The scanner can also use delimiters other than whitespace. Easy example from Scanner API: String input = “1 fish 2 fish red fish blue fish”; // \\s* means 0 or more repetitions of any whitespace character // fish is the pattern to find Scanner s = new Scanner(input).useDelimiter(“\\s*fish\\s*”); System.out.println(s.nextInt()); // prints: 1 System.out.println(s.nextInt()); // prints: … Read more
This has really puzzled me for a while but this is what I found in the end. When you call, sc.close() in first method, it not only closes your scanner but closes your System.in input stream as well. You can verify it by printing its status at very top of the second method as : … Read more
The most straight-forward looking approach will just use readLine() which is part of Predef. however that is rather ugly as you need to check for eventual null value: object ScannerTest { def main(args: Array[String]) { var ok = true while (ok) { val ln = readLine() ok = ln != null if (ok) println(ln) } … Read more
I think your problem is that int selection = scanner.nextInt(); reads just the number, not the end of line or anything after the number. When you declare String sentence = scanner.nextLine(); This reads the remainder of the line with the number on it (with nothing after the number I suspect) Try placing a scanner.nextLine(); after … Read more
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+”). String data = scanner.nextLine(); String[] pieces = … Read more
You could take the first character from Scanner.next: char c = reader.next().charAt(0); To consume exactly one character you could use: char c = reader.findInLine(“.”).charAt(0); To consume strictly one character you could use: char c = reader.next(“.”).charAt(0);
They’re essentially horses for courses. Scanner is designed for cases where you need to parse a string, pulling out data of different types. It’s very flexible, but arguably doesn’t give you the simplest API for simply getting an array of strings delimited by a particular expression. String.split() and Pattern.split() give you an easy syntax for … Read more
A simple example to illustrate how java.util.Scanner works would be reading a single integer from System.in. It’s really quite simple. Scanner sc = new Scanner(System.in); int i = sc.nextInt(); To retrieve a username I would probably use sc.nextLine(). System.out.println(“Enter your username: “); Scanner scanner = new Scanner(System.in); String username = scanner.nextLine(); System.out.println(“Your username is ” … 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.
That’s because the Scanner.nextInt method does not read the newline character in your input created by hitting “Enter,” and so the call to Scanner.nextLine returns after reading that newline. You will encounter the similar behaviour when you use Scanner.nextLine after Scanner.next() or any Scanner.nextFoo method (except nextLine itself). Workaround: Either put a Scanner.nextLine call after … Read more