Question

search the file "myfile.txt" for any occurrences of "Some target string" and print the lines where the string is found.

In this assignment, write your own java version of this program:

1. Name the program LastnameFirstname1 (this is not really an appropriate name for such a program, but following this convention greatly eases the grading process). Example: WhiteMax1
2. Allow the user to specify the string they are searching for and the file they wish to search with command line arguments. To replicate the above findstr and grep examples, the program would be executed with the following command: java WhiteMax1 "Some target string" myfile.txt  (for help using command line arguments, see this article).
3. Search each line of the file for the target string. For every occurrence found, first print out the line number where it has been found, the index of the target string's start position in that line, and the entire line itself. For example, searching line 5, "My dog is a good boy" for the target string "dog" would print: 5:3 My dog is a good boy   (If no occurrences are found, nothing needs to be printed. If multiple occurrences are found in the same line, print the line multiple times with each index position. File line numbers start at 1, not 0)

To complete this assignment you will need to use Scanner, File, and String. Consider reviewing the documentation for these classes. The attached file is provided as an example text file for developing and testing your program.

Answer 1

If you have any doubts, please give me comment...

import java.io.*;

import java.util.Scanner;

public class WhiteMax1{

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

        if(args.length!=2){

            System.out.println("Usage: java WhiteMax1.java <Some target String> filename");

            System.exit(0);

        }

        Scanner fileScnr = new Scanner(new File(args[1]));

        String line;

        String searchWord = args[0];

        int line_no = 1, pos;

        while(fileScnr.hasNextLine()){

            line = fileScnr.nextLine();

            pos = line.indexOf(searchWord);

            while(pos!=-1){

                System.out.println(line_no+":"+pos+" "+line);

                pos = line.indexOf(searchWord, pos+1);

            }

            line_no++;

        }

        fileScnr.close();

    }

}