Question

The program that I am trying to create is a program that takes words from a user defined file, saves those words as variables and then searches a different user defined file for those words, outputting there location.

The program works up to and including the point where the program takes the words and saves them as variables. The problem with the program is that the search method returns a null result. My main suspicions are that the code in the search method is incompatible with the code in the read method, or that the 2 methods aren’t running simultaneously.

The search method is in the searching class and the read method is in the reading class.

Here is my code (Containing all 3 of my classes), please excuse all of the imports.

This is the first class:

import java.io.FileNotFoundException;
import java.util.Scanner;

public class Combination{

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

    Scanner userInput = new Scanner(System.in);
    Reading ReadingObject = new Reading();        
    System.out.println("Please enter the file that you wish to open");
    String temp = userInput.nextLine();
    ReadingObject.setFileName(temp);
    ReadingObject.read();
    Scanner searchForWord = new Scanner(System.in);
    Searching SearchingObject = new Searching();
    System.out.println("Please enter the file that you would like to search for these words in");
    String temp1 = searchForWord.nextLine();
    SearchingObject.setFileName(temp1);
    SearchingObject.search();

}    
}

This is the second class:

import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.FileInputStream;
import java.io.InputStreamReader;

class Reading {
private String file;
public void setFileName(String fileName){
    file = fileName;
}
public String getFileName(){
    return file;
}
public void read(){
    try{
        //Choosing the file to open
        FileInputStream fstream = new FileInputStream(getFileName());

        //Get the object of datainputstream
        DataInputStream in = new DataInputStream(fstream);
        BufferedReader br = new BufferedReader(new InputStreamReader(in));
        String strLine = null;

        //Read the file line by line
        while((strLine = br.readLine()) != null){
            //      \\s+ means any number of whitespaces between tokens
            String [] tokens = strLine.split("\\s+");
            String [] words = tokens;
            for(String word : words){
                System.out.print(word);
                System.out.print(" ");

                Searching SearchingObject = new Searching();
                SearchingObject.setWord(word);
            }
            System.out.print("\n");   
        }
        in.close();  
    }
    catch(Exception e){
        System.err.println("Error: " + e.getMessage());  
    }
}
}

This is the third class:

import java.io.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

class Searching {
private String file1;
public void setFileName(String fileName){
    file1 = fileName;
}
public String getFileName(){
    return file1;
}
private String word1;
public void setWord(String wordName){
    word1 = wordName;    
}
public String getWord(){
    return word1;
}

public void search() throws FileNotFoundException{

    try{
        //Choosing the file to open
        FileInputStream fstream = new FileInputStream(getFileName());

        //Get the object of datainputstream
        DataInputStream in = new DataInputStream(fstream);
        BufferedReader br = new BufferedReader(new InputStreamReader(in));
        String strLine = null;

        while((strLine = br.readLine()) != null){

            Pattern p = Pattern.compile(getWord());
            Matcher m = p.matcher(strLine);

        int start = 0;
        while (m.find(start)) {
            System.out.printf("Word found: %s at index %d to %d.%n", m.group(), m.start(), m.end());
            start = m.end();
                }
          }        
    }
    catch(Exception e){
        System.err.println("Error: " + e.getMessage());
    } 
}
}

Any help will be greatly appreciated.

Regards

Answer 1

Your code is hard to read. Your reading class does not only read; it also searches. You should call it something that reflects its intended use. However, it forgets to tell its searching object where to search, and does not pass the reference to this object to anyone else. In this snippet

for (String word : words) {
    System.out.print(word);
    System.out.print(" ");

    searching searchingObject = new searching();
    searchingObject.setWord(word);
}

you are essentially not doing anything. The reference to searchingObject is lost forever.

Your reading class should keep an ArrayList of words to be searched for in the searching, instead of instancing searching objects.

Your searching class should take, as a constructor parameter, one of these ArrayLists — and convert it into a single regex, which is much more efficient than reading the file once per word to search for. You can search for “a”, “b” and “c” using the single regular expression “a|b|c”. Works with longer words, too. Escape them first to avoid problems.

Oh, and please, please follow naming guidelines. Call your reading a TokenReader, and your searching a WordListSearcher…