This is a java program that takes a filepath (to a folder... arg1) and randomly renames the files in the folder with a UUID, each randomly renamed file is given the same extension (arg2).

filenameScrambler.java

package main;
import java.io.File;
import java.util.UUID;

/*
* This is a java program that takes a filepath (to a folder... arg1)
* and randomly renames the files in the folder with a UUID, each 
* randomly renamed file is given  the same extension (arg2).
*
* 1st argument is "/the/filepath"
* 2nd argument is ".fileextension"
*/

public class Main {

	public static void main(String[] args) {
		String filepath = args[0];
		String extension = args[1];
		File sourceFolder = new File(filepath);
		File[] fileHandles = getFileHandlesInFolder(sourceFolder);
		int numFiles = getNumFilesInFolder(sourceFolder);
		String[] newFileNames = generateNRandomNames(numFiles);
		for (int i = 0; i < numFiles; i++){
			fileHandles[i].renameTo(new File(filepath + newFileNames[i] + extension));
		}
	}
	public static File[] getFileHandlesInFolder(File sourceFolder){
		return sourceFolder.listFiles();
	}
	public static int getNumFilesInFolder(File sourceFolder){
		return sourceFolder.listFiles().length;
	}
	public static String[] generateNRandomNames(int numNames){
		String[] namesArray = new String[numNames];
		for (int i = 0; i < numNames; i++){
			namesArray[i] = generateRandomName();
		}
		return namesArray;
	}
	public static String generateRandomName(){
		return UUID.randomUUID().toString();
	}
}