Recursively process folders

Folders and Files in Java

• A File object can refer to a Folder or an actual file.
• How to create a file object:
  File myDir = new File("C:/users/joe/myWork");
  • Note: The prior line does not actually create a file. Rather, all that you did in this line is create an object that represents a path to a folder that may or may not exist on your computer! Just because you decided to create a File object named myDir does not mean that this folder actually exists. Consider this analogy : It's the same as writing a newspaper article about a man named "Mr. Morris" (that's my name). Just becuase you wrote an article in a newspaper that "Mr. Morris went to the foodstore" does not mean that there is actually a real Mr. Morris or that he went to the foodstore. It's just data on a page (in this case a newspaper) that may or may not relate to the real world.

• System.getProperty("user.home")
  • This stores the folder of the current user such as

    C:\Users\joe smith

File myDir = new File("C:\users\jane smith\documents\myWork\);
File myFile = new File("C:\users\jane smith\documents\abc.doc");

• Constructor takes a String paramater
• File myFile = new File("C:\Users\joe smith");
• String getName()

  Method Call	Return
  myDir.getName()	myWork
  myFile.getName();	abc.doc

  • String getPath()

  Method Call	Return
  myFile.getPath()	C:\users\jane smith\documents\abc.doc
  myDir.getPath();	C:\users\jane smith\documents\myWork

• boolean exists() Returns true if the folder or file actually exists on the computer

Useful methods for Directories and for this project in particular

• listFiles()
  • returns an array of abstract path names (paths) denoting the directories and files inside a particular directory. Returns null if method is called by a file (see first example below myFile.listFiles() ).

  Method Call	Return
  myFile.listFiles()	null
  myDir.listFiles();	an array of abstract path names representing whatever files and folders are within myDir.

• boolean isFile() self descriptive
• boolean isDirectory() self-descriptive
• boolean isHidden()
• boolean canRead() : returns true if you are permitted to read the file referred to by the file object and false otherwise.

Some of the methods up above are demonstrated in the following classFileDemo.java

import java.io.*;
public class FileDemo {

public static void main(String[] args){
	File myDir = new File("C:/users/jane smith/documents/myWork/");
	File myFile = new File("C:/users/jane smith/documents/abc.doc");

	System.out.println(myDir.getName());
	System.out.println(myFile.getName());
	System.out.println(myDir.getPath());
	System.out.println(myFile.getPath());
	}
}

• Task #1) Find or create a folder in your H drive that has several files and folders in it.
• Task #2) Write a class that
  • 1) Creates a file object that refers to the folder in task #1
  • 2) Prints out a list of all the files and folders within this folder

The Project

Files for this project: 1) FileIndexer.java 2) FolderIndexer.java

Since you'll probably want to convert an array to an ArrayList(listFiles() returns an array), here's some code to get you going.

import java.io.File;
import java.util.Arrays;
import java.util.List;


public class fileArrayList {

	public fileArrayList(){
		File[] filesInHomeDir = new File(System.getProperty("user.home")).listFiles();
		List<File> wordList = Arrays.asList(filesInHomeDir);

		for(File f: filesInHomeDir)
			System.out.println(f);
	}
	
	
	public static void main(String[] args){
	 fileArrayList p = new fileArrayList();
	
	}
	
}