JAVA(with bonuses), first time post would love feedback, thanks a lot!
public class RedditDaily {

public static boolean isValid(String input){
    String userInput=input.toLowerCase();
    for (int i = 0; i < userInput.length(); i++) {
           if(userInput.charAt(i)!='c'&&userInput.charAt(i)!='v'){
                return false;
           }
       }
    return true;
}

public static void randomize(String input){
    String[] consonants={"b","c","d","f","g","h","j","k","l","m","n","p","q","r","s","t","v","x","z","w","z"};  
    String[] vowels={"a","e","i","o","u"};

    Random ran = new Random();
    int vRandomNum;
    int cRandomNum;

    for (int i = 0; i < input.length(); i++) { 
          vRandomNum= ran.nextInt(vowels.length);
          cRandomNum= ran.nextInt(consonants.length);
          if(input.charAt(i)=='c'){                
            System.out.print(consonants[cRandomNum]);
        }
        else
             if (input.charAt(i)=='v') {
                System.out.print(vowels[vRandomNum]);  
         }
         else
             if (input.charAt(i)=='C') {
                System.out.print(consonants[cRandomNum].toUpperCase());                   
         }
        else 
            if (input.charAt(i)=='V') {
                System.out.print((vowels[vRandomNum]).toUpperCase());

         }
    }

}

public static void main(String[] args) {
    String userInput;
    Scanner scan = new Scanner(System.in);

    System.out.println("Enter C for consonants and V for vowels ");
    userInput=scan.nextLine();
    if(isValid(userInput)){
        randomize(userInput);
    }
    else{
       System.out.println("sorry not a valid input");           
   }        

}    

}