public
final
class
Scanner
extends Object
implements
Iterator<String>,
Closeable
java.lang.Object | |
↳ | java.util.Scanner |
A simple text scanner which can parse primitive types and strings using regular expressions.
A Scanner
breaks its input into tokens using a
delimiter pattern, which by default matches whitespace. The resulting
tokens may then be converted into values of different types using the
various next methods.
For example, this code allows a user to read a number from System.in:
Scanner sc = new Scanner(System.in); int i = sc.nextInt();
As another example, this code allows long
types to be
assigned from entries in a file myNumbers
:
Scanner sc = new Scanner(new File("myNumbers")); while (sc.hasNextLong()) { long aLong = sc.nextLong(); }
The scanner can also use delimiters other than whitespace. This example reads several items in from a string:
String input = "1 fish 2 fish red fish blue fish"; Scanner s = new Scanner(input).useDelimiter("\\s*fish\\s*"); System.out.println(s.nextInt()); System.out.println(s.nextInt()); System.out.println(s.next()); System.out.println(s.next()); s.close();
prints the following output:
1 2 red blue
The same output can be generated with this code, which uses a regular expression to parse all four tokens at once:
String input = "1 fish 2 fish red fish blue fish"; Scanner s = new Scanner(input); s.findInLine("(\\d+) fish (\\d+) fish (\\w+) fish (\\w+)"); MatchResult result = s.match(); for (int i=1; i<=result.groupCount(); i++) System.out.println(result.group(i)); s.close();
The default whitespace delimiter used
by a scanner is as recognized by Character
.isWhitespace
. The reset()
method will reset the value of the scanner's delimiter to the default
whitespace delimiter regardless of whether it was previously changed.
A scanning operation may block waiting for input.
The next()
and hasNext()
methods and their
primitive-type companion methods (such as nextInt()
and
hasNextInt()
) first skip any input that matches the delimiter
pattern, and then attempt to return the next token. Both hasNext
and next methods may block waiting for further input. Whether a
hasNext method blocks has no connection to whether or not its
associated next method will block.
The findInLine(String)
, findWithinHorizon(String, int)
, and skip(String)
methods operate independently of the delimiter pattern. These methods will
attempt to match the specified pattern with no regard to delimiters in the
input and thus can be used in special circumstances where delimiters are
not relevant. These methods may block waiting for more input.
When a scanner throws an InputMismatchException
, the scanner
will not pass the token that caused the exception, so that it may be
retrieved or skipped via some other method.
Depending upon the type of delimiting pattern, empty tokens may be returned. For example, the pattern "\\s+" will return no empty tokens since it matches multiple instances of the delimiter. The delimiting pattern "\\s" could return empty tokens since it only passes one space at a time.
A scanner can read text from any object which implements the Readable
interface. If an invocation of the underlying
readable's read(CharBuffer)
method throws an IOException
then the scanner assumes that the end of the input
has been reached. The most recent IOException thrown by the
underlying readable can be retrieved via the ioException()
method.
When a Scanner
is closed, it will close its input source
if the source implements the Closeable
interface.
A Scanner
is not safe for multithreaded use without
external synchronization.
Unless otherwise mentioned, passing a null
parameter into
any method of a Scanner
will cause a
NullPointerException
to be thrown.
A scanner will default to interpreting numbers as decimal unless a
different radix has been set by using the An instance of this class is capable of scanning numbers in the standard
formats as well as in the formats of the scanner's locale. A scanner's
initial locale is the value returned by the The localized formats are defined in terms of the following parameters,
which for a particular locale are taken from that locale's The strings that can be parsed as numbers by an instance of this class
are specified in terms of the following regular-expression grammar, where
Rmax is the highest digit in the radix being used (for example, Rmax is 9
in base 10).
useRadix(int)
method. The
reset()
method will reset the value of the scanner's radix to
10
regardless of whether it was previously changed.
Localized numbers
getDefault()
method; it may be changed via the useLocale(Locale)
method. The reset()
method will reset the value of the
scanner's locale to the initial locale regardless of whether it was
previously changed.
DecimalFormat
object, df, and its and
DecimalFormatSymbols
object,
dfs.
