMealCards;
}

}

`

import java.util.Scanner;

public class TestMealCard {

public static void main(String[] args) {

    // Create instances of MealCard class
    MealCard student1 = new MealCard();
    MealCard student2 = new MealCard();

    Scanner keyboard = new Scanner(System.in);

    System.out.println("Name: ");
    student1.setName(keyboard.nextLine()); 
    System.out.println("Age: ");
    student1.setAge(keyboard.nextInt()); 
    System.out.println("Address: ");
    student1.setAddress(keyboard.nextLine()); 
    System.out.println("Meal Card Balace: ");
    student1.newBalance = keyboard.nextInt();
    System.out.println("Number of Meal Cards Issued: ");
    student1.numberOfMealCards = keyboard.nextInt();

    System.out.println("Name: ");
    student2.setName(keyboard.nextLine()); 
    System.out.println("Age: ");
    student2.setAge(keyboard.nextInt()); 
    System.out.println("Address: ");
    student2.setAddress(keyboard.nextLine()); 
    System.out.println("Meal Card Balace: ");
    student2.newBalance = keyboard.nextInt();
    System.out.println("Number of Meal Cards Issued: ");
    student2.numberOfMealCards = keyboard.nextInt();

    // Call purchaseItem
    student1.purchaseItem();


    // Call purchasePoints
    student2.purchasePoints();

    // Call tString to output information to user
}
}

Answer 1

为了从用户设置itemValue，您需要使用此setItemValue（）方法从用户获取该输入。

实施例

System.out.print("Please enter the item value:   ");
student1.setItemValue(keyboard.nextInt());

或

int itemVal = 0;
System.out.print("Please enter the item value:   ");
itemVal = keyboard.nextInt();
student1.setItemValue(itemVal);

至于其他方法调用只需调用setUfor toUpValue。

实施例

System.out.print("Please enter the item value:   ");
student1.setTopUpValue(keyboard.nextInt());

或

int toUpVal = 0;
System.out.print("Please enter the item value:   ");
itemVal = keyboard.nextInt();
student1.setTopUpValue(topUpVal);

希望有帮助=）。

从不同的类调用方法| Java的

1 个答案: