我现在已经编写好几个小时来完成我的任务。现在我已经完成了，我想添加一种方法来对客户的价值进行排序。因此，客户2排在首位，最后排名第5位。我该怎么做？
以下是第一堂课的代码：
public class Customer {
private int customerNumber;
private int purchases;
private int shippingCost;
private int productPrice;
public int getProductPrice() {
return productPrice;
}
public void setProductPrice(int productPrice) {
this.productPrice = productPrice;
}
public int getPurchases() {
return purchases;
}
public Customer(int purchases, int shippingCost, int productPrice) {
this.purchases = purchases;
this.shippingCost = shippingCost;
this.productPrice = productPrice;
}
public void setPurchases(int purchases) {
this.purchases = purchases;
}
public int getShippingCost() {
return shippingCost;
}
public void setShippingCost(int shippingCost) {
this.shippingCost = shippingCost;
}
protected int calculateValue() {
int value=purchases*(productPrice-shippingCost);
return value;
}
public int getCustomerNumber() {
return customerNumber;
}
public void setCustomerNumber(int customerNumber) {
this.customerNumber = customerNumber;
}
第二节课：
public class Subscriber extends Customer{
private int years;
private int fee;
public Subscriber(int purchases, int shippingCost, int productPrice) {
super(purchases, shippingCost, productPrice);
}
public Subscriber(int purchases, int shippingCost,
int productPrice,int _years,int _fee) {
super(purchases, shippingCost, productPrice);
years=_years;
fee=_fee;
}
public int getYears() {
return years;
}
public void setYears(int years) {
this.years = years;
}
public int getFee() {
return fee;
}
public void setFee(int fee) {
this.fee = fee;
}
protected int calculateSubscriptionValue() {
return years*fee;
}
protected int calculateValue(){
int value=super.calculateValue();
value+=calculateSubscriptionValue();
return value;
}
第三课：
public class BusinessSubscriber extends Subscriber{
public BusinessSubscriber(int purchases, int shippingCost, int productPrice, int _years, int _fee) {
super(purchases, shippingCost, productPrice, _years, _fee);
}
private double supportCost;
private double supportTime;
public double getSupportCost() {
return supportCost;
}
public void setSupportCost(double supportCost) {
this.supportCost = supportCost;
}
public double getSupportTime() {
return supportTime;
}
public void setSupportTime(double supportTime) {
this.supportTime = supportTime;
}
//override method: // skriv över den // problem med denna metod. uträkningsfel
protected int calculateValue(){
int value=super.calculateValue();
value+=calculateSubscriptionValue() - calculateSubscriptionValue();
return value;
}
}
最后和主要课程：
public class printValue {
public static void main(String[] args) {
System.out.println("Unsorted version without DataStructure");
System.out.println("-----------------------");
BusinessSubscriber num1 = new BusinessSubscriber(3, 33, 99, 8, 78);
num1.setCustomerNumber(1);
num1.setPurchases(3);
num1.setShippingCost(33);
num1.setYears(8);
num1.setSupportTime(2);
num1.setProductPrice(99);
num1.setFee(78);
num1.setSupportCost(25);
System.out.println("Customer number: " + num1.getCustomerNumber() + " is worth " + num1.calculateValue() + "!");
BusinessSubscriber num2 = new BusinessSubscriber (0, 0, 99, 18, 78);
num2.setCustomerNumber(2);
num2.setPurchases(0);
num2.setShippingCost(0);
num2.setYears(18);
num2.setSupportTime(7);
num2.setProductPrice(99);
num2.setFee(78);
num2.setSupportCost(25);
System.out.println("Customer number: " + num2.getCustomerNumber() + " is worth " + num2.calculateValue() + "!");
BusinessSubscriber num3 = new BusinessSubscriber (0, 0, 99, 8, 78);
num3.setCustomerNumber(3);
num3.setPurchases(0);
num3.setShippingCost(0);
num3.setYears(8);
num3.setSupportTime(0);
num2.setProductPrice(99);
num2.setFee(78);
num2.setSupportCost(25);
System.out.println("Customer number: " + num3.getCustomerNumber() + " is worth " + num3.calculateValue() + "!");
// int purchases, int shippingCost, int productPrice, int _years, int _fee
Subscriber num4 = new Subscriber (12, 33, 99, 5, 78);
num4.setCustomerNumber(4);
num4.setPurchases(12);
num4.setShippingCost(33);
num4.setYears(5);
num4.setProductPrice(99);
num4.setFee(78);
System.out.println("Customer number: " + num4.getCustomerNumber() + " is worth " + num4.calculateValue() + "!");
Customer num5 = new Customer (8, 33, 99);
num5.setCustomerNumber(5);
num5.setPurchases(8);
num5.setShippingCost(33);
num5.setProductPrice(99);
System.out.println("Customer number: " + num5.getCustomerNumber() + " is worth " + num5.calculateValue() + "!");
// sortera efter calculatevalue metoden i businesssubsriber
}
代码的输出：
Customer number: 1 is worth 822!
