package edu.princeton.cs.introcs;
/*************************************************************************
* Compilation: javac StdIn.java
* Execution: java StdIn (interactive test of basic functionality)
*
* Reads in data of various types from standard input.
*
*************************************************************************/
import java.util.ArrayList;
import java.util.InputMismatchException;
import java.util.Locale;
import java.util.Scanner;
import java.util.regex.Pattern;
/**
* The <tt>StdIn</tt> class provides static methods for reading strings
* and numbers from standard input. 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.
* <p>
* For uniformity across platforms, this class uses <tt>Locale.US</tt>
* for the locale and <tt>"UTF-8"</tt> for the character-set encoding.
* The English language locale is consistent with the formatting conventions
* for Java floating-point literals, command-line arguments
* (via {@link Double#parseDouble(String)}) and standard output.
* <p>
* Like {@link Scanner}, reading a <em>token</em> also consumes preceding Java
* whitespace; reading a line consumes the following end-of-line
* delimeter; reading a character consumes nothing extra.
* <p>
* Whitespace is defined in {@link Character#isWhitespace(char)}. Newlines
* consist of \n, \r, \r\n, and Unicode hex code points 0x2028, 0x2029, 0x0085;
* see <tt><a href="http://www.docjar.com/html/api/java/util/Scanner.java.html">
* Scanner.java</a></tt> (NB: Java 6u23 and earlier uses only \r, \r, \r\n).
* <p>
* See {@link In} for a version that handles input from files, URLs,
* and sockets.
* <p>
* Note that Java's UTF-8 encoding does not recognize the optional byte-order
* mask. If the input begins with the optional byte-order mask, <tt>StdIn</tt>
* will have an extra character <tt>uFEFF</tt> at the beginning.
* For details, see http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4508058.
*
* @author David Pritchard
* @author Robert Sedgewick
* @author Kevin Wayne
*/
public final class StdIn {
// it doesn't make sense to instantiate this class
private StdIn() { }
private static Scanner scanner;
/*** begin: section (1 of 2) of code duplicated from In to StdIn */
// assume Unicode UTF-8 encoding
private static final String CHARSET_NAME = "UTF-8";
// assume language = English, country = US for consistency with System.out.
private static final Locale LOCALE = Locale.US;
// the default token separator; we maintain the invariant that this value
// is held by the scanner's delimiter between calls
private static final Pattern WHITESPACE_PATTERN = Pattern.compile("\\p{javaWhitespace}+");
// makes whitespace characters significant
private static final Pattern EMPTY_PATTERN = Pattern.compile("");
// used to read the entire input
private static final Pattern EVERYTHING_PATTERN = Pattern.compile("\\A");
/*** end: section (1 of 2) of code duplicated from In to StdIn */
/*** begin: section (2 of 2) of code duplicated from In to StdIn,
* with all methods changed from "public" to "public static" ***/
/**
* Is the input empty (except possibly for whitespace)? Use this
* to know whether the next call to {@link #readString()},
* {@link #readDouble()}, etc will succeed.
* @return true if standard input is empty (except possibly
* for whitespae), and false otherwise
*/
public static boolean isEmpty() {
return !scanner.hasNext();
}
/**
* Does the input have a next line? Use this to know whether the
* next call to {@link #readLine()} will succeed. <p> Functionally
* equivalent to {@link #hasNextChar()}.
* @return true if standard input is empty, and false otherwise
*/
public static boolean hasNextLine() {
return scanner.hasNextLine();
}
/**
* Is the input empty (including whitespace)? Use this to know
* whether the next call to {@link #readChar()} will succeed.
* <p>Functionally equivalent to {@link #hasNextLine()}.
* @return true if standard input is empty, and false otherwise
*/
public static boolean hasNextChar() {
scanner.useDelimiter(EMPTY_PATTERN);
boolean result = scanner.hasNext();
scanner.useDelimiter(WHITESPACE_PATTERN);
return result;
}
/**
* Reads and returns the next line, excluding the line separator if present.
* @return the next line, excluding the line separator if present
*/
public static String readLine() {
String line;
try { line = scanner.nextLine(); }
catch (Exception e) { line = null; }
return line;
}
/**
* Reads and returns the next character.
* @return the next character
*/
public static char readChar() {
scanner.useDelimiter(EMPTY_PATTERN);
String ch = scanner.next();
assert (ch.length() == 1) : "Internal (Std)In.readChar() error!"
+ " Please contact the authors.";
scanner.useDelimiter(WHITESPACE_PATTERN);
return ch.charAt(0);
}
/**
* Reads and returns the remainder of the input, as a string.
* @return the remainder of the input, as a string
*/
public static String readAll() {
if (!scanner.hasNextLine())
return "";
String result = scanner.useDelimiter(EVERYTHING_PATTERN).next();
// not that important to reset delimeter, since now scanner is empty
scanner.useDelimiter(WHITESPACE_PATTERN); // but let's do it anyway
return result;
}
/**
* Reads the next token and returns the <tt>String</tt>.
* @return the next <tt>String</tt>
*/
public static String readString() {
return scanner.next();
}
/**
* Reads the next token from standard input, parses it as an integer, and returns the integer.
* @return the next integer on standard input
* @throws InputMismatchException if the next token cannot be parsed as an <tt>int</tt>
*/
public static int readInt() {
return scanner.nextInt();
}
/**
* Reads the next token from standard input, parses it as a double, and returns the double.
