code: public boolean isValid(MinecraftDirectory dir) throws IOException, NoSuchAlgorithmException {
  		return ChecksumUtils.verify(dir.getAsset(this), getHash(), "SHA-1", size);
  	}
docs: Validates the asset in the given mcdir.
  <p>
  This method checks the size and hash of the asset. If, one of them
  mismatches, or the asset file doesn't exist, this method will return
  false. Otherwise, this method will return true.
  
  @param dir the mcdir where the asset is in
  @return true if, and only if, the asset is valid
  @throws IOException if an i/o error occurs
  @throws NoSuchAlgorithmException if the default hash algorithm SHA-1
  doesn't exist