public static String checkNotEmpty(String string,Object errorMessage){
  if (ExoPlayerLibraryInfo.ASSERTIONS_ENABLED && TextUtils.isEmpty(string)) {
    throw new IllegalArgumentException(String.valueOf(errorMessage));
  }
  return string;
}

public static String checkNotEmpty ( String string , Object errorMessage ) { if ( ExoPlayerLibraryInfo . ASSERTIONS_ENABLED && TextUtils . isEmpty ( string ) ) { throw new IllegalArgumentException ( String . valueOf ( errorMessage ) ) ; } return string ; }
ensures that a string passed as an argument to the calling method is not null or 0 - length .
