oop_Directory.java

package oop;

import java.util.ArrayList;

/**
 * @author Bazlur Rahman Rokon
 * @since 3/31/17.
 */
public class Directory extends Entry {
	protected ArrayList<Entry> contents;

	public Directory(Directory parent, String name) {
		super(parent, name);
		this.contents = new ArrayList<>();
	}

	@Override
	public int size() {

		return contents.stream()
			.mapToInt(Entry::size)
			.sum();
	}

	public int numberOfFiles() {
		int count = 0;
		for (Entry content : contents) {
			if (content instanceof Directory) {
				count++;/// Directory counts as a file
				Directory directory = (Directory) content;
				count += directory.numberOfFiles();
			} else if (content instanceof File) {
				count++;
			}
		}

		return count;
	}

	public void addEntry(Entry entry) {
		contents.add(entry);
	}

	protected boolean deleteEntry(Entry entry) {
		return contents.remove(entry);
	}

	public ArrayList<Entry> getContents() {
		return contents;
	}
}

oop_Entry.java

package oop;

import java.time.LocalDateTime;

/**
 * @author Bazlur Rahman Rokon
 * @since 3/31/17.
 */
public abstract class Entry {
	private Directory parent;
	private LocalDateTime created;
	private LocalDateTime lastUpdated;
	private LocalDateTime lastAccessed;
	private String name;

	public Entry(Directory parent, String name) {
		this.parent = parent;
		this.name = name;
		this.created = LocalDateTime.now();
		this.lastAccessed = LocalDateTime.now();
		this.lastAccessed = LocalDateTime.now();
	}

	public String getFullPath() {
		if (parent == null) {
			return name;
		} else {
			return parent.getFullPath() + "/" + name;
		}
	}

	public boolean delete() {
		if (parent == null) return false;
		return parent.deleteEntry(this);
	}

	public abstract int size();

	public LocalDateTime getCreated() {
		return created;
	}

	public LocalDateTime getLastUpdated() {
		return lastUpdated;
	}

	public LocalDateTime getLastAccessed() {
		return lastAccessed;
	}

	public void changeName(String name) {
		this.name = name;
	}

	public String getName() {
		return name;
	}

	public void setLastUpdated(LocalDateTime lastUpdated) {
		this.lastUpdated = lastUpdated;
	}
}

oop_File.java

package oop;

/**
 * @author Bazlur Rahman Rokon
 * @since 3/31/17.
 */
public class File extends Entry {
	private String content;
	private int size;

	public File(Directory parent, String name, int size) {
		super(parent, name);
		this.size = size;
	}

	@Override
	public int size() {
		return size;
	}

	public String getContent() {
		return content;
	}

	public void setContent(String content) {
		this.content = content;
	}
}

oop_FileDemo.java

package oop;

/**
 * @author Bazlur Rahman Rokon
 * @since 3/31/17.
 */
public class FileDemo {
	public static void main(String[] args) {

		Directory root = new Directory(null, "root");
		File file = new File(root, "movie.mpg", 10);
		root.addEntry(file);
		System.out.println(root.size());

		System.out.println(file.getFullPath());
	}
}