Question

您好我正在尝试从链表中确定年份范围，我需要帮助。为了实现这一点，我在我的容器类中有两个名为minYear和maxYear的变量，它们包含subscriptionYears链表。 SubscriptionYear读取当年的年份和细胞数据。类别国家/地区存储国家/地区名称，并且是存储每个国家/地区的年份和移动数据的链接列表subscriptionYear的容器。

minYear设置为9999. maxYear设置为0.每次我添加订阅列表时，我都会更新minYear和maxYear。我使用“minYear”和“maxYear”来检查所请求的订阅期是否有效。如何实现minYear和maxYear来检查所请求的订阅是否有效。

我的班级Subscriptionyear将该特定年份的年份和细胞数据存储为双倍。

//stores the year and statistical subscription data for that year
public class SubscriptionYear {

private int year;
private double subscriptions;
SubscriptionYear next;

public SubscriptionYear(int year,double subscriptions)
{
    setYear(year);
    setSubscription(subscriptions);
    this.next = null;
}
public void setYear(int Year)
{
    this.year= Year;
}
public void setSubscription(double value)
{
    this.subscriptions = value;
}
public int getYear()
{
    return year;
}
public double getSubscription()
{
    return subscriptions;
}
public String toString()
{
    return "Number of Subscriptions: "+subscriptions;
}
public void setNode(SubscriptionYear next)
{
    this.next = next;
}
public SubscriptionYear getNext()
{
    return this.next;
}
}

class Country：我的类Country存储国家/地区的名称，并为susbcriptionYear的链接列表充当容器，其中包含该国家/地区的年份和统计信息。我能够创建列表并成功打印列表，但我似乎无法解决上面解决的问题。统计数据从1960年到2012年开始。

public class Country  {

private String countryNames;
private SubscriptionYear subscriptions;
private int minYear;
private int maxYear;

public Country(String country)
{
    this.countryNames = country;
    this.subscriptions = null;
    this.maxYear = 0;
    this.minYear = 9999;
    }

//adds the subscription and updates the minYear and maxYear
//Dont think i set up the minYear and maxYear correctly.
public void addSubscriptionYear(int year, double subscription)
{
    SubscriptionYear newNode = new SubscriptionYear(year, subscription);
    if(this.isEmpty())
    {
        newNode.setNode(subscriptions);
        subscriptions = newNode;
        if(newNode.getYear()==1960)
        {
            this.minYear++;
        }
    }
    else{
        SubscriptionYear current = subscriptions;
        while(current.getNext()!=null)
        {
            if(current.getYear()==1960)
            {
                this.minYear++;
            }
           else if(current.getYear()==2012)
           {
              this.maxYear++
           }
         current = current.getNext();
        }
        current.setNode(newNode);   
    }
}

//overrides the toString method and prints out the countries.
public String toString()
{
    String result="";
    result += "\n"+this.countryNames;
    SubscriptionYear current = subscriptions;
    while(current!=null)
    {
        result+="\t"+current.getSubscription();
        current = current.getNext();        
    }
    return result;
}
 //returns countryName
  public String getName()
{
    return this.countryNames;
}
public boolean isEmpty()
{
    return (subscriptions == null);
}
}

Answer 1

由于您的分配中存在约束，Country对象必须使用minYear=9999和maxYear=0进行实例化，因此您可以更新Country.addSubscription()方法以执行比较和验证。

所以这样的事情应该有效：

public void addSubscriptionYear(int year, double subscription) {
  // check if this new node's year is within the valid range
  if(year > 2012 || year < 1960)
    throw new IllegalArugmentException("New node's year is not within the 1960 and 2012 range"); // or however else you want to handle this

  // check if this new node has a year earlier than this.minYear
  this.minYear = this.minYear > year ?  year : this.minYear;

  // check if this new node has a year late than this.maxYear
  this.maxYear = this.maxYear < year ? year : this.maxYear;

  SubscriptionYear newNode = new SubscriptionYear(year, subscription);
  if(this.isEmpty()) {
    newNode.setNode(subscriptions);
    subscriptions = newNode;
  }
  else{
    SubscriptionYear current = subscriptions;
    while(current.getNext()!=null)          
      current = current.getNext();
    current.setNode(newNode);   
  }
}

每次添加新节点时，我们都会检查新年度是否小于this.minYear或大于this.maxYear。如果是，我们会相应地调整this.minYear和this.maxYear。

Answer 2

在addSubscriptionYear方法的某个地方，你需要这样的东西。

if (year < minYear) {
    minYear = year;
}

if (year > maxYear) {
    maxYear = year;
}

这样，如果您发现的订阅的年份早于您已找到的最早订阅，则会调整minYear;如果您发现的订阅年晚于您已找到的最新订阅，则会调整maxYear。

你的程序中也有一些错误;但我敢肯定，如果你继续努力，你将设法找到并删除它们。

确定链表中的年份范围

2 个答案: