il.ac.tau.cs.software1.simple_io
Class LineInput

java.lang.Object
 |
 +--il.ac.tau.cs.software1.simple_io.LineInput

public class LineInput

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

LineInput()

Method Summary

static int	read() Reads the first byte in the input stream and returns that byte as an int.
static byte	readByte() Reads the first string of nonwhite characters and returns the byte value it represents.
static char	readChar() Reads the next input character and returns that character.
static double	readDouble() Reads the first string of nonwhite characters and returns the double value it represents.
static float	readFloat() Reads the first string of nonwhite characters and returns the float value it represents.
static int	readInt() Reads the first string of nonwhite characters and returns the int value it represents.
static java.lang.String	readLine() Reads a line of text and returns that line as a String value.
static java.lang.String	readLine(java.lang.String msg) Reads a line of text and returns that line as a String value.
static boolean	readLineBoolean() Returns a boolean value according to the input string.
static boolean	readLineBoolean(java.lang.String msg) Returns a boolean value according to the input string.
static byte	readLineByte() Reads and returns a number as a value of type byte.
static double	readLineDouble() Reads and returns a number as a value of type double.
static double	readLineDouble(java.lang.String msg) Reads and returns a number as a value of type double.
static float	readLineFloat() Reads and returns a number as a value of type float.
static float	readLineFloat(java.lang.String msg) Reads and returns a number as a value of type float.
static int	readLineInt() Reads and returns a number as a value of type int.
static int	readLineInt(java.lang.String msg) Reads and returns a number as a value of type int.
static long	readLineLong() Reads and returns a number as a value of type long.
static long	readLineLong(java.lang.String msg) Reads and returns a number as a value of type long.
static char	readLineNonwhiteChar() Reads the first nonwhite character on a line and returns that character.
static char	readLineNonwhiteChar(java.lang.String msg) Reads the first nonwhite character on a line and returns that character.
static short	readLineShort() Reads and returns the number as a value of type short.
static java.lang.String	readLineWord() Reads the first string of nonwhite characters on a line and returns that string.
static java.lang.String	readLineWord(java.lang.String msg) Reads the first string of nonwhite characters on a line and returns that string.
static long	readLong() Reads the first string of nonwhite characters and returns the long value it represents.
static char	readNonwhiteChar() Reads the next nonwhite input character and returns that character.
static short	readShort() Reads the first string of nonwhite characters and returns the short value it represents.
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

LineInput

public LineInput()

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.

Returns:

The line read as a String value.

readLine

public static java.lang.String readLine(java.lang.String msg)

Reads a line of text and returns that line as a String value.

Parameters:

msg - The request message to show to the user.

Returns:

The line read as a String value.

See Also:

readLine()

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.

Returns:

The first String of nonwhite characters on a line.

readLineWord

public static java.lang.String readLineWord(java.lang.String msg)

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.

Parameters:

msg - The request message to show to the user.

Returns:

The first String of nonwhite characters on a line.

See Also:

readLineWord()

readLineInt

public static int readLineInt()

Reads and returns a number as a value of type int. 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. 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.

Returns:

The number read as int value.

readLineInt

public static int readLineInt(java.lang.String msg)

Reads and returns a number as a value of type int. The rest of the line is discarded.

Parameters:

msg - The request message to show to the user.

Returns:

The number read as int value.

See Also:

readLineInt()

readLineLong

public static long readLineLong()

Reads and returns a number as a value of type long. 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. 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.

Returns:

The number read as long value.

readLineLong

public static long readLineLong(java.lang.String msg)

Reads and returns a number as a value of type long. The rest of the line is discarded.

Parameters:

msg - The request message to show to the user.

Returns:

The number read as long value.

See Also:

readLineLong()

readLineDouble

public static double readLineDouble()

Reads and returns a number as a value of type double. 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. 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.

Returns:

The number read as double value.

readLineDouble

public static double readLineDouble(java.lang.String msg)

Reads and returns a number as a value of type double. The rest of the line is discarded. If the input is

Parameters:

msg - The request message to show to the user.

Returns:

The number read as double value.

See Also:

readLineDouble()

readLineFloat

public static float readLineFloat()

Reads and returns a number as a value of type float. 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. 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.

Returns:

The number read as float value.

readLineFloat

public static float readLineFloat(java.lang.String msg)

Reads and returns a number as a value of type float. The rest of the line is discarded.

Parameters:

msg - The request message to show to the user.

Returns:

The number read as float value.

See Also:

readLineFloat()

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.

Returns:

The first nonwhite character.

readLineNonwhiteChar

public static char readLineNonwhiteChar(java.lang.String msg)

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.

Parameters:

msg - The request message to show to the user.

Returns:

The first nonwhite character.

See Also:

readLineNonwhiteChar()

readLineBoolean

public static boolean readLineBoolean()

Returns a boolean value according to the input string. 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.

Returns:

A boolean value according to the input string.

readLineBoolean

public static boolean readLineBoolean(java.lang.String msg)

Returns a boolean value according to the input string. If the input word is "true" or "t", then true is returned. If the input word is "false" or "f", then false is returned.

Parameters:

msg - The request message to show to the user.

Returns:

A boolean value according to the input string.

See Also:

readLineBoolean()

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.

Returns:

The next input character.

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.

Returns:

The next nonwhite input character.

readInt

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

Reads the first string of nonwhite characters and returns the int value it represents. Precondition: The next input in the stream consists of an int value, possibly preceded by white space, but definitely followed by white space. The reading 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.

Returns:

The int value of the first string of nonwhite characters.

Throws:

java.lang.NumberFormatException - is thrown if the next word does not represent an int value

readLong

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

Reads the first string of nonwhite characters and returns the long value it represents. Precondition: The next input in the stream consists of an long value, possibly preceded by white space, but definitely followed by white space. The reading 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.

Returns:

The long value of the first string of nonwhite characters.

Throws:

java.lang.NumberFormatException - is thrown if the next word does not represent a long value

readDouble

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

Reads the first string of nonwhite characters and returns the double value it represents. Precondition: The next input in the stream consists of an double value, possibly preceded by white space, but definitely followed by white space. The reading 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.

Returns:

The double value of the first string of nonwhite characters.

Throws:

java.lang.NumberFormatException - is thrown if the next word does not represent a double value

readFloat

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

Reads the first string of nonwhite characters and returns the float value it represents. Precondition: The next input in the stream consists of an float value, possibly preceded by white space, but definitely followed by white space. The reading 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.

Returns:

The float value of the first string of nonwhite characters.

Throws:

java.lang.NumberFormatException - is thrown if the next word does not represent a float value

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.

Returns:

the first String of nonwhite characters.

readLineByte

public static byte readLineByte()

Reads and returns a number as a value of type byte. 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. 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.

Returns:

The number read as double value.

readLineShort

public static short readLineShort()

Reads and returns the number as a value of type short. 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. 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.

Returns:

The number read as double value.

readByte

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

Reads the first string of nonwhite characters and returns the byte value it represents. Precondition: The next input in the stream consists of an byte value, possibly preceded by white space, but definitely followed by white space. The reading 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.

Returns:

The byte value of the first string of nonwhite characters.

Throws:

java.lang.NumberFormatException - is thrown if the next word does not represent a byte value

readShort

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

Reads the first string of nonwhite characters and returns the short value it represents. Precondition: The next input in the stream consists of an short value, possibly preceded by white space, but definitely followed by white space. The reading 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.

Returns:

The short value of the first string of nonwhite characters.

Throws:

java.lang.NumberFormatException - is thrown if the next word does not represent a short value

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.

Returns:

The first byte in the input stream as an int.