The scanner can also use delimiters other than whitespace. Easy example from Scanner API: The point is to understand the regular expressions (regex) inside the Scanner::useDelimiter. Find an useDelimiter tutorial here. To start with regular expressions here you can find a nice tutorial. Notes
with Scanner you need to check if there is a next line with hasNextLine() so the loop becomes it’s readers that return null on EOF ofcourse in this piece of code this is dependent on whether the input is properly formatted
I always prefer to read input using nextLine() and then parse the string. Using next() will only return what comes before the delimiter (defaults to whitespace). nextLine() automatically moves the scanner down after returning the current line. A useful tool for parsing data from nextLine() would be str.split(“\\s+”). For more information regarding the Scanner class or String class refer to the following links. Scanner: http://docs.oracle.com/javase/7/docs/api/java/util/Scanner.html … Read more
Alright, let’s elaborate with some simplified explanation about the Scanner class. It is a standard Oracle class which you can use by calling the import java.util.Scanner. So let’s make a basic example of the class: Now when you call Scanner input = new Scanner(System.in); you make a new object of the Scanner class (so you make a new “Scanner”) and you store … Read more
Overview of Scanner.hasNextXXX methods java.util.Scanner has many hasNextXXX methods that can be used to validate input. Here’s a brief overview of all of them: hasNext() – does it have any token at all? hasNextLine() – does it have another line of input? For Java primitives hasNextInt() – does it have a token that can be parsed into an int? Also available are hasNextDouble(), hasNextFloat(), hasNextByte(), hasNextShort(), hasNextLong(), and hasNextBoolean() As bonus, there’s … Read more
Scanner is used for parsing tokens from the contents of the stream while BufferedReader just reads the stream and does not do any special parsing. In fact you can pass a BufferedReader to a scanner as the source of characters to parse.
Here you can see the nature of Scanner: double nextDouble() Returns the next token as a double. If the next token is not a float or is out of range, InputMismatchException is thrown. Try to catch the exception UPDATE CASE 1 I tried your code and there is nothing wrong with it. Your are getting that error … Read more
I would recommend making Rock, Paper and Scissors objects. The objects would have the logic of both translating to/from Strings and also “knowing” what beats what. The Java enum is perfect for this. The parseType method can return null if the String is not a valid type. And you code can check if the value is null and if … Read more
NoSuchElementException Thrown by the nextElement method of an Enumeration to indicate that there are no more elements in the enumeration. http://docs.oracle.com/javase/7/docs/api/java/util/NoSuchElementException.html How about this :
You close the second Scanner which closes the underlying InputStream, therefore the first Scanner can no longer read from the same InputStream and a NoSuchElementException results. The solution: For console apps, use a single Scanner to read from System.in. Aside: As stated already, be aware that Scanner#nextInt does not consume newline characters. Ensure that these are consumed before attempting to call nextLine again by using Scanner#newLine(). See: Do not create multiple buffered wrappers on … Read more