Introduction & Driver In this assignment, your job is to write a class that sear

Question

Introduction & Driver

In this assignment, your job is to write a class that searches through a file hierarchy (a tree) for a specified file. Your FindFile class will search a directory (and all subdirectories) for a target file name.

For example, in the file hierarchy pictured above, the file “lesson.css” will be found once in a directory near the root or top-level drive name (e.g. “C:”) . Your FindFile class will start at the path indicated and will search each directory and subdirectory looking for a file match. Consider the following code that could help you build your Driver.java:

String targetFile = “lesson.css”;

String pathToSearch =”C:\WCWC”;

FindFile finder = new FindFile(MAX_NUMBER_OF_FILES_TO_FIND);

Finder.directorySearch(targetFile, pathToSearch);

File Searching

In general, searching can take multiple forms depending on the structure and order of the set to search. If we can make promises about the data (this data is sorted, or deltas vary by no more than 10, etc.), then we can leverage those constraints to perform a more efficient search. Files in a file system are exposed to clients of the operating system and can be organized by filename, file creation date, size, and a number of other properties. We’ll just be interested in the file names here, and we’ll want perform a brute force (i.e., sequential) search of these files looking for a specific file. The way in which we’ll get file information from the operating system will involve no ordering; as a result, a linear search is the best we can do. We’d like to search for a target file given a specified path and return the location of the file, if found. You should sketch out this logic linearly before attempting to tackle it recursively.

FindFile Class Interface:

FindFile(int maxFiles)

This constructor accepts the maximum number of files to find.

void directorySearch(String target, String dirName)

The parameters are the target file name to look for and the directory to start in.

int getCount()

This accessor returns the number of matching files found

String[] getFiles()

This getter returns the array of file locations, up to maxFiles in size.

Requirements

Your program should be recursive.

You should build and submit at least two files: FindFile.java,Driver.java,

Throw an exception (IllegalArgumentException) if the path passed in as the starting directory is not a valid directory.

Throw an exception if you’ve found the MAX_NUMBER_OF_FILES_TO_FIND, and catch and handle this in your main driver.

You’re program shouldn’t crash, but rather exit gracefully in the unusual situation that we’ve discovered the maximum number of files we were interested in, reporting each of the paths where the target files were found.   

Notes and Hints

Consider looking into the File class in Java for helpful methods like isDirectory() and toString().

http://docs.oracle.com/javase/7/docs/api/java/io/File.html

Useful File details have been taken from the link above and copied here for referenceimport java.io.File;            

Import the File class to use it.

File f = new File(dirName);

Next, create a File object.

String[] fileList = f.list()

This list files in current directory as Strings

File aFile = new File(dirName + "\" + fileList[i]);

Notice the concatenation in the new File object

if (aFile.isDirectory()) {

check whether it is a directory

Test your FindFile.java class.

Try to find a file that exists once

Try to find a file that doesn’t exist

Try to find a file that exists twice

Try to find a file that exists MAX_NUMBER_OF_FILES_TO_FIND

…

In your recursive call, make sure you don’t loose the directory path by concatenating it with the file name.

Explanation / Answer

Answer:

/**JAVA PROGRAM TO SEARCH FOR A FILE IN THE DIRECTORY****/

import java.io.*;

import java.util.*;

import java.lang.*;

//CLASS FindFile

class FindFile

{

int maxFiles;

int filesCount;

//STRING ARRAY TO HOLD THE MATCHED LOCATIONS

String[] matchFiles;

public FindFile(int maxFiles)

{

this.maxFiles=maxFiles;

filesCount=0;

matchFiles=new String[maxFiles];

}

public void directorySearch(String target,String dirName)throws IllegalArgumentException

{

//CREATE FILE OBJECT FOR THE DIRECTORY

File f=new File(dirName);

//This list files in current directory as Strings

String[] fileList=f.list();

for(int i=0;i<fileList.length;i++)

{

File aFile=new File(dirName+"\"+fileList[i]);

// check whether it is a directory

if(aFile.isDirectory())

{

//RECURSIVE CALL TO SEARCH THROUGH THIS DIRECTORY

directorySearch(target,aFile.getName());

}

//ELSE IF FILENAME IS MATCHED WITH TARGET FILENAME THEN STORE //THE FILE LOCATIONS AND INCRMENT THE FILES COUNT BY 1

else if(target.equalsIgnoreCase(aFile.getName()))

{

matchFiles[filesCount]=aFile.getParentFile().getName();

filesCount++;

}

}

}

//RETURN THE MATCHED FILES COUNT

public int getCount()

{

return filesCount;

}

//RETURN STRING ARRAY OF MATCHED FILE LOCATIONS

public String[] getFiles()

{

return matchFiles;

}

}

//Driver.java

public class Driver

{

//MAIN METHOD

public static void main(String[] args)

{

String targetFile="lesson.css";

String pathToSearch="C:\WCWC";

FindFile Finder=new FindFile(10);

//CALL directorySearch TO SEARCH THE TARGET FILE IN //THE GIVEN PATH

Finder.directorySearch(targetFile,pathToSearch);

//PRINT THE NUMBER OF MATCHED FILES

System.out.println("The NUMBER OF MATCHED FILES:"+Finder.getCount());

//print the FILE LOCATIONS

System.out.println("The file Locations:"+Arrays.toString(Finder.getFiles()));

}

}

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.