edu.princeton.cs.introcs.In Maven / Gradle / Ivy
package edu.princeton.cs.introcs;
/*************************************************************************
* Compilation: javac In.java
* Execution: java In (basic test --- see source for required files)
*
* Reads in data of various types from standard input, files, and URLs.
*
*************************************************************************/
import java.io.BufferedInputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.HttpURLConnection;
import java.net.URLConnection;
import java.util.Scanner;
import java.util.regex.Pattern;
/**
* Input. This class provides methods for reading strings
* and numbers from standard input, file input, URLs, and sockets.
*
* The Locale used is: language = English, country = US. This is consistent
* with the formatting conventions with Java floating-point literals,
* command-line arguments (via {@link Double#parseDouble(String)})
* and standard output.
*
* For additional documentation, see
* Section 3.1 of
* Introduction to Programming in Java: An Interdisciplinary Approach
* by Robert Sedgewick and Kevin Wayne.
*
* Like {@link Scanner}, reading a token also consumes preceding Java
* whitespace, reading a full line consumes
* the following end-of-line delimeter, while reading a character consumes
* nothing extra.
*
* Whitespace is defined in {@link Character#isWhitespace(char)}. Newlines
* consist of \n, \r, \r\n, and Unicode hex code points 0x2028, 0x2029, 0x0085;
* see
* Scanner.java (NB: Java 6u23 and earlier uses only \r, \r, \r\n).
*
* @author David Pritchard
* @author Robert Sedgewick
* @author Kevin Wayne
*/
public final class In {
private Scanner scanner;
/*** begin: section (1 of 2) of code duplicated from In to StdIn */
// assume Unicode UTF-8 encoding
private static final String charsetName = "UTF-8";
// assume language = English, country = US for consistency with System.out.
private static final java.util.Locale usLocale =
new java.util.Locale("en", "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. source:
// http://weblogs.java.net/blog/pat/archive/2004/10/stupid_scanner_1.html
private static final Pattern EVERYTHING_PATTERN
= Pattern.compile("\\A");
/*** end: section (1 of 2) of code duplicated from In to StdIn */
/**
* Create an input stream from standard input.
*/
public In() {
scanner = new Scanner(new BufferedInputStream(System.in), charsetName);
scanner.useLocale(usLocale);
}
/**
* Create an input stream from a socket.
*/
public In(java.net.Socket socket) {
try {
InputStream is = socket.getInputStream();
scanner = new Scanner(new BufferedInputStream(is), charsetName);
scanner.useLocale(usLocale);
}
catch (IOException ioe) {
System.err.println("Could not open " + socket);
}
}
/**
* Create an input stream from a URL.
*/
public In(URL url) {
try {
URLConnection site = url.openConnection();
InputStream is = site.getInputStream();
scanner = new Scanner(new BufferedInputStream(is), charsetName);
scanner.useLocale(usLocale);
}
catch (IOException ioe) {
System.err.println("Could not open " + url);
}
}
/**
* Create an input stream from a file.
*/
public In(File file) {
try {
scanner = new Scanner(file, charsetName);
scanner.useLocale(usLocale);
}
catch (IOException ioe) {
System.err.println("Could not open " + file);
}
}
/**
* Create an input stream from a filename or web page name.
*/
public In(String s) {
try {
// first try to read file from local file system
File file = new File(s);
if (file.exists()) {
scanner = new Scanner(file, charsetName);
scanner.useLocale(usLocale);
return;
}
// next try for files included in jar
URL url = getClass().getResource(s);
// or URL from web
if (url == null) { url = new URL(s); }
URLConnection site = url.openConnection();
// in order to set User-Agent, replace above line with these two
// HttpURLConnection site = (HttpURLConnection) url.openConnection();
// site.addRequestProperty("User-Agent", "Mozilla/4.76");
InputStream is = site.getInputStream();
scanner = new Scanner(new BufferedInputStream(is), charsetName);
scanner.useLocale(usLocale);
}
catch (IOException ioe) {
System.err.println("Could not open " + s);
}
}
/**
* Create an input stream from a given Scanner source; use with
* new Scanner(String) to read from a string.
*
* Note that this does not create a defensive copy, so the
* scanner will be mutated as you read on.
*/
public In(Scanner scanner) {
this.scanner = scanner;
}
/**
* Does the input stream exist?
*/
public boolean exists() {
return scanner != null;
}
/*** 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.
*/
public 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.
Functionally
* equivalent to {@link #hasNextChar()}.
*/
public boolean hasNextLine() {
return scanner.hasNextLine();
}
/**
* Is the input empty (including whitespace)? Use this to know
* whether the next call to {@link #readChar()} will succeed.
Functionally
* equivalent to {@link #hasNextLine()}.
*/
public boolean hasNextChar() {
scanner.useDelimiter(EMPTY_PATTERN);
boolean result = scanner.hasNext();
scanner.useDelimiter(WHITESPACE_PATTERN);
return result;
}
/**
* Read and return the next line.
*/
public String readLine() {
String line;
try { line = scanner.nextLine(); }
catch (Exception e) { line = null; }
return line;
}
/**
* Read and return the next character.
*/
public 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);
}
/**
* Read and return the remainder of the input as a string.
*/
public 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;
}
/**
* Read and return the next string.
*/
public String readString() {
return scanner.next();
}
/**
* Read and return the next int.
*/
public int readInt() {
return scanner.nextInt();
}
/**
* Read and return the next double.
