java - 接受输入、进行计算并显示答案

Question

所以我正在尝试用java编写一个基本程序。它接受输入，对输入进行计算并显示结果。它有 3 个构造函数，第一个构造函数不接受输入并创建错误消息，第二个和第三个构造函数接受输入并对其执行计算。

所以程序应该接受(来自创建者类):

订单o1 = new Order("车牌号码", 12.7, 6)

程序确实接受上述代码，但不执行任何计算，仅显示“新订单”。

不确定我在这里做错了什么，我添加了评论来尝试解释我在做什么。

public class Order {
private static int orderNum = 0;
public Order(){
    orderNum++;                 //setting the static variable
}

private String productName;
public double price;
private double discount;
public double quantity;
public double total;
private String message;
private boolean isDiscounted = false;
private boolean isValidOrder = true;

//setting the instance variables and booleans


public boolean isDiscounted(){          //setting the valid
discount boolean value
    if (discount > 100 || discount ==0) {
        return false;
    }
    else {
        return true;
    }
}

public boolean isValidOrder(){      //setting the valid order boolean value
    if (total ==0){
        return false;
    }
    else {
        return true;
    }
}

public Order(String m) {
    orderNum++;
    this.message = m;
    isValidOrder = false;
    isDiscounted = false;
}
//first constructor accepting no parameters, with boolean values set

public Order(String pN, double p, int q) {
    orderNum++;
    this.productName = pN;
    this.price = p;
    this.quantity = q;
    isValidOrder = true;
    isDiscounted = false;
}
//second constructor accepting 3 parameters, with boolean values set

public Order(String pN, double p, double d, int q) {
    orderNum++;
    this.productName = pN;
    this.price = p;
    this.discount = d;
    this.quantity = q;
    isValidOrder = true;
    isDiscounted = true;
}
//third constructor accepting 4 parameters, with boolean values set

    public void setTotal(double t){
        total = t;
        isDiscounted = true;
    }

//setting the total



public double getTotal(){
    if (isValidOrder == true){
        return ((price * quantity)-(price * quantity * (discount/100)));
    }
    else if (isDiscounted == false){
        return (price * quantity);
    }
    return total;
}
//getting the total and calculations



@Override
public String toString(){
    if (isDiscounted == true){
        message = ("Order number: " + Order.orderNum + "\nProduct
 Name: " + productName
                + "\nProduct Price: " + price + "\nOrder Quantity:
 " + quantity
                + "\nDiscount: " + discount + "\nTotal Price: " + total);
        }

    //first part of toString method, with discount
    else if (isDiscounted == false){
        message = ("Order number: " + Order.orderNum + "\nProduct
 Name: " + productName
                + "\nProduct Price: " + price + "\nOrder Quantity:
" + quantity
                + "\nTotal Price: " + total);
    }
    //second part of toString method, with no discount
    else if (isValidOrder == false){
        message = "Error";
    }
    //third part of toString method with error message
    return message;
 }

}

Answer 1

我修改了你的代码，检查一下。

public class Order {
private static int orderNum = 0;
public Order(){
orderNum++;                 //setting the static variable
}
private String productName;
public double price;
private double discount;
public double quantity;
public double total;
private String message;
private boolean isDiscounted = false;
private boolean isValidOrder = true;

//setting the instance variables and booleans


public boolean isDiscounted() {          //setting the discount boolean 
    if (discount > 100 || discount == 0) {
        return false;
    } else {
        return true;
    }
}

public boolean isValidOrder() {      //setting the valid order boolean value
    if (total == 0) {
        return false;
    } else {
        return true;
    }
}

public Order(String m) {
    orderNum++;
    this.message = m;
    isValidOrder = false;
    isDiscounted = false;
}
//first constructor accepting no parameters, with boolean values set

public Order(String pN, double p, int q) {
    orderNum++;
    this.productName = pN;
    this.price = p;
    this.quantity = q;
    isValidOrder = true;
    isDiscounted = false;
}
 //second constructor accepting 3 parameters, with boolean values set

public Order(String pN, double p, double d, int q) {
    orderNum++;
    this.productName = pN;
    this.price = p;
    this.discount = d;
    this.quantity = q;
    isValidOrder = true;
    isDiscounted = true;
}
 //third constructor accepting 4 parameters, with boolean values set

public void setTotal(double t) {
    total = t;
    isDiscounted = true;
}

//setting the total


public double getTotal() {
    if (isValidOrder == true) {
        return ((price * quantity) - (price * quantity * (discount / 100)));
    } else if (isDiscounted == false) {
        return (price * quantity);
    }
    return total;
}
 //getting the total and calculations


@Override
public String toString() {
    if (isDiscounted == true) {
        message = ("Order number: " + Order.orderNum + " \n Product Name: "
                + productName + "\nProduct Price: " + price + "\nOrder Quantity: " + quantity +
                "\nDiscount: " + discount + "\nTotal Price: " + total);
    }

    //first part of toString method, with discount
    else if (isDiscounted == false) {
        message = ("Order number: " + Order.orderNum + "\nProduct Name: " + productName
                + "\nProduct Price: " + price + "\nOrder Quantity:" + quantity
                + "\nTotal Price: " + total);
    }
    //second part of toString method, with no discount
    else if (isValidOrder == false) {
        message = "Error";
    }
    //third part of toString method with error message
    return message;
}

}