* @return the next double on standard input
* @throws InputMismatchException if the next token cannot be parsed as a <tt>double</tt>
*/
public static double readDouble() {
return scanner.nextDouble();
}
/**
* Reads the next token from standard input, parses it as a float, and returns the float.
* @return the next float on standard input
* @throws InputMismatchException if the next token cannot be parsed as a <tt>float</tt>
*/
public static float readFloat() {
return scanner.nextFloat();
}
/**
* Reads the next token from standard input, parses it as a long integer, and returns the long integer.
* @return the next long integer on standard input
* @throws InputMismatchException if the next token cannot be parsed as a <tt>long</tt>
*/
public static long readLong() {
return scanner.nextLong();
}
/**
* Reads the next token from standard input, parses it as a short integer, and returns the short integer.
* @return the next short integer on standard input
* @throws InputMismatchException if the next token cannot be parsed as a <tt>short</tt>
*/
public static short readShort() {
return scanner.nextShort();
}
/**
* Reads the next token from standard input, parses it as a byte, and returns the byte.
* @return the next byte on standard input
* @throws InputMismatchException if the next token cannot be parsed as a <tt>byte</tt>
*/
public static byte readByte() {
return scanner.nextByte();
}
/**
* Reads the next token from standard input, parses it as a boolean,
* and returns the boolean.
* @return the next boolean on standard input
* @throws InputMismatchException if the next token cannot be parsed as a <tt>boolean</tt>:
* <tt>true</tt> or <tt>1</tt> for true, and <tt>false</tt> or <tt>0</tt> for false,
* ignoring case
*/
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 InputMismatchException();
}
/**
* Reads all remaining tokens from standard input and returns them as an array of strings.
* @return all remaining tokens on standard input, as an array of strings
*/
public static String[] readAllStrings() {
// we could use readAll.trim().split(), but that's not consistent
// because trim() uses characters 0x00..0x20 as whitespace
String[] tokens = WHITESPACE_PATTERN.split(readAll());
if (tokens.length == 0 || tokens[0].length() > 0)
return tokens;
// don't include first token if it is leading whitespace
String[] decapitokens = new String[tokens.length-1];
for (int i = 0; i < tokens.length - 1; i++)
decapitokens[i] = tokens[i+1];
return decapitokens;
}
/**
* Reads all remaining lines from standard input and returns them as an array of strings.
* @return all remaining lines on standard input, as an array of strings
*/
public static String[] readAllLines() {
ArrayList<String> lines = new ArrayList<String>();
while (hasNextLine()) {
lines.add(readLine());
}
return lines.toArray(new String[0]);
}
/**
* Reads all remaining tokens from standard input, parses them as integers, and returns
* them as an array of integers.
* @return all remaining integers on standard input, as an array
* @throws InputMismatchException if any token cannot be parsed as an <tt>int</tt>
*/
public static int[] readAllInts() {
String[] fields = readAllStrings();
int[] vals = new int[fields.length];
for (int i = 0; i < fields.length; i++)
vals[i] = Integer.parseInt(fields[i]);
return vals;
}
/**
* Reads all remaining tokens from standard input, parses them as doubles, and returns
* them as an array of doubles.
* @return all remaining doubles on standard input, as an array
* @throws InputMismatchException if any token cannot be parsed as a <tt>double</tt>
*/
public static double[] readAllDoubles() {
String[] fields = readAllStrings();
double[] vals = new double[fields.length];
for (int i = 0; i < fields.length; i++)
vals[i] = Double.parseDouble(fields[i]);
return vals;
}
/*** end: section (2 of 2) of code duplicated from In to StdIn */
// do this once when StdIn is initialized
static {
resync();
}
/**
* If StdIn changes, use this to reinitialize the scanner.
*/
private static void resync() {
setScanner(new Scanner(new java.io.BufferedInputStream(System.in), CHARSET_NAME));
}
private static void setScanner(Scanner scanner) {
StdIn.scanner = scanner;
StdIn.scanner.useLocale(LOCALE);
}
/**
* Reads all remaining tokens, parses them as integers, and returns
* them as an array of integers.
* @return all remaining integers, as an array
* @throws InputMismatchException if any token cannot be parsed as an <tt>int</tt>
* @deprecated For more consistency, use {@link #readAllInts()}
*/
public static int[] readInts() {
return readAllInts();
}
/**
* Reads all remaining tokens, parses them as doubles, and returns
* them as an array of doubles.
* @return all remaining doubles, as an array
* @throws InputMismatchException if any token cannot be parsed as a <tt>double</tt>
* @deprecated For more consistency, use {@link #readAllDoubles()}
*/
public static double[] readDoubles() {
return readAllDoubles();
}
/**
* Reads all remaining tokens and returns them as an array of strings.
* @return all remaining tokens, as an array of strings
* @deprecated For more consistency, use {@link #readAllStrings()}
*/
public static String[] readStrings() {
return readAllStrings();
}
/**
* Interactive test of basic functionality.
*/
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();
}
}
/*************************************************************************
* Copyright 2002-2012, Robert Sedgewick and Kevin Wayne.
*
* This file is part of stdlib-package.jar, which accompanies the textbook
*
* Introduction to Programming in Java: An Interdisciplinary Approach
* by R. Sedgewick and K. Wayne, Addison-Wesley, 2007. ISBN 0-321-49805-4.
*
* http://introcs.cs.princeton.edu
*
*
* stdlib-package.jar is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* stdlib-package.jar is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with stdlib-package.jar. If not, see http://www.gnu.org/licenses.
*************************************************************************/