Sequential ID Replacer

package txtIDReplacer;

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class TxtIDReplacer {

    // Global variables
    public static String path = "E:\\User\\Downloads\\";

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

        // Read the list of replacement values for all IDs
        // Create array
        List<String> names = new ArrayList<String>();

        //Start the scanner
        File f = new File(path + "items.txt");
        Scanner s = new Scanner(f);

        //Go through the lines and save them into the array
        while(s.hasNext()) {
            String line = s.nextLine();
            names.add(line);
        }
        s.close();
        String[] values = names.toArray(new String[0]);

        // Read the main file which contains the IDs
        // Create string
        String mainFile = "";

        //Start the scanner
        File f2 = new File(path + "for_replace.txt");
        Scanner s2 = new Scanner(f2);

        //Go through the lines and add them to the string
        while(s2.hasNext()) {
            String line = s2.nextLine();
            mainFile = mainFile + "\n" + line;
        }
        s2.close();


        // Replace all ocurrences of the regex pattern in the main file with the elements of the array
        // It is important to match the IDs in descending order to avoid single-digit IDs replacing everything
        for(int i = values.length - 1; i >= 0; i--) {
            mainFile = mainFile.replaceAll("" + i, values[i]);
        }

        // Save to file in output folder
        // Initiate the FileWriter with the designated file path
        FileWriter f3 = new FileWriter(path + "replaced.txt");
        BufferedWriter bW = new BufferedWriter(f3);
        bW.write(mainFile);
        bW.close();

        System.out.println("Done!");

    }

}