java - 双向链表排序: One of the data display twice and the other one is missing

Question

我不知道如何按降序显示具有相同 GPA 的人。如果有两个GPA相同的人，则会显示第一个人两次，第二个GPA相同的人不会显示。

这是主类

  public class N12 { 

public static void main(String[] args) 
{
    N1 myList = new N1();

myList.InsertAt(111,"Broke","Tim","5807404822","CS",3.8,1969,11,12,"New York");
myList.InsertAt(222,"Smith","Tom","5807404822","CS",3.6,1979,3,1,"Dallas");
myList.InsertAt(322,"Cook","John","5807404822","ENG",4.0,1993,4,4,"Boston");   
myList.InsertAt(433,"Keller","Frankin","5807404822","ECON",1.3,1932,6,22,"LA");
myList.InsertAt(213,"Smith","Boris","5807404822","ENG",3.5,1993,5,13,"Austin");

myList.GPADS();
    }
}

这就是方法

public class N1 {
    private class Node
    {  
        Node next;

        int idNum;
        String lname;
        String fname;
        String tel;
        String major;
        double gpa;
        int year;
        int month;
        int date;
        String home;  

        public Node(int id,String ln,String fn,String t,String m,double g,int y, int mon, int d,String h)
        {   idNum=id;
            lname=ln;
            fname=fn;
            tel= t;
            major = m;
            gpa=g;
            year=y;
            month= mon;
            date= d;
            home=h;
            next = null;

        }
        public Node(int id,String ln,String fn,String t,String m,double g,int y, int mon, int d,String h,Node n)
        {   
            idNum=id;
            lname=ln;
            fname= fn;
            tel=t;
            major = m;
            gpa=g;
            year=y;
            month= mon;
            date= d;
            home=h;
            next = n;

        }
    }

    private Node first;
    private Node last;
    private int length;
    private Node currentPos;
    private double gpalist[]=new double [10000];
    private int idd[]=new int [10000];

    private int yearc[]=new int[10000];
    private int monthc[]=new int[10000];
    private int dayc[]=new int[10000];


    public N1()
    {
        length = 0;
        first = last = currentPos = null;
    }


    public void AddToFirst(int id,String ln,String fn,String t,String m,double g,int y, int mon, int d,String h)
    { 
        Node newNode = new Node(id,ln,fn,t,m,g,y,mon,d,h,first);

        first = newNode;
        length++;
        if(length==1) last = newNode;
    }

    public void AddToLast(int id,String ln,String fn,String t,String m,double g,int y, int mon, int d,String h)
    {
        Node newNode = new Node(id,ln,fn,t,m,g,y,mon,d,h);
        if(length==0)
        {
            first=last=newNode;
            length++;
            return;
        }
        last.next = newNode;
        last = newNode;
        length++;
    }


    public void InsertAt(int id,String ln,String fn,String t,String m,double g,int y, int mon, int d,String h)
    {



          gpalist[length]=g;
          idd[length]=id;
           yearc[length]=y;
            monthc[length]=mon;
             dayc[length]=d;
  //System.out.println(length);
        if(id<=0) 
        {
            AddToFirst(id,ln,fn,t,m,g,y,mon,d,h);
            return;
        }
        if(id>=length)
        {
            AddToLast(id,ln,fn,t,m,g,y,mon,d,h);
            return;
        }
        Node newNode = new Node(id,ln,fn,t,m,g,y,mon,d,h);
        Node current = first;
        for(int i=0;i<id-1;i++) current = current.next;
        newNode.next = current.next;
        current.next = newNode;
        length++;



    }




    public  void GPADS()
    { 
            String output="";

        int i;
                int j;
                double value;
        for(i=1;i<gpalist.length;i++)
        {
            value = gpalist[i];
            j = i-1;
            while(j>=0&&gpalist[j]<value) 
            {
                gpalist[j+1] = gpalist[j];
                j--;
            }
            gpalist[j+1] = value;
        }

  System.out.println("This is Descending by Gpa: ");
                  for(i=0;i<gpalist.length;i++)
        {
                    if(gpalist[i]!=0)
                    {
                   ByGPA(gpalist[i]); 

                    }

    }
        }


    public String ByGPA(double gpa)//second method
{      String output="";
        Node current = first;

while(current!=null)
       {

    if(current.gpa==gpa)
    {

            output = output+" "+current.idNum+" "+current.lname+" "+current.fname+" "+current.tel
                    +" "+current.major+" "+current.gpa+" "+current.year+" "+current.month
                            +" "+current.date+" "+current.home;  
          System.out.println(output);
         return null;
        }
    current = current.next;

    }
              return "";
}



}

输出(不同 GPA):

这是按 GPA 降序排列:

• 322 Cook John 5807404822 ENG 4.0 1993 4 4 Boston
• 111 Broke Tim 5807404822 CS 3.8 1969 11 12 New York
• 222 Smith Tom 5807404822 CS 3.6 1979 3 1 Dallas
• 213 Smith Boris 5807404822 ENG 3.5 1993 5 13 Austin
• 433 Keller Frankin 5807404822 ECON 1.3 1932 6 22 LA

如果我把Boris GPA改成3.8，就不会显示，而Broke会显示两次。

输出(具有相同的 GPA):这是按 GPA 降序排列:

• 322 Cook John 5807404822 ENG 4.0 1993 4 4
• Boston 111 Broke Tim 5807404822 CS 3.8 1969 11 12 New York
• 111 Broke Tim 5807404822 CS 3.8 1969 11 12 New York
• 222 Smith Tom 5807404822 CS 3.6 1979 3 1 Dallas
• 433 Keller Frankin 5807404822 ECON 1.3 1932 6 22 LA

Answer 1

您的代码有很多不必要的复杂性，我也无法捕获代码，因为它具有非常不可读的变量名称等。我强烈建议您尽可能地使其可读。

我认为您问题的答案在 ByGPA 方法中。

当它找到第一个 gpa 时，它会打印它，但由于 return 语句，它无法迭代到其他元素。 您可以删除此返回语句或重新考虑 ByGPA 方法的实现。