java - 确定链表中的年份范围

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，其中包含subscriptionYears链接列表。 SubscriptionYear读取年份和该年份的蜂窝数据。国家类别存储国家名称，是链接列表subscriptionYear的容器，该列表存储每个国家的年份和移动电话数据。

minYear设置为9999。maxYear设置为0。每次我向列表添加订阅时，我都会更新minYear和maxYear。我使用“ minYear”和“ maxYear”来检查请求的订阅期是否有效。我如何实现minYear和maxYear来检查请求的订阅是否有效。

我的课程Subscriptionyear将年份和该特定年份的移动数据存储为两倍。

//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;
}
}

国家（地区）类：我的国家（地区）类存储国家的名称，并充当susbcriptionYear链接列表的容器，其中包含该国家的年份和统计信息。我能够创建列表并成功打印列表，但似乎无法解决上面的问题。统计数据始于1960年至2012年。

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);
}
}

最佳答案

由于分配中存在必须使用Country和minYear=9999实例化maxYear=0对象的约束，因此可以更新Country.addSubscription()方法以执行比较和验证。

所以这样的事情应该工作：

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，我们都会检查新年是否小于this.minYear或大于this.maxYear。如果是，我们将相应地调整this.minYear和this.maxYear。