Java Validation - Int, String, Char Needed

[modmouse]

I'm after validation for these bellow with an explanation to what I'm trying to attempt for each one.

 public void setPrice(int aPrice)throws DishException
  {
     if (aPrice < 0)
         throw new DishException ("Price cannot not be a negative number");

         price = aPrice;
  }

Only accept numbers, and cannot be empty.

    public void setType(char aType) throws DishException
  {
     if(aType == 0)
       throw new DishException ("A dish type must be entered");

       type = aType;
  }

Only accept one letter from the following [s,m,d or S,M,D]

  public void setName (String aName)throws DishException
  {
    if(aName.length() == 0)
       throw new DishException ("A dish name must be entered");

       name = aName;
  }

Only allow words no numbers or symbols

Any help would be great B)

[int0x80]

Cool homework, bro.

[Mr-Protocol]

Cool homework, bro.

Yeah, reading the book helps. I haven't done any C in a while to even attempt to help out. Python has spoiled me :)

Whoops, thought it was C. It's Java, I've never coded java so I'm equally screwed lol.