Scanner and .hasNext () problem

Question

I am new to Java and very new to the class Scanner. I am writing a program that asks the user for a word, and then this word is distorted inside the file. Each time a word is found, it is printed on a new line in JOptionPane, as well as in the word before and after it. Everything functions as it should, with two exceptions:

• If the searched word is the last word in the file, then a "NoSuchElementException" is thrown.

• If the search word appears twice in a row (unlikely, but still a problem that I discovered), it returns it only once. For example, if the search word was "is" and "He said he had enough. He was all night," were sentences in a file, then the output:

  he had had
  He had been
  

  whereas it should be:

  he had had
  had had enough.
  He had been
  

I believe that my problem is what I use while(scan.hasNext()), and in this cycle I use scan.next()twice. I can’t find a solution for this, though, while retaining what I would like to return to the program.

Here is my code:

//WordSearch.java
/*
 * Program which asks the user to enter a filename followed
 * by a word to search for within the file. The program then
 * returns every occurrence of this word as well as the
 * previous and next word it appear with. Each of these
 * occurrences are printed on a new line when displayed
 * to the user.
 */

import java.io.FileNotFoundException;
import java.io.FileReader;
import java.util.ArrayList;
import java.util.Scanner;
import javax.swing.JOptionPane;

public class WordSearch {

    public static void main(String[] args) throws FileNotFoundException {

        String fileName = JOptionPane.showInputDialog("Enter the name of the file to be searched:");
        FileReader reader = new FileReader(fileName);

        String searchWord = JOptionPane.showInputDialog("Enter the word to be searched for in \"" + fileName + "\":");
        Scanner scan = new Scanner(reader);

        int occurrenceNum = 0;
        ArrayList<String> occurrenceList = new ArrayList<String>();
        String word = "", previousWord, nextWord = "", message = "", occurrence, allOccurrences = "";

        while(scan.hasNext()){
            previousWord = word;
            word = scan.next();

            if(word.equalsIgnoreCase(searchWord)){
                nextWord = scan.next();

                if(previousWord.equals("")){
                    message = word + " is the first word of the file.\nHere are the occurrences of it:\n\n";
                    occurrence = word + " " + nextWord;
                }
                else{
                    occurrence = previousWord + " " + word + " " + nextWord;
                }

                occurrenceNum++;
                occurrenceList.add(occurrence);
            }
        }

        for(int i = 0; i < occurrenceNum; i++){
            allOccurrences += occurrenceList.get(i) + "\n";
        }

        JOptionPane.showMessageDialog(null, message + allOccurrences);

        scan.close();
    }
}

Also, on the side of the note: how can I implement to scan.useDelimeter()ignore any, question marks, commas, periods, apostrophes, etc.?

Answer 1

If the search word is the last word in the file, it is thrown NoSuchElementException.

This is because of this line:

if(word.equalsIgnoreCase(searchWord)) {
    nextWord = scan.next();
    ...
}

You do not check whether it is scan hasNext(), right for scan.next(). You can fix this by adding a condition with a callscan.hasNext()

(, , ), .

: , .

: , , previousWord ( ) while.

Answer 2

, hasNext, .

while(scan.hasNext()){
    previousWord = word;
    word = scan.next();

    if(word.equalsIgnoreCase(searchWord) && scan.hasNext()){ // this line change
        nextWord = scan.next();

        if(previousWord.equals("")){
            message = word + " is the first word of the file.\nHere are the occurrences of it:\n\n";
            occurrence = word + " " + nextWord;
        }
        else {
            occurrence = previousWord + " " + word + " " + nextWord;
        }

        occurrenceNum++;
        occurrenceList.add(occurrence);
    }
}

equals ignore. .equals().

Answer 3

, , previousWord. - :

while (scan.hasNext()) {
    previousWord = word;
    word = nextWord;
    nextWord = scan.next();

word. , , previousWord nextWord. , , .

hasNext() next() .

, nextWord . , , .