filterTextFile.java

import java.io.*;
import java.util.*;

public class FilterTextFile {
    public static void main(String[] args) throws FileNotFoundException {
        Scanner fScan, cScan = new Scanner(System.in);
        String inFile, outFile, findStr;
        FileInputStream fileInput;
        PrintWriter fileOutput;
        
        // Get input file.
        System.out.print("Input file ? ");
        inFile = cScan.nextLine();
        fileInput = new FileInputStream(inFile);
        fScan = new Scanner(fileInput);
        
        // Get output file.
        System.out.print("Output file ? ");
        outFile = cScan.nextLine();
        fileOutput = new PrintWriter(outFile);
        
        // Get search string.
        System.out.print("String to search for ? ");
        findStr = cScan.nextLine();
        
        // Filter input file to output file.
        while (fScan.hasNextLine()) {
            String line = fScan.nextLine();
            if (line.contains(findStr)) {
                fileOutput.println(line);
            }
        }
        fileOutput.close();
    }
}