LocalGroupSeparator
The character used to separate thousands groups,
i.e., dfs. getGroupingSeparator()
LocalDecimalSeparator
The character used for the decimal point,
i.e., dfs. getDecimalSeparator()
LocalPositivePrefix
The string that appears before a positive number (may
be empty), i.e., df. getPositivePrefix()
LocalPositiveSuffix
The string that appears after a positive number (may be
empty), i.e., df. getPositiveSuffix()
LocalNegativePrefix
The string that appears before a negative number (may
be empty), i.e., df. getNegativePrefix()
LocalNegativeSuffix
The string that appears after a negative number (may be
empty), i.e., df. getNegativeSuffix()
LocalNaN
The string that represents not-a-number for
floating-point values,
i.e., dfs. getNaN()
LocalInfinity
The string that represents infinity for floating-point
values, i.e., dfs. getInfinity()
Number syntax
NonASCIIDigit :: | = A non-ASCII character c for which
Character.isDigit (c)
returns true | ||||
Non0Digit :: | = [1-Rmax] | NonASCIIDigit | ||||
Digit :: | = [0-Rmax] | NonASCIIDigit | ||||
GroupedNumeral :: |
| ||||
Numeral :: | = ( ( Digit+ ) | GroupedNumeral ) | ||||
Integer :: | = ( [-+]? ( Numeral ) ) | ||||
| LocalPositivePrefix Numeral LocalPositiveSuffix | |||||
| LocalNegativePrefix Numeral LocalNegativeSuffix | |||||
DecimalNumeral :: | = Numeral | ||||
| Numeral LocalDecimalSeparator Digit* | |||||
| LocalDecimalSeparator Digit+ | |||||
Exponent :: | = ( [eE] [+-]? Digit+ ) | ||||
Decimal :: | = ( [-+]? DecimalNumeral Exponent? ) | ||||
| LocalPositivePrefix DecimalNumeral LocalPositiveSuffix Exponent? | |||||
| LocalNegativePrefix DecimalNumeral LocalNegativeSuffix Exponent? | |||||
HexFloat :: | = [-+]? 0[xX][0-9a-fA-F]*\.[0-9a-fA-F]+ ([pP][-+]?[0-9]+)? | ||||
NonNumber :: | = NaN | LocalNan | Infinity | LocalInfinity | ||||
SignedNonNumber :: | = ( [-+]? NonNumber ) | ||||
| LocalPositivePrefix NonNumber LocalPositiveSuffix | |||||
| LocalNegativePrefix NonNumber LocalNegativeSuffix | |||||
Float :: | = Decimal | ||||
| HexFloat | |||||
| SignedNonNumber |
Whitespace is not significant in the above regular expressions.
Public constructors | |
---|---|
Scanner(Readable source)
Constructs a new |
|
Scanner(InputStream source)
Constructs a new |
|
Scanner(InputStream source, String charsetName)
Constructs a new |
|
Scanner(File source)
Constructs a new |
|
Scanner(File source, String charsetName)
Constructs a new |
|
Scanner(String source)
Constructs a new |
|
Scanner(ReadableByteChannel source)
Constructs a new |
|
Scanner(ReadableByteChannel source, String charsetName)
Constructs a new |
Public methods | |
---|---|
void
|
close()
Closes this scanner. |
Pattern
|
delimiter()
Returns the |
String
|
findInLine(String pattern)
Attempts to find the next occurrence of a pattern constructed from the specified string, ignoring delimiters. |
String
|
findInLine(Pattern pattern)
Attempts to find the next occurrence of the specified pattern ignoring delimiters. |
String
|
findWithinHorizon(Pattern pattern, int horizon)
Attempts to find the next occurrence of the specified pattern. |
String
|
findWithinHorizon(String pattern, int horizon)
Attempts to find the next occurrence of a pattern constructed from the specified string, ignoring delimiters. |
boolean
|
hasNext()
Returns true if this scanner has another token in its input. |
boolean
|
hasNext(String pattern)
Returns true if the next token matches the pattern constructed from the specified string. |
boolean
|
hasNext(Pattern pattern)
Returns true if the next complete token matches the specified pattern. |
boolean
|
hasNextBigDecimal()
Returns true if the next token in this scanner's input can be
interpreted as a |
boolean
|
hasNextBigInteger(int radix)
Returns true if the next token in this scanner's input can be
interpreted as a |
boolean
|
hasNextBigInteger()
Returns true if the next token in this scanner's input can be
interpreted as a |
boolean
|
hasNextBoolean()
Returns true if the next token in this scanner's input can be interpreted as a boolean value using a case insensitive pattern created from the string "true|false". |
boolean
|
hasNextByte()
Returns true if the next token in this scanner's input can be
interpreted as a byte value in the default radix using the
|
boolean
|
hasNextByte(int radix)
Returns true if the next token in this scanner's input can be
interpreted as a byte value in the specified radix using the
|
boolean
|
hasNextDouble()
Returns true if the next token in this scanner's input can be
interpreted as a double value using the |
boolean
|
hasNextFloat()
Returns true if the next token in this scanner's input can be
interpreted as a float value using the |
boolean
|
hasNextInt()
Returns true if the next token in this scanner's input can be
interpreted as an int value in the default radix using the
|
boolean
|
hasNextInt(int radix)
Returns true if the next token in this scanner's input can be
interpreted as an int value in the specified radix using the
|
boolean
|
hasNextLine()
Returns true if there is another line in the input of this scanner. |
boolean
|
hasNextLong()
Returns true if the next token in this scanner's input can be
interpreted as a long value in the default radix using the
|
boolean
|
hasNextLong(int radix)
Returns true if the next token in this scanner's input can be
interpreted as a long value in the specified radix using the
|
boolean
|
hasNextShort()
Returns true if the next token in this scanner's input can be
interpreted as a short value in the default radix using the
|
boolean
|
hasNextShort(int radix)
Returns true if the next token in this scanner's input can be
interpreted as a short value in the specified radix using the
|
IOException
|
ioException()
Returns the |
Locale
|
locale()
Returns this scanner's locale. |
MatchResult
|
match()
Returns the match result of the last scanning operation performed by this scanner. |
String
|
next(Pattern pattern)
Returns the next token if it matches the specified pattern. |
String
|
next()
