它希望我返回显示以下输出的“消息”字符串。如果订单有效但未打折，则输出中不需要折扣，但如果订单有效且有折扣，则输出中需要折扣。现在，我已经尝试了一些事情，但我无法弄清楚 =/
getOrderDetails 方法的主要工作是返回消息实例变量。如果订单有效且未打折，则设置消息，以便在使用适当的实例变量返回时显示如下（不带折扣实例变量），如下所示：
- Order number: 1
- Product name: Pencil
- Product Price: $0.6
- Order Quantity: 6
- Total Price: $3.6
如果订单有效且已打折，则更改消息以使其包含折扣实例变量，如下所示：
- Order number: 1
- Product name: Pencil
- Product Price: $0.6
- Order Quantity: 6
- Discount: 10%
- Total Price: $3.24
如果订单无效，则仅返回消息实例变量。
public class Order {
public String productName; //Name
public double price; //Price
public double discount; //Discount
public int quantity; //Quantity
public double total; //Total for the price multiplied with quantity (with or without discount)
public String message; //Message
public boolean isDiscounted = false; //Set to false, but if it's true, the discount comes in
public boolean isValidOrder = true; //Set to true, but if it's false, the Order becomes invalid and Message comes in
public static int orderNum = 0; //Order number set to 0 as default
public void setProductName(String productName) {
this.productName = productName;
}//Set the name
public void setQuantity(int quantity) {
this.quantity = quantity;
}//Set the price
public void setDiscount(double discount) {
this.discount = discount;
}//Set the discount
public void setPrice(double price) {
this.price = price;
}//Set the price
public void setOrderDetails(boolean isValidOrder, boolean isDiscounted) {
this.isValidOrder = isValidOrder;
}//Set the Order Details
public String getProductName() {
return productName;
}//Get the name
public int getQuantity() {
return quantity;
}//Get the price
public double getDiscount() {
return discount;
}//Get the discount
public double getPrice() {
return price;
}//Get the price
public Order() { //Constructor 1
isValidOrder = false;
message = "**ERROR** : Order number cannot be totalled as no details have been supplied.";
orderNum++;
}
public Order(String productName, int quantity){ //Constructor 2
this.productName = productName;
this.quantity = quantity;
getPrice(this.productName);
if(isValidOrder != false){
calculate();
}
orderNum++;
}
public Order(String productName, int quantity, double discount){ //Constructor 3
this.productName = productName;
testQuantity(quantity);
getPrice(productName);
this.discount = discount;
if(isValidOrder != false){
calculate();
}
orderNum++;
}
public String getOrderDetails(){ //Order Details
if(isValidOrder == true && isDiscounted == true){
message = "Order Number: " + orderNum + "\n" + "Product Name: " + productName + "\n" + "Product Price: $" + price + "\n" + "Order Quantity: " + this.quantity + "\n" + "Discount: " + this.discount + "%" + "\n" + "Total Price: $" + total;
}
else if(isValidOrder == true && isDiscounted == false){
message = "Order Number: " + orderNum + "\n" + "Product Name: " + productName + "\n" + "Product Price: $" + price + "\n" + "Order Quantity: " + this.quantity + "\n" + "Total Price: $" + total;
}
return message;
}
public void calculate(){ //Calculate for total
if(this.isDiscounted == false){
total = quantity * price;
}
else {
total = quantity * price - quantity * price * (discount / 100 );
}
}
public void getPrice(String productName){ //Switch so you can find what item ordered and allocate the correct price
switch(productName){
case "Pencil":
this.price = 0.6;
break;
case "Pen":
this.price = 0.3;
break;
case "Ruler":
this.price = 1.2;
break;
case "Pencil Sharpener":
this.price = 0.3;
break;
case "Compass":
this.price = 4.5;
break;
case "Eraser":
this.price = 4.5;
break;
case "Scissors":
this.price = 2.5;
break;
case "Pencil Case":
this.price = 10.0;
break;
default:
this.price = 0.0;
this.isValidOrder = false;
this.message = "**ERROR** : Invalid product name";
break;
}
}
public void testDiscount(double discount) { //Testing for a Discount
if (discount <=0) {
isDiscounted = false;
message = "**ERROR** : The discount rate cannot be lower than or equal to 0.";
}
else if (discount >50) {
isDiscounted = false;
message = "**ERROR** : The discount rate cannot be higher than 50.";
}
else {
this.discount = discount;
this.isDiscounted = true;
}
}
public void testQuantity(int quantity){ //Testing for Quantity
if(quantity <=0) {
isValidOrder = false;
message = "**ERROR** : Invalid quantity. Quantity cannot be 0 or less.";
}
else if (quantity >1000) {
isValidOrder = false;
message = "**ERROR** : Invalid quantity. Quantity cannot be greater than 1000.";
}
else {
isValidOrder = true;
this.quantity = quantity;
}
}
}