0

我应该从如下所示的文本文件中获取输入：

rno year rank
22 2004 12
18 2004 17
43 2005 15
43 2006 45
18 2005 23
22 2005 15
43 2004 16
22 2006 20

我应该对这些进行排序并按以下顺序生成输出：

rno  2004  2005  2006
18    17     23        
22    12     15    20    
43    16     15    45

如果卷号没有可用的等级。对于相应的年份，然后打印一个空格

我能够使用以下代码做到这一点：

public class Test {
    public static void main(String args[]) throws FileNotFoundException{
        String[] rollNo=new String[20];
        String[] year=new String[20];
        String[] rank=new String[20];
        int count=1;
        int cnt=0;
        Scanner scn=new Scanner(new File("D:/abc.txt"));
        while(scn.hasNextLine()){
            Scanner sc=new Scanner(scn.nextLine());
                while(sc.hasNext()){
                if(count==1){
                    rollNo[cnt]=sc.next();
                    count++;
                }
                else if(count==2){
                    year[cnt]=sc.next();
                    count++;
                }
                else{
                    rank[cnt]=sc.next();
                    count=count-2;
                }
            }
            cnt++;
        }


            TreeSet<String> yr=new TreeSet<String>();
            for(int i=1;i<year.length;i++)
            if(year[i]!=null)
            yr.add(year[i]);
            TreeSet<String> rl=new TreeSet<String>();
            for(int i=1;i<rollNo.length;i++)
            if(rollNo[i]!=null)
            rl.add(rollNo[i]);
            Hashtable<String,String> y1=new Hashtable<String,String>();
            for(int ct=0;ct<year.length;ct++)
                if(year[ct]!=null)
                    if(year[ct].equals("2004"))
                        y1.put(rollNo[ct], rank[ct]);
            Hashtable<String,String> y2=new Hashtable<String,String>();
            for(int ct=0;ct<year.length;ct++)
                if(year[ct]!=null)
                    if(year[ct].equals("2005"))
                        y2.put(rollNo[ct], rank[ct]);
            Hashtable<String,String> y3=new Hashtable<String,String>();
            for(int ct=0;ct<year.length;ct++)
                if(year[ct]!=null)
                    if(year[ct].equals("2006"))
                        y3.put(rollNo[ct], rank[ct]);

            System.out.print(rollNo[0]);
            for(Object obj:yr)
                System.out.print("  "+obj);
                    System.out.println();
            for(Object obj:rl){
                System.out.print(obj+"   ");
            if(y1.containsKey(obj))
                System.out.print(y1.get(obj)+"    ");
            else
                System.out.print(" ");
            if(y2.containsKey(obj))
                System.out.print(y2.get(obj)+"    ");
            else
                System.out.print("    ");
            if(y3.containsKey(obj))
                System.out.print(y3.get(obj)+"    ");
            else
                System.out.print("    ");

            System.out.println();
            }

    }
}

但是现在的问题是这些年的哈希表是硬编码的，我想让这个程序动态地意味着无论输入（没有年份，排名或滚动没有），我希望我的输出对于任何输入都具有相同的格式。

4

2 回答 2

0

我认为这个任务是关于 3 件事：

  1. 将概念映射到适当的类层次结构
  2. 最重要的是，使用 compareTo 方法和 Collection 的不同 impl
  3. 一些样板文件，例如读取文件/输出

因此，您不应在一个主类中做所有事情，而应该

  • 编写一些映射这些概念的模型类
  • 在这些类中实现 compareTo 方法
  • 根据您的需要使用正确的集合实现（orderedlist？sortedset？）
  • 那么你的 main 方法应该解析文件、实例化对象并让 Java API 完成它的工作！
于 2012-10-06T16:59:53.710 回答
0

我做到了。

import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.util.Iterator;
import java.util.Map;
import java.util.Scanner;
import java.util.Set;
import java.util.StringTokenizer;
import java.util.TreeMap;
import java.util.TreeSet;
public class Nu {

    public static void main(String[] args) throws FileNotFoundException{
        int lineCount=0;
        Scanner scn1=new Scanner(new File("D:/abc.txt"));
        while(scn1.hasNextLine()){
            scn1.nextLine();
            lineCount++;//count no of lines for array length
        }
        int count=1;
        int cnt=0;
        String[] yearss=new String[lineCount];//new array for years
        Scanner scn=new Scanner(new File("D:/abc.txt"));
        while(scn.hasNextLine()){//file yearss array
            Scanner sc=new Scanner(scn.nextLine());
            while(sc.hasNext()){
                if(count==1){
                    sc.next();
                    count++;
                }
                else if(count==2){
                    yearss[cnt]=sc.next();//yearss array is filled
                    count++;
                }
                else{
                    sc.next();
                    count=count-2;
                }
            }
            cnt++;
        }

        TreeSet<String> yr=new TreeSet<String>();//remove duplicate elements from years and sort them
        for(int i=1;i<yearss.length;i++)
            if(yearss[i]!=null)
                yr.add(yearss[i]);//add elements to treeset
        TreeMap allRecord=new TreeMap();//treemap sorts keys
        try{
            File file=new File("D:/abc.txt");//used for file searching
            String[] yearArray=(String[])yr.toArray(new String[0]);//convert treeset to String array
            String roll="";
            String year="";
            String rank="";
            BufferedReader in =new BufferedReader(new FileReader(file));//Filereader reads character by character and bufferedReader reads blocks or streams of data
            String value=in.readLine();//read next line 

            while(value!=null){
                StringTokenizer st=new StringTokenizer(value);//pass line into stringtokenizer
                roll=st.nextToken();//add 1st string to roll
                year=st.nextToken();//add 2nd to year
                rank=st.nextToken();//add third to rank
                TreeMap record=(allRecord.get(roll)!=null)?(TreeMap)allRecord.get(roll):null;//if roll != null then add roll to record else add null
                //returns year and rank//   System.out.println(allRecord.get(roll));
                if(record==null)//if null
                    record=new TreeMap();//if null create new instance
                    else
                    allRecord.remove(roll);//remove null from allrecord
                record.put(year, rank);//put year and rank//every time record is refreshed 
                allRecord.put(roll, record);//put 22 and record//treemap returns null if get(key)==null
                value=in.readLine();//read next line
            }

            Set keyset=allRecord.keySet();//gets all  keys from allRecord
            Iterator i=keyset.iterator();//iterate keyset
            System.out.print("rno"+" ");
            for(int j=0;j<yearArray.length;j++)
                System.out.print(yearArray[j]+"   ");
            //print all years
            System.out.println();
            while(i.hasNext()){
                roll=(String)i.next();//get roll numbers
                if(!roll.equals("rno"))
                System.out.print(roll+"    ");
                else
                    System.out.print("    ");
                Map record=(Map)allRecord.get(roll);//get record using the rollno
                for(int j=0;j<yearArray.length;j++){
                    rank=(String)record.get(yearArray[j]);
                    //get rank for the year
                    if(rank!=null){
                    System.out.print(rank+"    ");
                    }
                    else
                    {
                        System.out.print("       ");
                    }
                }
                System.out.println("");
            }
        }
        catch(Exception e){e.printStackTrace();}
    }
}*
于 2012-10-09T05:06:09.110 回答