Finds and returns the next complete token from this scanner. |
String
|
next(String pattern)
Returns the next token if it matches the pattern constructed from the specified string. |
BigDecimal
|
nextBigDecimal()
Scans the next token of the input as a |
BigInteger
|
nextBigInteger()
Scans the next token of the input as a |
BigInteger
|
nextBigInteger(int radix)
Scans the next token of the input as a |
boolean
|
nextBoolean()
Scans the next token of the input into a boolean value and returns that value. |
byte
|
nextByte(int radix)
Scans the next token of the input as a byte. |
byte
|
nextByte()
Scans the next token of the input as a byte. |
double
|
nextDouble()
Scans the next token of the input as a double. |
float
|
nextFloat()
Scans the next token of the input as a float. |
int
|
nextInt()
Scans the next token of the input as an int. |
int
|
nextInt(int radix)
Scans the next token of the input as an int. |
String
|
nextLine()
Advances this scanner past the current line and returns the input that was skipped. |
long
|
nextLong()
Scans the next token of the input as a long. |
long
|
nextLong(int radix)
Scans the next token of the input as a long. |
short
|
nextShort(int radix)
Scans the next token of the input as a short. |
short
|
nextShort()
Scans the next token of the input as a short. |
int
|
radix()
Returns this scanner's default radix. |
void
|
remove()
The remove operation is not supported by this implementation of
|
Scanner
|
reset()
Resets this scanner. |
Scanner
|
skip(String pattern)
Skips input that matches a pattern constructed from the specified string. |
Scanner
|
skip(Pattern pattern)
Skips input that matches the specified pattern, ignoring delimiters. |
String
|
toString()
Returns the string representation of this |
Scanner
|
useDelimiter(Pattern pattern)
Sets this scanner's delimiting pattern to the specified pattern. |
Scanner
|
useDelimiter(String pattern)
Sets this scanner's delimiting pattern to a pattern constructed from
the specified |
Scanner
|
useLocale(Locale locale)
Sets this scanner's locale to the specified locale. |
Scanner
|
useRadix(int radix)
Sets this scanner's default radix to the specified radix. |
Inherited methods | |
---|---|
From
class
java.lang.Object
| |
From
interface
java.util.Iterator
| |
From
interface
java.io.Closeable
| |
From
interface
java.lang.AutoCloseable
|
Scanner (Readable source)
Constructs a new Scanner
that produces values scanned
from the specified source.
Parameters | |
---|---|
source |
Readable :
A character source implementing the Readable
interface
|
Scanner (InputStream source)
Constructs a new Scanner
that produces values scanned
from the specified input stream. Bytes from the stream are converted
into characters using the underlying platform's
default charset.
Parameters | |
---|---|
source |
InputStream :
An input stream to be scanned
|
Scanner (InputStream source, String charsetName)
Constructs a new Scanner
that produces values scanned
from the specified input stream. Bytes from the stream are converted
into characters using the specified charset.
Parameters | |
---|---|
source |
InputStream :
An input stream to be scanned |
charsetName |
String :
The encoding type used to convert bytes from the
stream into characters to be scanned |
Throws | |
---|---|
IllegalArgumentException |
if the specified character set does not exist |
Scanner (File source)
Constructs a new Scanner
that produces values scanned
from the specified file. Bytes from the file are converted into
characters using the underlying platform's
default charset.
Parameters | |
---|---|
source |
File :
A file to be scanned |
Throws | |
---|---|
FileNotFoundException |
if source is not found |
Scanner (File source, String charsetName)
Constructs a new Scanner
that produces values scanned
from the specified file. Bytes from the file are converted into
characters using the specified charset.
Parameters | |
---|---|
source |
File :
A file to be scanned |
charsetName |
String :
The encoding type used to convert bytes from the file
into characters to be scanned |
Throws | |
---|---|
FileNotFoundException |
if source is not found |
IllegalArgumentException |
if the specified encoding is not found |
Scanner (String source)
Constructs a new Scanner
that produces values scanned
from the specified string.
Parameters | |
---|---|
source |
String :
A string to scan
|
Scanner (ReadableByteChannel source)
Constructs a new Scanner
that produces values scanned
from the specified channel. Bytes from the source are converted into
characters using the underlying platform's
default charset.
Parameters | |
---|---|
source |
ReadableByteChannel :
A channel to scan
|
Scanner (ReadableByteChannel source, String charsetName)
Constructs a new Scanner
that produces values scanned
from the specified channel. Bytes from the source are converted into
characters using the specified charset.
Parameters | |
---|---|
source |
ReadableByteChannel :
A channel to scan |
charsetName |
String :
The encoding type used to convert bytes from the
channel into characters to be scanned |
Throws | |
---|---|
IllegalArgumentException |
if the specified character set does not exist |
void close ()
Closes this scanner.
If this scanner has not yet been closed then if its underlying
readable also implements the Closeable
interface then the readable's close method
will be invoked. If this scanner is already closed then invoking this
method will have no effect.
Attempting to perform search operations after a scanner has
been closed will result in an IllegalStateException
.
Pattern delimiter ()
Returns the Pattern
this Scanner
is currently
using to match delimiters.
Returns | |
---|---|
Pattern |
this scanner's delimiting pattern. |
String findInLine (String pattern)
Attempts to find the next occurrence of a pattern constructed from the specified string, ignoring delimiters.
An invocation of this method of the form findInLine(pattern) behaves in exactly the same way as the invocation findInLine(Pattern.compile(pattern)).
