IO
Class SavitchIn

java.lang.Object
  |
  +--IO.SavitchIn

public class SavitchIn

extends java.lang.Object

Class for simple console input. A class designed primarily for simple keyboard input of the form one input value per line. If the user enters an improper input, i.e., an input of the wrong type or a blank line, then the user is prompted to reenter the input and given a brief explanation of what is required. Also includes some additional methods to input single numbers, words, and characters, without going to the next line.

Constructor Summary

SavitchIn()

Method Summary

static int	read() Reads the first byte in the input stream and returns that byte as an int.
static byte	readByte()
static char	readChar() Reads the next input character and returns that character.
static double	readDouble() Precondition: The next input consists of a double value, possibly preceded by white space, but definitely followed by white space.
static float	readFloat() Precondition: The next input consists of a float value, possibly preceded by white space, but definitely followed by white space.
static int	readInt() Precondition: The next input in the stream consists of an int value, possibly preceded by white space, but definitely followed by white space.
static java.lang.String	readLine() Reads a line of text and returns that line as a String value.
static boolean	readLineBoolean() Input should consist of a single word on a line, possibly surrounded by white space.
static byte	readLineByte() Precondition: The user has entered a number of type byte on a line by itself, except that there may be white space before and/or after the number.
static double	readLineDouble() Precondition: The user has entered a number of type double on a line by itself, except that there may be white space before and/or after the number.
static float	readLineFloat() Precondition: The user has entered a number of type float on a line by itself, except that there may be white space before and/or after the number.
static int	readLineInt() Precondition: The user has entered a number of type int on a line by itself, except that there may be white space before and/or after the number.
static long	readLineLong() Precondition: The user has entered a number of type long on a line by itself, except that there may be white space before and/or after the number.
static char	readLineNonwhiteChar() Reads the first nonwhite character on a line and returns that character.
static short	readLineShort() Precondition: The user has entered a number of type short on a line by itself, except that there may be white space before and/or after the number.
static java.lang.String	readLineWord() Reads the first string of nonwhite characters on a line and returns that string.
static long	readLong() Precondition: The next input consists of a long value, possibly preceded by white space, but definitely followed by white space.
static char	readNonwhiteChar() Reads the next nonwhite input character and returns that character.
static short	readShort()
static java.lang.String	readWord() Reads the first string of nonwhite characters and returns that string.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SavitchIn

public SavitchIn()

Method Detail

readLine

public static java.lang.String readLine()

Reads a line of text and returns that line as a String value. The end of a line must be indicated either by a new-line character '\n' or by a carriage return '\r' followed by a new-line character '\n'. (Almost all systems do this automatically. So, you need not worry about this detail.) Neither the '\n', nor the '\r' if present, are part of the string returned. This will read the rest of a line if the line is already partially read.

readLineWord

public static java.lang.String readLineWord()

Reads the first string of nonwhite characters on a line and returns that string. The rest of the line is discarded. If the line contains only white space, then the user is asked to reenter the line.

readLineInt

public static int readLineInt()

Precondition: The user has entered a number of type int on a line by itself, except that there may be white space before and/or after the number. Action: Reads and returns the number as a value of type int. The rest of the line is discarded. If the input is not entered correctly, then in most cases, the user will be asked to reenter the input. In particular, this applies to incorrect number formats and blank lines.

readLineLong

public static long readLineLong()

Precondition: The user has entered a number of type long on a line by itself, except that there may be white space before and/or after the number. Action: Reads and returns the number as a value of type long. The rest of the line is discarded. If the input is not entered correctly, then in most cases, the user will be asked to reenter the input. In particular, this applies to incorrect number formats and blank lines.

readLineDouble

public static double readLineDouble()

Precondition: The user has entered a number of type double on a line by itself, except that there may be white space before and/or after the number. Action: Reads and returns the number as a value of type double. The rest of the line is discarded. If the input is not entered correctly, then in most cases, the user will be asked to reenter the input. In particular, this applies to incorrect number formats and blank lines.

readLineFloat

public static float readLineFloat()

Precondition: The user has entered a number of type float on a line by itself, except that there may be white space before and/or after the number. Action: Reads and returns the number as a value of type float. The rest of the line is discarded. If the input is not entered correctly, then in most cases, the user will be asked to reenter the input. In particular, this applies to incorrect number formats and blank lines.

