Question

I’m trying to create a program that reads in a .txt file with multiple lines containing lists of names. A sample of the test file is below:

Joe Sue Meg Ry Luke

Kay Trey Phil George

I have three classes(also below). Everything works fine, but I would like to know which friend-set has the greatest number of friends (i.e. in the test file Joe would have the greatest number of friends)

The data isn’t limited to only two friend-sets though…

import java.io.*; 

//Finds the file
public class ReadFileLine {     
public static void main(String[] args) throws Exception {       
    BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in),1);
    System.out.println("Hello! " + "Please enter the name of your test file: " +
    "\n**Hint** for this assignment the file name is: friendsFile.txt\n");
    String fileName= keyboard.readLine();
    System.out.println(fileName);//
    FileLine doLine = new FileLine();
    doLine.readList(fileName);

}
}

Class 2:

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;


public class InStringFile {

//read the file
private BufferedReader in;
//read each line
private String nextLine;


//handle exceptions 
public InStringFile(String filename) {   

    //line by line input
    try {       
    in = new BufferedReader(new FileReader(filename));
      nextLine = in.readLine();
    }
    catch (FileNotFoundException ee){
       System.out.println("We're sorry,\n" +"File " + filename + " cannnot be found.");
       System.exit(0);
    }
    catch (IOException e){
       System.out.println("We're sorry,\n" +"File " + filename + " cannot be read.");
       System.exit(0);
  }
}

//reads the file as string
public String read() {
  String current = nextLine;
  try {
   nextLine = in.readLine();
  }

  //catch exception
  catch (IOException e){
     System.out.println("We're sorry, this file cannot be read.");
     System.exit(0);
  }
  return current;
}


public boolean endOfFile() {
    return (nextLine == null);
}

//close the file
public void close(){
   try {
      in.close();
      in = null;
   }

   //catch if file cannot be closed
   catch (IOException e){
       System.out.println("Problem closing file.");
       System.exit(0);
   }
}
}

Class 3:

import java.util.StringTokenizer;


public class FileLine {


     public  void readList (String fileName) throws Exception {       

        //opens the file and controls file reading               
        InStringFile reader = new InStringFile(fileName);
        System.out.println("\nFile Found!" + 
        " Now reading from file: " + fileName + "\n");

        // line by line read              
        String line;

        do  {
          line = (reader.read());

          //print the friend list
          System.out.println("The following friend-set exists: " + line);  
          this.TokenizeString(line);

        }while (!reader.endOfFile()); 

        reader.close(); 
    }

     //number of friends
    public void TokenizeString(String nameList){
        StringTokenizer tokens = new StringTokenizer(nameList);
        System.out.println("The number of friends in this friend-set is: " + tokens.countTokens()); 

    }

}

Okay, so I modified the fileLine class to be the following:

import java.util.StringTokenizer;


public class FileLine {


     public  void readList (String fileName) throws Exception {       

        //opens the file and controls file reading               
        InStringFile reader = new InStringFile(fileName);
        System.out.println("\nFile Found!" + 
        " Now reading from file: " + fileName + "\n");

        // line by line read              
        String line;

        do  {
          line = (reader.read());

          //print the friend list
          System.out.println("The following friend-set exists: " + line);  
          this.TokenizeString(line, line);

        }while (!reader.endOfFile()); 

        reader.close(); 
    }

     //number of friends
    public void TokenizeString(String nameList, String nameByName)  {
        StringTokenizer tokens = new StringTokenizer(nameList);
        System.out.println("The number of friends in this friend-set is: " + tokens.countTokens()); 

        StringTokenizer st = new StringTokenizer(nameByName, " ");
        String firstName = st.nextToken();
        System.out.println("Friend-set Leader: " + firstName);

        }

    }

So now the code returns the first name in each line… I still am stuck on how to store the number of tokens. IF I could do that then I could compare and return the greatest number (right?)…

Answer 1

Let tokenizeString(..) return the number of friends. Then:

int maxFriends = 0;
int maxFriendsLine = 0;
int currentLine = 0;
while (..) {
    int friends = tokenizeString(..);
    if (friends > maxFriends) {
        maxFriendsLine = currentLine;
        maxFriends = friends;
    }
    currentLine++;
}

A few notes:

• see if you can use commons-lang FileUtils.readLines(..) or guava Files.readLines(..)
• prefer str.split(" ") instead of StringTokenizer
• use lower-case methods – that’s what the java convention prescribes.