Parameters | |
---|---|
pattern |
String :
a string specifying the pattern to search for |
Returns | |
---|---|
String |
the text that matched the specified pattern |
Throws | |
---|---|
IllegalStateException |
if this scanner is closed |
String findInLine (Pattern pattern)
Attempts to find the next occurrence of the specified pattern ignoring
delimiters. If the pattern is found before the next line separator, the
scanner advances past the input that matched and returns the string that
matched the pattern.
If no such pattern is detected in the input up to the next line
separator, then null
is returned and the scanner's
position is unchanged. This method may block waiting for input that
matches the pattern.
Since this method continues to search through the input looking for the specified pattern, it may buffer all of the input searching for the desired token if no line separators are present.
Parameters | |
---|---|
pattern |
Pattern :
the pattern to scan for |
Returns | |
---|---|
String |
the text that matched the specified pattern |
Throws | |
---|---|
IllegalStateException |
if this scanner is closed |
String findWithinHorizon (Pattern pattern, int horizon)
Attempts to find the next occurrence of the specified pattern.
This method searches through the input up to the specified search horizon, ignoring delimiters. If the pattern is found the scanner advances past the input that matched and returns the string that matched the pattern. If no such pattern is detected then the null is returned and the scanner's position remains unchanged. This method may block waiting for input that matches the pattern.
A scanner will never search more than horizon
code
points beyond its current position. Note that a match may be clipped
by the horizon; that is, an arbitrary match result may have been
different if the horizon had been larger. The scanner treats the
horizon as a transparent, non-anchoring bound (see useTransparentBounds(boolean)
and useAnchoringBounds(boolean)
).
If horizon is 0
, then the horizon is ignored and
this method continues to search through the input looking for the
specified pattern without bound. In this case it may buffer all of
the input searching for the pattern.
If horizon is negative, then an IllegalArgumentException is thrown.
Parameters | |
---|---|
pattern |
Pattern :
the pattern to scan for |
horizon |
int
|
Returns | |
---|---|
String |
the text that matched the specified pattern |
Throws | |
---|---|
IllegalStateException |
if this scanner is closed |
IllegalArgumentException |
if horizon is negative |
String findWithinHorizon (String pattern, int horizon)
Attempts to find the next occurrence of a pattern constructed from the specified string, ignoring delimiters.
An invocation of this method of the form findWithinHorizon(pattern) behaves in exactly the same way as the invocation findWithinHorizon(Pattern.compile(pattern, horizon)).
Parameters | |
---|---|
pattern |
String :
a string specifying the pattern to search for |
horizon |
int
|
Returns | |
---|---|
String |
the text that matched the specified pattern |
Throws | |
---|---|
IllegalStateException |
if this scanner is closed |
IllegalArgumentException |
if horizon is negative |
boolean hasNext ()
Returns true if this scanner has another token in its input. This method may block while waiting for input to scan. The scanner does not advance past any input.
Returns | |
---|---|
boolean |
true if and only if this scanner has another token |
Throws | |
---|---|
IllegalStateException |
if this scanner is closed |
See also:
boolean hasNext (String pattern)
Returns true if the next token matches the pattern constructed from the specified string. The scanner does not advance past any input.
An invocation of this method of the form hasNext(pattern) behaves in exactly the same way as the invocation hasNext(Pattern.compile(pattern)).
Parameters | |
---|---|
pattern |
String :
a string specifying the pattern to scan |
Returns | |
---|---|
boolean |
true if and only if this scanner has another token matching the specified pattern |
Throws | |
---|---|
IllegalStateException |
if this scanner is closed |
boolean hasNext (Pattern pattern)
Returns true if the next complete token matches the specified pattern. A complete token is prefixed and postfixed by input that matches the delimiter pattern. This method may block while waiting for input. The scanner does not advance past any input.
Parameters | |
---|---|
pattern |
Pattern :
the pattern to scan for |
Returns | |
---|---|
boolean |
true if and only if this scanner has another token matching the specified pattern |
Throws | |
---|---|
IllegalStateException |
if this scanner is closed |
boolean hasNextBigDecimal ()
Returns true if the next token in this scanner's input can be
interpreted as a BigDecimal
using the
nextBigDecimal()
method. The scanner does not advance past any
input.
Returns | |
---|---|
boolean |
true if and only if this scanner's next token is a valid
BigDecimal |
Throws | |
---|---|
IllegalStateException |
if this scanner is closed |
boolean hasNextBigInteger (int radix)
Returns true if the next token in this scanner's input can be
interpreted as a BigInteger
in the specified radix using
the nextBigInteger()
method. The scanner does not advance past
any input.
Parameters | |
---|---|
radix |
int :
the radix used to interpret the token as an integer |
Returns | |
---|---|
boolean |
true if and only if this scanner's next token is a valid
BigInteger |
Throws | |
---|---|
IllegalStateException |
if this scanner is closed |
boolean hasNextBigInteger ()
Returns true if the next token in this scanner's input can be
interpreted as a BigInteger
in the default radix using the
nextBigInteger()
method. The scanner does not advance past any
input.
