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- /*************************************************************************
- * Compilation: javac StdIn.java
- * Execution: java StdIn
- *
- * Reads in data of various types from standard input.
- *
- *************************************************************************/
- import java.io.BufferedInputStream;
- import java.util.Locale;
- import java.util.Scanner;
- /**
- * <i>Standard input</i>. This class provides methods for reading strings
- * and numbers from standard input.
- * <p>
- * The Locale used is: language = English, country = US. This is consistent
- * with the formatting conventions with Java floating-point literals,
- * command-line arguments (via <tt>Double.parseDouble()</tt>)
- * and standard output (via <tt>System.out.print()</tt>). It ensures that
- * standard input works with the input files used in the textbook.
- * <p>
- * For additional documentation, see <a href="http://introcs.cs.princeton.edu/15inout">Section 1.5</a> of
- * <i>Introduction to Programming in Java: An Interdisciplinary Approach</i> by Robert Sedgewick and Kevin Wayne.
- */
- public final class StdIn {
- // assume Unicode UTF-8 encoding
- private static String charsetName = "UTF-8";
- // assume language = English, country = US for consistency with System.out.
- private static Locale usLocale = new Locale("en", "US");
- // the scanner object
- private static Scanner scanner = new Scanner(new BufferedInputStream(System.in), charsetName);
- // static initializer
- static { scanner.useLocale(usLocale); }
- // singleton pattern - can't instantiate
- private StdIn() { }
- /**
- * Is there only whitespace left on standard input?
- */
- public static boolean isEmpty() {
- return !scanner.hasNext();
- }
- /**
- * Return next string from standard input
- */
- public static String readString() {
- return scanner.next();
- }
- /**
- * Return next int from standard input
- */
- public static int readInt() {
- return scanner.nextInt();
- }
- /**
- * Return next double from standard input
- */
- public static double readDouble() {
- return scanner.nextDouble();
- }
- /**
- * Return next float from standard input
- */
- public static float readFloat() {
- return scanner.nextFloat();
- }
- /**
- * Return next short from standard input
- */
- public static short readShort() {
- return scanner.nextShort();
- }
- /**
- * Return next long from standard input
- */
- public static long readLong() {
- return scanner.nextLong();
- }
- /**
- * Return next byte from standard input
- */
- public static byte readByte() {
- return scanner.nextByte();
- }
- /**
- * Return next boolean from standard input, allowing "true" or "1" for true,
- * and "false" or "0" for false
- */
- public static boolean readBoolean() {
- String s = readString();
- if (s.equalsIgnoreCase("true")) return true;
- if (s.equalsIgnoreCase("false")) return false;
- if (s.equals("1")) return true;
- if (s.equals("0")) return false;
- throw new java.util.InputMismatchException();
- }
- /**
- * Does standard input have a next line?
- */
- public static boolean hasNextLine() {
- return scanner.hasNextLine();
- }
- /**
- * Return rest of line from standard input
- */
- public static String readLine() {
- return scanner.nextLine();
- }
- /**
- * Return next char from standard input
- */
- // a complete hack and inefficient - email me if you have a better
- public static char readChar() {
- // (?s) for DOTALL mode so . matches a line termination character
- // 1 says look only one character ahead
- // consider precompiling the pattern
- String s = scanner.findWithinHorizon("(?s).", 1);
- return s.charAt(0);
- }
- /**
- * Return rest of input from standard input
- */
- public static String readAll() {
- if (!scanner.hasNextLine()) return null;
- // reference: http://weblogs.java.net/blog/pat/archive/2004/10/stupid_scanner_1.html
- return scanner.useDelimiter("\\A").next();
- }
- /**
- * Read rest of input as array of ints
- */
- public static int[] readInts() {
- String[] fields = readAll().trim().split("\\s+");
- int[] vals = new int[fields.length];
- for (int i = 0; i < fields.length; i++)
- vals[i] = Integer.parseInt(fields[i]);
- return vals;
- }
- /**
- * Read rest of input as array of doubles
- */
- public static double[] readDoubles() {
- String[] fields = readAll().trim().split("\\s+");
- double[] vals = new double[fields.length];
- for (int i = 0; i < fields.length; i++)
- vals[i] = Double.parseDouble(fields[i]);
- return vals;
- }
- /**
- * Read rest of input as array of strings
- */
- public static String[] readStrings() {
- String[] fields = readAll().trim().split("\\s+");
- return fields;
- }
- /**
- * Unit test
- */
- public static void main(String[] args) {
- System.out.println("Type a string: ");
- String s = StdIn.readString();
- System.out.println("Your string was: " + s);
- System.out.println();
- System.out.println("Type an int: ");
- int a = StdIn.readInt();
- System.out.println("Your int was: " + a);
- System.out.println();
- System.out.println("Type a boolean: ");
- boolean b = StdIn.readBoolean();
- System.out.println("Your boolean was: " + b);
- System.out.println();
- System.out.println("Type a double: ");
- double c = StdIn.readDouble();
- System.out.println("Your double was: " + c);
- System.out.println();
- }
- }
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