Class ACMIO 

java.lang.Object
   |
   +----ACMIO
public class ACMIO
extends Object
The ACMIO class has methods for reading some primitive data values from the keyboard and text files, and it has methods to set fieldwidth and precision in formatting Strings for output. The class was designed for use in the ACM Mid-Central Regional Competition, November 6, 1999. See the sample program ACMIOTest.java and sample input file t.txt.

Input method overview

There is a constructor that takes a filename as parameter. For example

             ACMIO fileIn = new ACMIO("problem1.in");
You may instantiate multiple file readers. There is only one keyboard, so a static method returns the only keyboard reader. For example:
             ACMIO stdin = ACMIO.getStdin();
IOExceptions and input in illegal formats cause the program to terminate with an error message to System.err. The illegal input formats are caused by incorrect numeric format or end-of-file where a token was expected.
Most reading methods skip initial whitespace, but there are two methods that do not:

             getChar() reads the next character, and
             getLine() reads a whole line.
Methods with names in the form typeRead skip whitespace and then read an int, long, double, char or String. Examples are intRead() and stringRead(). Note all start with a lowercase letter. Method stringRead() reads the longest String with no whitespace. There are also methods with "ln" added to the end:  intReadln(), longReadln(), doubleReadln(), charReadln() and stringReadln(), which all skip the rest of the line.
Note the distinction between that getLine() and stringReadln().   Both end up after the end of a line, but getLine() returns the rest of the current line, and stringReadln()skips all whitespace, possibly through several empty lines, and skips to the end of the line after the first sequence of non-whitespace characters it finds.
Boolean methods that test the state are isEOLN() and isEOF(), which read ahead to see if the end of a line or the end of the file is next.
Void input skipping methods are skipBlanks(), skipWhitespace(), and skipLine().

String formatting method overview:

To be comparable with output formatting in Pascal and C and C++, there are a group of overloaded static methods to specify the precision of a double and the minimum fieldwidth and left or right justification for any String.

String format(long l, int minimumWidth)
String format(Object o, int minimumWidth)
String format(double d, int minimumWidth)
String format(double d, int minimumWidth, int fractionDigits)

where a positive minimumWidth means right-justify and negative means left-justify, and both are in a field of at least |minimumWidth| columns.
Explicit overloadings for the justification are only given for numbers and for objects, but anything can be converted to a String Object by concatenating it with the empty String: "" + (anything). Examples:

format(123.45678, 7, 2) returns " 123.46", with one blank on the left.
format(123.45678, -7, 2) returns "123.46 ", with one blank on the right.
format(-1234, 8) returns "   -1234", with three blanks on the left.
format("abc", -5) returns "abc  ", with two blanks on the right.

Version:
Sept 16, 1999
Author:
Andrew Harrington (anh@cs.luc.edu)

Constructor Index

o ACMIO(String)
Construct an ACMIO to read from a file.

Method Index

o charRead()
Skip whitespace and read a character.
o charReadln()
Skip whitespace, read a character, and skip the rest of the line.
o doubleRead()
Read a double number.
o doubleReadln()
Read a double value from a complete line.
o format(double, int)
Create a left or right justified String from a double value.
o format(double, int, int)
Format a double as a String with a specified format.
o format(long, int)
Create a left or right justified String from a long value.
o format(Object, int)
Create a left or right justified String from an Object .
o getChar()
Read a character.
o getLine()
Read until the end of the current line.
o getStdin()
Returns the ACMIO object that reads from System.in.
o intRead()
Read an int value.
o intReadln()
Read an int value from a complete line.
o isEOF()
Determine whether the last character of the file has been read.
o isEOLN()
Determine whether the next input character is an end of line or end of file.
o longRead()
Read a long value.
o longReadln()
Read a long value from a complete line.
o skipBlanks()
Read and discard blanks.
o skipLine()
Read and discard the rest of the current input line.
o skipWhitespace()
Read and discard whitespace: blanks, tabs, and newlines.
o stringRead()
Read the next whitespace-delimited String.
o stringReadln()
Read the next whitespace-delimited String, and skip the rest of the line it is on.

Constructors

o ACMIO 
 public ACMIO(String filename)
Construct an ACMIO to read from a file.

Parameters:
filename - file to read from.
Abort if the file cannot be opened to read.

Methods

o getStdin 
 public static ACMIO getStdin()
Returns the ACMIO object that reads from System.in.