Returns | |
---|---|
boolean |
true if and only if this scanner's next token is a valid
BigInteger |
Throws | |
---|---|
IllegalStateException |
if this scanner is closed |
boolean hasNextBoolean ()
Returns true if the next token in this scanner's input can be interpreted as a boolean value using a case insensitive pattern created from the string "true|false". The scanner does not advance past the input that matched.
Returns | |
---|---|
boolean |
true if and only if this scanner's next token is a valid boolean value |
Throws | |
---|---|
IllegalStateException |
if this scanner is closed |
boolean hasNextByte ()
Returns true if the next token in this scanner's input can be
interpreted as a byte value in the default radix using the
nextByte()
method. The scanner does not advance past any input.
Returns | |
---|---|
boolean |
true if and only if this scanner's next token is a valid byte value |
Throws | |
---|---|
IllegalStateException |
if this scanner is closed |
boolean hasNextByte (int radix)
Returns true if the next token in this scanner's input can be
interpreted as a byte value in the specified radix using the
nextByte()
method. The scanner does not advance past any input.
Parameters | |
---|---|
radix |
int :
the radix used to interpret the token as a byte value |
Returns | |
---|---|
boolean |
true if and only if this scanner's next token is a valid byte value |
Throws | |
---|---|
IllegalStateException |
if this scanner is closed |
boolean hasNextDouble ()
Returns true if the next token in this scanner's input can be
interpreted as a double value using the nextDouble()
method. The scanner does not advance past any input.
Returns | |
---|---|
boolean |
true if and only if this scanner's next token is a valid double value |
Throws | |
---|---|
IllegalStateException |
if this scanner is closed |
boolean hasNextFloat ()
Returns true if the next token in this scanner's input can be
interpreted as a float value using the nextFloat()
method. The scanner does not advance past any input.
Returns | |
---|---|
boolean |
true if and only if this scanner's next token is a valid float value |
Throws | |
---|---|
IllegalStateException |
if this scanner is closed |
boolean hasNextInt ()
Returns true if the next token in this scanner's input can be
interpreted as an int value in the default radix using the
nextInt()
method. The scanner does not advance past any input.
Returns | |
---|---|
boolean |
true if and only if this scanner's next token is a valid int value |
Throws | |
---|---|
IllegalStateException |
if this scanner is closed |
boolean hasNextInt (int radix)
Returns true if the next token in this scanner's input can be
interpreted as an int value in the specified radix using the
nextInt()
method. The scanner does not advance past any input.
Parameters | |
---|---|
radix |
int :
the radix used to interpret the token as an int value |
Returns | |
---|---|
boolean |
true if and only if this scanner's next token is a valid int value |
Throws | |
---|---|
IllegalStateException |
if this scanner is closed |
boolean hasNextLine ()
Returns true if there is another line in the input of this scanner. This method may block while waiting for input. The scanner does not advance past any input.
Returns | |
---|---|
boolean |
true if and only if this scanner has another line of input |
Throws | |
---|---|
IllegalStateException |
if this scanner is closed |
boolean hasNextLong ()
Returns true if the next token in this scanner's input can be
interpreted as a long value in the default radix using the
nextLong()
method. The scanner does not advance past any input.
Returns | |
---|---|
boolean |
true if and only if this scanner's next token is a valid long value |
Throws | |
---|---|
IllegalStateException |
if this scanner is closed |
boolean hasNextLong (int radix)
Returns true if the next token in this scanner's input can be
interpreted as a long value in the specified radix using the
nextLong()
method. The scanner does not advance past any input.
Parameters | |
---|---|
radix |
int :
the radix used to interpret the token as a long value |
Returns | |
---|---|
boolean |
true if and only if this scanner's next token is a valid long value |
Throws | |
---|---|
IllegalStateException |
if this scanner is closed |
boolean hasNextShort ()
Returns true if the next token in this scanner's input can be
interpreted as a short value in the default radix using the
nextShort()
method. The scanner does not advance past any input.
Returns | |
---|---|
boolean |
true if and only if this scanner's next token is a valid short value in the default radix |
Throws | |
---|---|
IllegalStateException |
if this scanner is closed |
boolean hasNextShort (int radix)
Returns true if the next token in this scanner's input can be
interpreted as a short value in the specified radix using the
nextShort()
method. The scanner does not advance past any input.
Parameters | |
---|---|
radix |
int :
the radix used to interpret the token as a short value |
Returns | |
---|---|
boolean |
true if and only if this scanner's next token is a valid short value in the specified radix |
Throws | |
---|---|
IllegalStateException |
if this scanner is closed |
IOException ioException ()
Returns the IOException
last thrown by this
Scanner
's underlying Readable
. This method
returns null
if no such exception exists.
Returns | |
---|---|
IOException |
the last exception thrown by this scanner's readable |
Locale locale ()
Returns this scanner's locale.
A scanner's locale affects many elements of its default primitive matching regular expressions; see localized numbers above.
Returns | |
---|---|
Locale |
this scanner's locale |
MatchResult match ()
Returns the match result of the last scanning operation performed
by this scanner. This method throws IllegalStateException
if no match has been performed, or if the last match was
not successful.
The various next
methods of Scanner
make a match result available if they complete without throwing an
exception. For instance, after an invocation of the nextInt()
method that returned an int, this method returns a
MatchResult
for the search of the
Integer regular expression
defined above. Similarly the findInLine(String)
,
findWithinHorizon(String, int)
, and skip(String)
methods will make a
match available if they succeed.
