Question

complete this in java

import java.io.File;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.Random;
import java.util.Scanner;

public class WordDetective {

/**
* Finds the specified set of words in the specified file and returns them
* as an ArrayList. This finds the specified set in the file which is on the
* line number of the set. The first line and set in the file is 1.
*
* This returns an ArrayList with the keyword first, then : and then followed
* by the rest of the words in the set, space delimited.
* Note: The String class indexOf method can be used to find the :. The keyword is
* everything prior to the : and the keywords are space delimited after.
*
* An error message to System.out should be printed and an empty list returned
* in the following cases:
* A set number is not found.
* "Error: set " + fileSetNumber + " not found."
* A set doesn't have the : after the keyword.
* "Error: colon (:) not found in set " + fileSetNumber + "."
*
* Example file format:
* about: about auto bat boat but out tab tub
* other: her hero hot other the toe
* their: her hire hit the their tie tier tire
*
* If the set number is 2 the returned ArrayList should contain:
* [other, her, hero, hot, other, the, toe]
*
* @param filename The file containing word sets.
* @param set The number of the set, starting with 1.
* @return The set of words, with the keyword first and later in the list.
* @throws FileNotFoundException
*/
public static ArrayList<String> loadWordSet(String filename, int set) throws FileNotFoundException {
return null; //TODO
}
  

Answer 1

If you have any problem with the code feel free to comment.

Program

import java.io.File;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.NoSuchElementException;
import java.util.Scanner;

public class Test {
   public static void main(String[] args) throws FileNotFoundException {
       Scanner sc = new Scanner(System.in);
      
       System.out.print("Enter filename: ");
       String filename = sc.nextLine();
       System.out.print("Enter set number: ");
       int set = sc.nextInt();
       sc.close();
      
       ArrayList<String> list = loadWordSet(filename, set);
      
       if(list != null) {
           System.out.println("The list of words : "+list);
       }
   }

   public static ArrayList<String> loadWordSet(String filename, int set) throws FileNotFoundException {
       Scanner sc = new Scanner(new File(filename));
       ArrayList<String> list = new ArrayList<>();
       String str = "";
       boolean check = true;

       // checking if the line number exists or not
       for (int i = 1; i <= set; i++) {
           check = sc.hasNext();

           // handling exception if no line found
           try {
               str = sc.nextLine();
           } catch (NoSuchElementException e) {
           }
       }

       sc.close();

       if (!check) {
           System.out.println("Error: set " + set + " not found");
           return null;
       }

       // checking colon
       String[] ar = str.split(" ");
       if (ar[0].indexOf(':') == -1) {
           System.out.println("Error: colon (:) not found in set " + set + ".");
           return null;
       }

       // removing colon
       ar[0] = ar[0].replaceFirst(":", "");

       // adding words to list
       for (String i : ar) {
           list.add(i);
       }
       return list;
   }
}

Output