Lab 5: Recursive Grep

In this lab, you will create a version of the grep command-line utility that supports recursively searching for files matching a target string.

Instructions

We encourage you to work with a partner. If you worked with a partner on the Simple Grep lab, work with the same partner on this assignment. You can reuse some of your code from the Simple Grep lab in this assignment.

Start by downloading recursive-grep.zip, which contains the starter files for this assignment.

Explore the poems subdirectory. Notice that the text files containing the poems are stored in subdirectories by author and download source.

Your task is to create a RecursiveGrep class which supports recursively searching within a directory to find files which match a target string. When your program finds a line matching the target string, it should print the name of the file along with the matching line.

For example, searching through poems directory for the string dream:

> java-introcs RecursiveGrep dream poems
poems/project-gutenberg/alexander-pushkin/the-roussalka.txt The dreamy wave she vanished under.
poems/public-domain-poetry/charlotte-bronte/life.txt Life, believe, is not a dream
poems/public-domain-poetry/charlotte-bronte/the-wood.txt We'll seek a couch of dreamless ease;
poems/public-domain-poetry/edgar-allan-poe/the-raven.txt Doubting, dreaming dreams no mortals ever dared to dream before;
poems/public-domain-poetry/edgar-allan-poe/the-raven.txt And his eyes have all the seeming of a demon's that is dreaming,

You should implement the searchFile() and findFiles() methods:

/**
 * Print lines within the file that match the target string.
 *
 * @param target the string we are searching for
 * @param file   the text file we are searching within
 */
public static void searchFile(String target, File file)

/**
 * Find and search within files for lines matching the target string.
 *
 * @param target    the string we are searching for
 * @param directory the directory we are searching within
 */
public static void findFiles(String target, File directory)

Your main method should contain:

public static void main(String[] args) {
    findFiles(args[0], new File(args[1]));
}

Before you start coding, decide:

  1. Which operations will form your recursive step (i.e., they need to be performed recursively)?
  2. Which operations will form your base case (i.e., they don’t need to be performed recursively)?

Hint: To read from a file, you can use the textbook’s In class. To find files you will need to use the Java Standard Library’s File class. In particular, read the documentation for the methods listFiles(), isDirectory(), and isFile().

Hint: If IntelliJ doesn’t add it automatically, you may need to add this import statement to the top of your RecursiveGrep.java file to use the File class:

import java.io.File;

Submit

Upload the following files to Gradescope:

Finally, be sure to indicate your group member on Gradescope.

Learning Goals