Returns | |
---|---|
MatchResult |
a match result for the last match operation |
Throws | |
---|---|
IllegalStateException |
If no match result is available |
String next (Pattern pattern)
Returns the next token if it matches the specified pattern. This
method may block while waiting for input to scan, even if a previous
invocation of hasNext(Pattern)
returned true
.
If the match is successful, the scanner advances past the input that
matched the pattern.
Parameters | |
---|---|
pattern |
Pattern :
the pattern to scan for |
Returns | |
---|---|
String |
the next token |
Throws | |
---|---|
NoSuchElementException |
if no more tokens are available |
IllegalStateException |
if this scanner is closed |
String next ()
Finds and returns the next complete token from this scanner.
A complete token is preceded and followed by input that matches
the delimiter pattern. This method may block while waiting for input
to scan, even if a previous invocation of hasNext()
returned
true
.
Returns | |
---|---|
String |
the next token |
Throws | |
---|---|
NoSuchElementException |
if no more tokens are available |
IllegalStateException |
if this scanner is closed |
See also:
String next (String pattern)
Returns the next token if it matches the pattern constructed from the specified string. If the match is successful, the scanner advances past the input that matched the pattern.
An invocation of this method of the form next(pattern) behaves in exactly the same way as the invocation next(Pattern.compile(pattern)).
Parameters | |
---|---|
pattern |
String :
a string specifying the pattern to scan |
Returns | |
---|---|
String |
the next token |
Throws | |
---|---|
NoSuchElementException |
if no such tokens are available |
IllegalStateException |
if this scanner is closed |
BigDecimal nextBigDecimal ()
Scans the next token of the input as a BigDecimal
.
If the next token matches the Decimal regular expression defined
above then the token is converted into a BigDecimal value as if
by removing all group separators, mapping non-ASCII digits into ASCII
digits via the Character.digit
, and passing the
resulting string to the BigDecimal(String)
constructor.
Returns | |
---|---|
BigDecimal |
the BigDecimal scanned from the input |
Throws | |
---|---|
InputMismatchException |
if the next token does not match the Decimal regular expression, or is out of range |
NoSuchElementException |
if the input is exhausted |
IllegalStateException |
if this scanner is closed |
BigInteger nextBigInteger ()
Scans the next token of the input as a BigInteger
.
An invocation of this method of the form
nextBigInteger() behaves in exactly the same way as the
invocation nextBigInteger(radix), where radix
is the default radix of this scanner.
Returns | |
---|---|
BigInteger |
the BigInteger scanned from the input |
Throws | |
---|---|
InputMismatchException |
if the next token does not match the Integer regular expression, or is out of range |
NoSuchElementException |
if the input is exhausted |
IllegalStateException |
if this scanner is closed |
BigInteger nextBigInteger (int radix)
Scans the next token of the input as a BigInteger
.
If the next token matches the Integer regular expression defined
above then the token is converted into a BigInteger value as if
by removing all group separators, mapping non-ASCII digits into ASCII
digits via the Character.digit
, and passing the
resulting string to the BigInteger(String, int)
constructor with the specified radix.
Parameters | |
---|---|
radix |
int :
the radix used to interpret the token |
Returns | |
---|---|
BigInteger |
the BigInteger scanned from the input |
Throws | |
---|---|
InputMismatchException |
if the next token does not match the Integer regular expression, or is out of range |
NoSuchElementException |
if the input is exhausted |
IllegalStateException |
if this scanner is closed |
boolean nextBoolean ()
Scans the next token of the input into a boolean value and returns
that value. This method will throw InputMismatchException
if the next token cannot be translated into a valid boolean value.
If the match is successful, the scanner advances past the input that
matched.
Returns | |
---|---|
boolean |
the boolean scanned from the input |
Throws | |
---|---|
InputMismatchException |
if the next token is not a valid boolean |
NoSuchElementException |
if input is exhausted |
IllegalStateException |
if this scanner is closed |
byte nextByte (int radix)
Scans the next token of the input as a byte.
This method will throw InputMismatchException
if the next token cannot be translated into a valid byte value as
described below. If the translation is successful, the scanner advances
past the input that matched.
If the next token matches the Integer regular expression defined
above then the token is converted into a byte value as if by
removing all locale specific prefixes, group separators, and locale
specific suffixes, then mapping non-ASCII digits into ASCII
digits via Character.digit
, prepending a
negative sign (-) if the locale specific negative prefixes and suffixes
were present, and passing the resulting string to
Byte.parseByte
with the
specified radix.
Parameters | |
---|---|
radix |
int :
the radix used to interpret the token as a byte value |
Returns | |
---|---|
byte |
the byte scanned from the input |
Throws | |
---|---|
InputMismatchException |
if the next token does not match the Integer regular expression, or is out of range |
NoSuchElementException |
if input is exhausted |
IllegalStateException |
if this scanner is closed |
byte nextByte ()
Scans the next token of the input as a byte.
An invocation of this method of the form
nextByte() behaves in exactly the same way as the
invocation nextByte(radix), where radix
is the default radix of this scanner.
Returns | |
---|---|
byte |
the byte scanned from the input |
Throws | |
---|---|
InputMismatchException |
if the next token does not match the Integer regular expression, or is out of range |
NoSuchElementException |
if input is exhausted |
IllegalStateException |
if this scanner is closed |
double nextDouble ()
Scans the next token of the input as a double.
