Thread: Output some data from a txt file?

I have an assignment at school in which i have to make a program that reads a "Product number" and outputs the "Product Name". Those two pieces of info is located in a txt file, separated by a "," like this:

10002,iron
10003,gold
10003,cobber

Right now I'm able to read the txt file and store it in an array and output the entire array. This is my 2 classes:

FileData (main)

package textfiles;
import java.io.IOException;
 
public class FileData {
 
 
	public static void main(String[] args) throws IOException {
 
		String file_name = "/Users/jack_sogaard/Desktop/store.txt";
 
		try {
			ReadFile file = new ReadFile(file_name);
			String[] aryLines = file.OpenFile();
 
			int i;
			for ( i=0; i < aryLines.length; i++ ) {
			System.out.println( aryLines[ i ] ) ;
			}
		}
		catch (IOException e) {
			System.out.println(e.getMessage() );
		}
	}
}

And ReadFile

package textfiles;
import java.io.IOException;
import java.io.FileReader;
import java.io.BufferedReader;
 
public class ReadFile {
	private String path;
 
	public ReadFile(String file_path) {
		path = file_path;
	}
 
	public String[] OpenFile() throws IOException {
 
		FileReader fr = new FileReader(path);
		BufferedReader textReader = new BufferedReader(fr);
 
		int numberOfLines = readLines();
		String[] textData = new String[numberOfLines];
		int i;
 
		for (i=0; i < numberOfLines; i++) {
			textData[i] = textReader.readLine();
		}
		textReader.close();
		return textData;
	}
 
	int readLines() throws IOException {
 
		FileReader file_to_read = new FileReader(path);
		BufferedReader br = new BufferedReader(file_to_read);
 
		String aLine;
		int numberOfLines =0;
 
		while (( aLine = br.readLine()) !=null) {
				numberOfLines++;
		}
		br.close();
		return numberOfLines;
	}	
}

Any help would be appreciated

/jaze

what is a Map?
My specific question is: how should i do this? can i create a list of 2 arrays, one containing numbers, and the other containing names and then the the index of the product number (etc. [1]) is corresponding to the index of the product name?

Okay, i've been trying some different things now and gone through a lot of different tutorials on this subject, and yes, mapping is the method i will use.

I've written a class that reads the txt file puts it into columns and then out prints the map. Then a user is able to input the product number, and the class should print out the product name, but it only prints out "null" - where did i go wrong?

Here is my class:

import java.io.*;
import java.util.*;
 
 
class Test {
    public static void main(String[] args) throws FileNotFoundException {
        Scanner scanner = new Scanner(new FileReader("store.txt"));
 
        //Create HashMap
        HashMap map = new HashMap();
 
        while (scanner.hasNextLine()) {
            String[] columns = scanner.nextLine().split(",");
            map.put(columns[0], columns[1]);
        }
 
        //Prints the map, just to check if its ok
        System.out.println(map);
 
        //Takes input from user (Product Number)
        System.out.println("input product number");
        Scanner prodNoScan = new Scanner(System.in);
        String prodNo = prodNoScan.nextLine();
 
        //Get the value from the key "prodNo" and print put product name
        Object productName = map.get("prodNo");
        System.out.println("The product is:" +productName);
 
    }
}

Hello j4ze!
I think the problem lies in this line

Object productName = map.get("prodNo");

With the above statement you are searching for a key named prodNo which doesn't exist. You actually want to search for prodNo which is entered by the user (ie 10001, etc.). Can you see the difference between

map.get("prodNo");

and

map.get(prodNo);

Thank you, that helped a lot. Yeah it makes a whole lot of sense to leave out the " ".
Once again, thank you.