Returns:
ACMIO object that reads from System.in
o skipWhitespace 
 public void skipWhitespace()
Read and discard whitespace: blanks, tabs, and newlines.

o skipBlanks 
 public void skipBlanks()
Read and discard blanks.

o skipLine 
 public void skipLine()
Read and discard the rest of the current input line.

o getLine 
 public String getLine()
Read until the end of the current line.

Returns:
a String with all characters other that '\r' or '\n' until the end of the line, or end-of-file if that comes first.
o getChar 
 public char getChar()
Read a character.

Returns:
a character read
Abort if tried to read at end-of-file.
o charRead 
 public char charRead()
Skip whitespace and read a character.

Returns:
a character read that is not whitespace
Abort if there was only whitespace until the end-of-file.
o charReadln 
 public char charReadln()
Skip whitespace, read a character, and skip the rest of the line.

Returns:
a character read that is not whitespace
Abort if there was only whitespace until the end-of-file.
o doubleRead 
 public double doubleRead()
Read a double number.

Returns:
a double number that's been read
Parsing details: Skip whitespace and then read an optional sign, 0 or more digits, an optional '.' and 0 or more digits, and an optional exponent including an 'e' or 'E', optional sign, and digits. The first character not fitting this pattern is left in the input stream. The extracted string is converted using Double.valueOf.
Abort if the conversion to a double causes an exception.
o doubleReadln 
 public double doubleReadln()
Read a double value from a complete line.

Returns:
a double value that's been read
Note:
This method is identical to doubleRead() with skipLine() called just before returning.
o intRead 
 public int intRead()
Read an int value.

Returns:
an int that has been read
Parsing details: Skip whitespace and then read an optional sign and digits. The first character not fitting this pattern is left in the input stream. The extracted string is converted using Integer.parseInt.
Abort if the conversion to an int causes an exception.
o intReadln 
 public int intReadln()
Read an int value from a complete line.

Returns:
an int that has been read
Note:
This method is identical to intRead() with skipLine() called just before returning.
o longRead 
 public long longRead()
Read a long value.

Returns:
a long value that has been read
Parsing details: Skip whitespace and then read an optional sign and digits. The first character not fitting this pattern is left in the input stream. The extracted string is converted using Long.parseInt.
Abort if the conversion to a long causes an exception.
o longReadln 
 public long longReadln()
Read a long value from a complete line.

Returns:
a long value that has been read
Note:
This method is identical to longRead() with skipLine() called just before returning.
o stringRead 
 public String stringRead()
Read the next whitespace-delimited String.

Returns:
a String of non-whitespace characters read
Abort if there are no non-whitespace characters until end-of-file.
o stringReadln 
 public String stringReadln()
Read the next whitespace-delimited String, and skip the rest of the line it is on.

Returns:
a String of non-whitespace characters read
Abort if there are no non-whitespace characters until end-of-file.
o isEOF 
 public boolean isEOF()
Determine whether the last character of the file has been read.

Returns:
true if all characters up to but not necessaily including EOF have been read.
o isEOLN 
 public boolean isEOLN()
Determine whether the next input character is an end of line or end of file.

Returns:
true if the next input character is '\n' or '\r', or if isEOF()
o format 
 public static String format(double d,
                             int minimumWidth,
                             int fractionDigits)
Format a double as a String with a specified format.

Parameters:
d - the number to be printed
minimumWidth - |minimumWidth| is the minimum number of characters in the entire output, and the positive or negative sign indicates right or left justification.
fractionDigits - the number of digits to print, with rounding, on the right side of the decimal point. A negatine fractionDigits is treated like 0. No decimal point is printed if fractionDigits is 0.
o format 
 public static String format(Object o,
                             int minimumWidth)
Create a left or right justified String from an Object .

Parameters:
o - the Object to be printed
minimumWidth - |minimumWidth| is the minimum number of characters in the entire output, and the positive or negative sign indicates right or left justification.
o format 
 public static String format(double d,
                             int minimumWidth)
Create a left or right justified String from a double value.

Parameters:
d - the number to be printed
minimumWidth - |minimumWidth| is the minimum number of characters in the entire output, and the positive or negative sign indicates right or left justification.
o format 
 public static String format(long n,
                             int minimumWidth)
Create a left or right justified String from a long value.

Parameters:
n - the number to be printed
minimumWidth - |minimumWidth| is the minimum number of characters in the entire output, and the positive or negative sign indicates right or left justification.