readLineNonwhiteChar

public static char readLineNonwhiteChar()

Reads the first nonwhite character on a line and returns that character. The rest of the line is discarded. If the line contains only white space, then the user is asked to reenter the line.

readLineBoolean

public static boolean readLineBoolean()

Input should consist of a single word on a line, possibly surrounded by white space. The line is read and discarded. If the input word is "true" or "t", then true is returned. If the input word is "false" or "f", then false is returned. Uppercase and lowercase letters are considered equal. If the user enters anything else (e.g., multiple words or different words), then the user is asked to reenter the input.

readChar

public static char readChar()

Reads the next input character and returns that character. The next read takes place on the same line where this one left off.

readNonwhiteChar

public static char readNonwhiteChar()

Reads the next nonwhite input character and returns that character. The next read takes place immediately after the character read.

readInt

public static int readInt()
                   throws java.lang.NumberFormatException

Precondition: The next input in the stream consists of an int value, possibly preceded by white space, but definitely followed by white space. Action: Reads the first string of nonwhite characters and returns the int value it represents. Discards the first whitespace character after the word. The next read takes place immediately after the discarded whitespace. In particular, if the word is at the end of a line, the next reading will take place starting on the next line. If the next word does not represent an int value, a NumberFormatException is thrown.

java.lang.NumberFormatException

readLong

public static long readLong()
                     throws java.lang.NumberFormatException

Precondition: The next input consists of a long value, possibly preceded by white space, but definitely followed by white space. Action: Reads the first string of nonwhite characters and returns the long value it represents. Discards the first whitespace character after the string read. The next read takes place immediately after the discarded whitespace. In particular, if the string read is at the end of a line, the next reading will take place starting on the next line. If the next word does not represent a long value, a NumberFormatException is thrown.

java.lang.NumberFormatException

readDouble

public static double readDouble()
                         throws java.lang.NumberFormatException

Precondition: The next input consists of a double value, possibly preceded by white space, but definitely followed by white space. Action: Reads the first string of nonwhitespace characters and returns the double value it represents. Discards the first whitespace character after the string read. The next read takes place immediately after the discarded whitespace. In particular, if the string read is at the end of a line, the next reading will take place starting on the next line. If the next word does not represent a double value, a NumberFormatException is thrown.

java.lang.NumberFormatException

readFloat

public static float readFloat()
                       throws java.lang.NumberFormatException

Precondition: The next input consists of a float value, possibly preceded by white space, but definitely followed by white space. Action: Reads the first string of nonwhite characters and returns the float value it represents. Discards the first whitespace character after the string read. The next read takes place immediately after the discarded whitespace. In particular, if the string read is at the end of a line, the next reading will take place starting on the next line. If the next word does not represent a float value, a NumberFormatException is thrown.

java.lang.NumberFormatException

readWord

public static java.lang.String readWord()

Reads the first string of nonwhite characters and returns that string. Discards the first whitespace character after the string read. The next read takes place immediately after the discarded whitespace. In particular, if the string read is at the end of a line, the next reading will take place starting on the next line. Note, that if it receives blank lines, it will wait until it gets a nonwhitespace character.

readLineByte

public static byte readLineByte()

Precondition: The user has entered a number of type byte on a line by itself, except that there may be white space before and/or after the number. Action: Reads and returns the number as a value of type byte. The rest of the line is discarded. If the input is not entered correctly, then in most cases, the user will be asked to reenter the input. In particular, this applies to incorrect number formats and blank lines.

readLineShort

public static short readLineShort()

Precondition: The user has entered a number of type short on a line by itself, except that there may be white space before and/or after the number. Action: Reads and returns the number as a value of type short. The rest of the line is discarded. If the input is not entered correctly, then in most cases, the user will be asked to reenter the input. In particular, this applies to incorrect number formats and blank lines.

readByte

public static byte readByte()
                     throws java.lang.NumberFormatException

java.lang.NumberFormatException

readShort

public static short readShort()
                       throws java.lang.NumberFormatException

java.lang.NumberFormatException

read

public static int read()

Reads the first byte in the input stream and returns that byte as an int. The next read takes place where this one left off. This read is the same as System.in.read(), except that it catches IOExceptions.