我应该从文本文件中获取输入，如下所示：
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
我应该对它们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
如果没有可用的滚动排名。相应的年份然后打印一个空格
我能够使用以下代码执行此操作：
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什么（没有年份，排名或滚动否），我希望我的输出以相同的格式输入任何输入
答案 0 :(得分：0)
我认为这项任务大约有三件事：
因此，不应该在一个Main类中执行所有操作，而应该
答案 1 :(得分：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();}
}
}*