This method will throw InputMismatchException
if the next token cannot be translated into a valid double value.
If the translation is successful, the scanner advances past the input
that matched.
If the next token matches the Float regular expression defined above
then the token is converted into a double value as if by
removing all locale specific prefixes, group separators, and locale
specific suffixes, then mapping non-ASCII digits into ASCII
digits via Character.digit
, prepending a
negative sign (-) if the locale specific negative prefixes and suffixes
were present, and passing the resulting string to
Double.parseDouble
. If the token matches
the localized NaN or infinity strings, then either "Nan" or "Infinity"
is passed to Double.parseDouble
as
appropriate.
Returns | |
---|---|
double |
the double scanned from the input |
Throws | |
---|---|
InputMismatchException |
if the next token does not match the Float regular expression, or is out of range |
NoSuchElementException |
if the input is exhausted |
IllegalStateException |
if this scanner is closed |
float nextFloat ()
Scans the next token of the input as a float.
This method will throw InputMismatchException
if the next token cannot be translated into a valid float value as
described below. If the translation is successful, the scanner advances
past the input that matched.
If the next token matches the Float regular expression defined above
then the token is converted into a float value as if by
removing all locale specific prefixes, group separators, and locale
specific suffixes, then mapping non-ASCII digits into ASCII
digits via Character.digit
, prepending a
negative sign (-) if the locale specific negative prefixes and suffixes
were present, and passing the resulting string to
Float.parseFloat
. If the token matches
the localized NaN or infinity strings, then either "Nan" or "Infinity"
is passed to Float.parseFloat
as
appropriate.
Returns | |
---|---|
float |
the float scanned from the input |
Throws | |
---|---|
InputMismatchException |
if the next token does not match the Float regular expression, or is out of range |
NoSuchElementException |
if input is exhausted |
IllegalStateException |
if this scanner is closed |
int nextInt ()
Scans the next token of the input as an int.
An invocation of this method of the form
nextInt() behaves in exactly the same way as the
invocation nextInt(radix), where radix
is the default radix of this scanner.
Returns | |
---|---|
int |
the int scanned from the input |
Throws | |
---|---|
InputMismatchException |
if the next token does not match the Integer regular expression, or is out of range |
NoSuchElementException |
if input is exhausted |
IllegalStateException |
if this scanner is closed |
int nextInt (int radix)
Scans the next token of the input as an int.
This method will throw InputMismatchException
if the next token cannot be translated into a valid int value as
described below. If the translation is successful, the scanner advances
past the input that matched.
If the next token matches the Integer regular expression defined
above then the token is converted into an int value as if by
removing all locale specific prefixes, group separators, and locale
specific suffixes, then mapping non-ASCII digits into ASCII
digits via Character.digit
, prepending a
negative sign (-) if the locale specific negative prefixes and suffixes
were present, and passing the resulting string to
Integer.parseInt
with the
specified radix.
Parameters | |
---|---|
radix |
int :
the radix used to interpret the token as an int value |
Returns | |
---|---|
int |
the int scanned from the input |
Throws | |
---|---|
InputMismatchException |
if the next token does not match the Integer regular expression, or is out of range |
NoSuchElementException |
if input is exhausted |
IllegalStateException |
if this scanner is closed |
String nextLine ()
Advances this scanner past the current line and returns the input that was skipped. This method returns the rest of the current line, excluding any line separator at the end. The position is set to the beginning of the next line.
Since this method continues to search through the input looking for a line separator, it may buffer all of the input searching for the line to skip if no line separators are present.
Returns | |
---|---|
String |
the line that was skipped |
Throws | |
---|---|
NoSuchElementException |
if no line was found |
IllegalStateException |
if this scanner is closed |
long nextLong ()
Scans the next token of the input as a long.
An invocation of this method of the form
nextLong() behaves in exactly the same way as the
invocation nextLong(radix), where radix
is the default radix of this scanner.
Returns | |
---|---|
long |
the long scanned from the input |
Throws | |
---|---|
InputMismatchException |
if the next token does not match the Integer regular expression, or is out of range |
NoSuchElementException |
if input is exhausted |
IllegalStateException |
if this scanner is closed |
long nextLong (int radix)
Scans the next token of the input as a long.
This method will throw InputMismatchException
if the next token cannot be translated into a valid long value as
described below. If the translation is successful, the scanner advances
past the input that matched.
If the next token matches the Integer regular expression defined
above then the token is converted into a long value as if by
removing all locale specific prefixes, group separators, and locale
specific suffixes, then mapping non-ASCII digits into ASCII
digits via Character.digit
, prepending a
negative sign (-) if the locale specific negative prefixes and suffixes
were present, and passing the resulting string to
Long.parseLong
with the
specified radix.
Parameters | |
---|---|
radix |
int :
the radix used to interpret the token as an int value |
Returns | |
---|---|
long |
the long scanned from the input |
Throws | |
---|---|
InputMismatchException |
if the next token does not match the Integer regular expression, or is out of range |
NoSuchElementException |
if input is exhausted |
IllegalStateException |
if this scanner is closed |
short nextShort (int radix)
Scans the next token of the input as a short.