*/
public double readDouble() {
return scanner.nextDouble();
}
/**
* Read and return the next float.
*/
public float readFloat() {
return scanner.nextFloat();
}
/**
* Read and return the next long.
*/
public long readLong() {
return scanner.nextLong();
}
/**
* Read and return the next short.
*/
public short readShort() {
return scanner.nextShort();
}
/**
* Read and return the next byte.
*/
public byte readByte() {
return scanner.nextByte();
}
/**
* Read and return the next boolean, allowing case-insensitive
* "true" or "1" for true, and "false" or "0" for false.
*/
public 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();
}
/**
* Read all strings until the end of input is reached, and return them.
*/
public String[] readAllStrings() {
// we could use readAll.trim().split(), but that's not consistent
// since trim() uses characters 0x00..0x20 as whitespace
String[] tokens = WHITESPACE_PATTERN.split(readAll());
if (tokens.length == 0 || tokens[0].length() > 0)
return tokens;
String[] decapitokens = new String[tokens.length-1];
for (int i = 0; i < tokens.length-1; i++)
decapitokens[i] = tokens[i+1];
return decapitokens;
}
/**
* Read all ints until the end of input is reached, and return them.
*/
public 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;
}
/**
* Read all doubles until the end of input is reached, and return them.
*/
public 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 */
/**
* Close the input stream.
*/
public void close() {
scanner.close();
}
/**
* Reads all ints from a file
* @deprecated Clearer to use
* new In(filename).{@link #readAllInts()}
*/
public static int[] readInts(String filename) {
return new In(filename).readAllInts();
}
/**
* Reads all doubles from a file
* @deprecated Clearer to use
* new In(filename).{@link #readAllDoubles()}
*/
public static double[] readDoubles(String filename) {
return new In(filename).readAllDoubles();
}
/**
* Reads all strings from a file
* @deprecated Clearer to use
* new In(filename).{@link #readAllStrings()}
*/
public static String[] readStrings(String filename) {
return new In(filename).readAllStrings();
}
/**
* Reads all ints from stdin
* @deprecated Clearer to use {@link StdIn#readAllInts()}
*/
public static int[] readInts() {
return new In().readAllInts();
}
/**
* Reads all doubles from stdin
* @deprecated Clearer to use {@link StdIn#readAllDoubles()}
*/
public static double[] readDoubles() {
return new In().readAllDoubles();
}
/**
* Reads all strings from stdin
* @deprecated Clearer to use {@link StdIn#readAllStrings()}
*/
public static String[] readStrings() {
return new In().readAllStrings();
}
/**
* Test client.
*/
public static void main(String[] args) {
In in;
String urlName = "http://introcs.cs.princeton.edu/stdlib/InTest.txt";
// read from a URL
System.out.println("readAll() from URL " + urlName);
System.out.println("---------------------------------------------------------------------------");
try {
in = new In(urlName);
System.out.println(in.readAll());
}
catch (Exception e) { System.out.println(e); }
System.out.println();
// read one line at a time from URL
System.out.println("readLine() from URL " + urlName);
System.out.println("---------------------------------------------------------------------------");
try {
in = new In(urlName);
while (!in.isEmpty()) {
String s = in.readLine();
System.out.println(s);
}
}
catch (Exception e) { System.out.println(e); }
System.out.println();
// read one string at a time from URL
System.out.println("readString() from URL " + urlName);
System.out.println("---------------------------------------------------------------------------");
try {
in = new In(urlName);
while (!in.isEmpty()) {
String s = in.readString();
System.out.println(s);
}
}
catch (Exception e) { System.out.println(e); }
System.out.println();
// read one line at a time from file in current directory
System.out.println("readLine() from current directory");
System.out.println("---------------------------------------------------------------------------");
try {
in = new In("./InTest.txt");
while (!in.isEmpty()) {
String s = in.readLine();
System.out.println(s);
}
}
catch (Exception e) { System.out.println(e); }
System.out.println();
// read one line at a time from file using relative path
System.out.println("readLine() from relative path");
System.out.println("---------------------------------------------------------------------------");
try {
in = new In("../stdlib/InTest.txt");
while (!in.isEmpty()) {
String s = in.readLine();
System.out.println(s);
}
}
catch (Exception e) { System.out.println(e); }
System.out.println();
// read one char at a time
System.out.println("readChar() from file");
System.out.println("---------------------------------------------------------------------------");
try {
in = new In("InTest.txt");
while (!in.isEmpty()) {
char c = in.readChar();
System.out.print(c);
}
}
catch (Exception e) { System.out.println(e); }
System.out.println();
System.out.println();
// read one line at a time from absolute OS X / Linux path
System.out.println("readLine() from absolute OS X / Linux path");
System.out.println("---------------------------------------------------------------------------");
in = new In("/n/fs/introcs/www/java/stdlib/InTest.txt");
try {
while (!in.isEmpty()) {
String s = in.readLine();
System.out.println(s);
}
}
catch (Exception e) { System.out.println(e); }
System.out.println();
// read one line at a time from absolute Windows path
System.out.println("readLine() from absolute Windows path");
System.out.println("---------------------------------------------------------------------------");
try {
in = new In("G:\\www\\introcs\\stdlib\\InTest.txt");
while (!in.isEmpty()) {
String s = in.readLine();
System.out.println(s);
}
System.out.println();
}
catch (Exception e) { System.out.println(e); }
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.
*************************************************************************/