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.

The only structures you can use in this assignment are basic arrays and your Stack, Queue, or ArrayList from the previous homeworks.

Do not use built-in data structures like ArrayList.

To accomplish this, add the following constructor to your ArrayList, Stack, or Queue

public ArrayList(Object[] input) {
    data = input;
    numElements = input.length;
}

public Object get(int index) {
return data[index];
}

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

FindFile.java

import java.io.File;
import java.io.FilenameFilter;

/**
*
* @author prmsh
*/
public class FindFile {
String targetFile;
String pathToSearch;
int count;
private String[] filenames;
int maxFiles;
  
public FindFile(int maxFiles) {
this.maxFiles = maxFiles;
this.count=0;
}
//getter setter metthods
public String getTargetFile() {
return targetFile;
}

public void setTargetFile(String targetFile) {
this.targetFile = targetFile;
}

public String getPathToSearch() {
return pathToSearch;
}

public void setPathToSearch(String pathToSearch) {
this.pathToSearch = pathToSearch;
}

public int getCount() {
return count;
}

public void setCount(int count) {
this.count = count;
}

public String[] getFilenames() {
return filenames;
}

public void setFilenames(String[] filenames) {
this.filenames = filenames;
}
  
//file searching method
public void directorySearch(String target, String dirName){
File dir = new File(dirName);
FilenameFilter filter = new FilenameFilter() {
@Override
public boolean accept
(File dir, String name) {//filtering by filename given
return name.startsWith(target);
}
};
this.filenames = dir.list(filter);
this.count = this.filenames.length;
if (this.filenames == null) { //checking for empty direxxtory or invalid directory name
System.out.println("Directory is not found...");
}
else {
for (int i=0; i<this.filenames.length; i++) {
String filename = this.filenames[i];
System.out.println(filename);
}
}
}
}

------------------------------------------------------------------------------------------------------------------------------

Driver.java

public class Driver {
public static void main(String args[]){
//declaring variablaes
String targetFile = "lesson.css";
String pathToSearch ="C:\WCWC:";
//instacnce created
FindFile finder = new FindFile(10);
//calling function
finder.directorySearch(targetFile, pathToSearch);
}
}

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