This method will throw InputMismatchException
if the next token cannot be translated into a valid short value as
described below. If the translation is successful, the scanner advances
past the input that matched.
If the next token matches the Integer regular expression defined
above then the token is converted into a short value as if by
removing all locale specific prefixes, group separators, and locale
specific suffixes, then mapping non-ASCII digits into ASCII
digits via Character.digit
, prepending a
negative sign (-) if the locale specific negative prefixes and suffixes
were present, and passing the resulting string to
Short.parseShort
with the
specified radix.
Parameters | |
---|---|
radix |
int :
the radix used to interpret the token as a short value |
Returns | |
---|---|
short |
the short scanned from the input |
Throws | |
---|---|
InputMismatchException |
if the next token does not match the Integer regular expression, or is out of range |
NoSuchElementException |
if input is exhausted |
IllegalStateException |
if this scanner is closed |
short nextShort ()
Scans the next token of the input as a short.
An invocation of this method of the form
nextShort() behaves in exactly the same way as the
invocation nextShort(radix), where radix
is the default radix of this scanner.
Returns | |
---|---|
short |
the short scanned from the input |
Throws | |
---|---|
InputMismatchException |
if the next token does not match the Integer regular expression, or is out of range |
NoSuchElementException |
if input is exhausted |
IllegalStateException |
if this scanner is closed |
int radix ()
Returns this scanner's default radix.
A scanner's radix affects elements of its default number matching regular expressions; see localized numbers above.
Returns | |
---|---|
int |
the default radix of this scanner |
void remove ()
The remove operation is not supported by this implementation of
Iterator
.
Throws | |
---|---|
UnsupportedOperationException |
if this method is invoked. |
See also:
Scanner reset ()
Resets this scanner.
Resetting a scanner discards all of its explicit state
information which may have been changed by invocations of useDelimiter(String)
, useLocale(Locale)
, or useRadix(int)
.
An invocation of this method of the form scanner.reset() behaves in exactly the same way as the invocation
scanner.useDelimiter("\\p{javaWhitespace}+") .useLocale(Locale.getDefault()) .useRadix(10);
Returns | |
---|---|
Scanner |
this scanner |
Scanner skip (String pattern)
Skips input that matches a pattern constructed from the specified string.
An invocation of this method of the form skip(pattern) behaves in exactly the same way as the invocation skip(Pattern.compile(pattern)).
Parameters | |
---|---|
pattern |
String :
a string specifying the pattern to skip over |
Returns | |
---|---|
Scanner |
this scanner |
Throws | |
---|---|
IllegalStateException |
if this scanner is closed |
Scanner skip (Pattern pattern)
Skips input that matches the specified pattern, ignoring delimiters. This method will skip input if an anchored match of the specified pattern succeeds.
If a match to the specified pattern is not found at the current position, then no input is skipped and a NoSuchElementException is thrown.
Since this method seeks to match the specified pattern starting at the scanner's current position, patterns that can match a lot of input (".*", for example) may cause the scanner to buffer a large amount of input.
Note that it is possible to skip something without risking a
NoSuchElementException
by using a pattern that can
match nothing, e.g., sc.skip("[ \t]*")
.
Parameters | |
---|---|
pattern |
Pattern :
a string specifying the pattern to skip over |
Returns | |
---|---|
Scanner |
this scanner |
Throws | |
---|---|
NoSuchElementException |
if the specified pattern is not found |
IllegalStateException |
if this scanner is closed |
String toString ()
Returns the string representation of this Scanner
. The
string representation of a Scanner
contains information
that may be useful for debugging. The exact format is unspecified.
Returns | |
---|---|
String |
The string representation of this scanner |
Scanner useDelimiter (Pattern pattern)
Sets this scanner's delimiting pattern to the specified pattern.
Parameters | |
---|---|
pattern |
Pattern :
A delimiting pattern |
Returns | |
---|---|
Scanner |
this scanner |
Scanner useDelimiter (String pattern)
Sets this scanner's delimiting pattern to a pattern constructed from
the specified String
.
An invocation of this method of the form useDelimiter(pattern) behaves in exactly the same way as the invocation useDelimiter(Pattern.compile(pattern)).
Invoking the reset()
method will set the scanner's delimiter
to the default.
Parameters | |
---|---|
pattern |
String :
A string specifying a delimiting pattern |
Returns | |
---|---|
Scanner |
this scanner |
Scanner useLocale (Locale locale)
Sets this scanner's locale to the specified locale.
A scanner's locale affects many elements of its default primitive matching regular expressions; see localized numbers above.
Invoking the reset()
method will set the scanner's locale to
the initial locale.
Parameters | |
---|---|
locale |
Locale :
A string specifying the locale to use |
Returns | |
---|---|
Scanner |
this scanner |
Scanner useRadix (int radix)
Sets this scanner's default radix to the specified radix.
A scanner's radix affects elements of its default number matching regular expressions; see localized numbers above.
If the radix is less than Character.MIN_RADIX
or greater than Character.MAX_RADIX
, then an
IllegalArgumentException
is thrown.
Invoking the reset()
method will set the scanner's radix to
10
.
Parameters | |
---|---|
radix |
int :
The radix to use when scanning numbers |
Returns | |
---|---|
Scanner |
this scanner |
Throws | |
---|---|
IllegalArgumentException |
if radix is out of range |