// Helene Martin, CSE 142
// Renames all files in a folder to follow a uniform naming convention.
// For example, I renamed pictures in my funny cats picture collection to 
// cat1.jpg, cat2.jpg, etc.

// This is an example of something very practical that we can now do.
// I used the Java API specification for insights: 
// http://docs.oracle.com/javase/7/docs/api/ (search for java 7 api)
import java.util.*;
import java.io.*;

public class RenamePics {
	public static void main(String[] args) {
		// File methods: http://docs.oracle.com/javase/7/docs/api/index.html?java/io/File.html
		File dir = new File("cats/");
		// listFiles() returns an array of Files in the directory
		File[] catPics = dir.listFiles();
		
		for (int i = 0; i < catPics.length; i++) {
			File cat = catPics[i];
			
			// if I don't save the extension (.jpg, for example),
			// then pics won't open in every program
			String name = cat.getName();
			String extension = name.substring(name.length() - 4);
			
			File newName = new File("cats/cat" + (i + 1) + extension);
			// renameTo takes a File as a parameter, not a String!
			cat.renameTo(newName);
		}
	}
}