Customer number: 2 is worth 1404!
Customer number: 3 is worth 624!
Customer number: 4 is worth 1182!
Customer number: 5 is worth 528!
我希望2号客户位于最前面，5位最后，即排序。我怎么做？谢谢。
我试过这个，但那就够了吗？
Integer [] sort = {num1.calculateValue(), num2.calculateValue(), num3.calculateValue(), num4.calculateValue(), num5.calculateValue()};
List<Integer> l1 = Arrays.asList(sort);
Collections.sort(l1);
System.out.println("Values sorted: " + l1);
但更有效的方法是将它全部放在地图中，循环遍历它然后打印它。我怎么做？
此外，我尽可能多地编辑文本，因此看起来并不凌乱。
答案 0 :(得分：0)
如果您根据calculateValue（）对客户进行排序，可以这样做：
Map sortedCustomer= new TreeMap();
sortedCustomer.put(num1.calculateValue(),num1);
sortedCustomer.put(num2.calculateValue(),num2);
sortedCustomer.put(num3.calculateValue(),num3);
sortedCustomer.put(num4.calculateValue(),num4);
sortedCustomer.put(num5.calculateValue(),num5);
//sortedCustomer is in ascending order...reverse it
sortedCustomerDescending =(TreeSet)sortedCustomer.descendingSet();
//get entrySet
Set set = sortedCustomerDescending.entrySet();
// Get an iterator
Iterator i = set.iterator();
// Display elements
while(i.hasNext()) {
Map.Entry me = (Map.Entry)i.next();
//print the entries
System.out.print(me.getKey() + ": ");
System.out.println(me.getValue());
}
答案 1 :(得分：0)
我假设你想按降序排序。
您需要将实现传递给Comaprator并将其传递给Collections#sort方法以及包含要排序的对象的列表。
这应该做的事情
public void testSort() {
List<Customer> cL = Arrays.asList(new Customer(1, 822),
new Customer(2, 1404),
new Customer(3, 624),
new Customer(4, 1182),
new Customer(5, 528));
Collections.sort(cL, new Comparator<Customer>() {
@Override
public int compare(Customer o1, Customer o2) {
return o2.getCalc() - o1.getCalc();
}
});
for( Customer c : cL) {
System.out.println("Customer number: " + c.getCustomerNumber()
+ " is worth " + c.getCalc() + "!");
}
}
输出：
Customer number: 2 is worth 1404!
Customer number: 4 is worth 1182!
Customer number: 1 is worth 822!
Customer number: 3 is worth 624!
Customer number: 5 is worth 528!
为简单起见，我在calc本身添加了一个Customer字段，您可能希望为BusinessSubscriber类实现Comparator，因为您要查找的值来自它
答案 2 :(得分：0)
您的Customer类应实现Comparable接口
public class Customer implements Comparable<Customer>{
您应该覆盖其compareTo方法
@Override
public int compareTo(Customer cus) {
int calculatedValue = cus.calculateValue();
return calculatedValue - this.calculateValue();
}
最后在PrintValue类中，将这些客户添加到ArrayList并使用Collections.sort
ArrayList<Customer> custList = new ArrayList<>();
custList.add(num1);
custList.add(num2);
custList.add(num3);
custList.add(num4);
custList.add(num5);
Collections.sort(custList);
for (Iterator iterator = custList.iterator(); iterator.hasNext();) {
Customer customer = (Customer) iterator.next();
System.out.println("Customer number: " + customer.getCustomerNumber() + " is worth " + customer.calculateValue() + "!");
}
答案 3 :(得分：0)
如果您有对象列表，可以使用Collections.sort对其进行排序。
愚蠢的例子（未编译或运行）：
Collections.sort(listOfUsers, new Comparator<User>() {
@Override
public int compare(User u1, User u2) {
return Integer.compare(u1.getAge(), u2.getAge());
}
});
这种比较可能不完全是你需要做的，但你明白了： - ）