Closeable
, AutoCloseable
, Iterator<String>
public final class Scanner extends Object implements Iterator<String>, Closeable
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
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 tokens()
method
may also block waiting for input.
The findInLine()
,
findWithinHorizon()
,
skip()
, and findAll()
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()
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 useRadix(int)
method. The
reset()
method will reset the value of the scanner's radix to
10
regardless of whether it was previously changed.
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 Locale.getDefault(Locale.Category.FORMAT)
method; it may be changed via the useLocale()
method. The reset()
method will reset the value of the
scanner's locale to the initial locale regardless of whether it was
previously changed.
The localized formats are defined in terms of the following parameters,
which for a particular locale are taken from that locale's 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()
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).
Character.isDigit
(c)
returns true
[1-
Rmax] |
NonASCIIDigit
[0-
Rmax] |
NonASCIIDigit
(
Non0Digit
Digit?
Digit?
(
LocalGroupSeparator
Digit
Digit
Digit )+ )
( (
Digit+ )
|
GroupedNumeral )
( [-+]? (
Numeral
) )
|
LocalPositivePrefix Numeral
LocalPositiveSuffix
|
LocalNegativePrefix Numeral
LocalNegativeSuffix
|
Numeral
LocalDecimalSeparator
Digit*
|
LocalDecimalSeparator
Digit+
( [eE] [+-]?
Digit+ )
( [-+]?
DecimalNumeral
Exponent? )
|
LocalPositivePrefix
DecimalNumeral
LocalPositiveSuffix
Exponent?
|
LocalNegativePrefix
DecimalNumeral
LocalNegativeSuffix
Exponent?
[-+]? 0[xX][0-9a-fA-F]*\.[0-9a-fA-F]+
([pP][-+]?[0-9]+)?
NaN
|
LocalNan
| Infinity
|
LocalInfinity
( [-+]?
NonNumber )
|
LocalPositivePrefix
NonNumber
LocalPositiveSuffix
|
LocalNegativePrefix
NonNumber
LocalNegativeSuffix
|
HexFloat
|
SignedNonNumber
Whitespace is not significant in the above regular expressions.
Constructor | Description |
---|---|
Scanner(File source) |
Constructs a new
Scanner that produces values scanned
from the specified file. |
Scanner(File source,
String charsetName) |
Constructs a new
Scanner that produces values scanned
from the specified file. |
Scanner(InputStream source) |
Constructs a new
Scanner that produces values scanned
from the specified input stream. |
Scanner(InputStream source,
String charsetName) |
Constructs a new
Scanner that produces values scanned
from the specified input stream. |
Scanner(Readable source) |
Constructs a new
Scanner that produces values scanned
from the specified source. |
Scanner(String source) |
Constructs a new
Scanner that produces values scanned
from the specified string. |
Scanner(ReadableByteChannel source) |
Constructs a new
Scanner that produces values scanned
from the specified channel. |
Scanner(ReadableByteChannel source,
String charsetName) |
Constructs a new
Scanner that produces values scanned
from the specified channel. |
Scanner(Path source) |
Constructs a new
Scanner that produces values scanned
from the specified file. |
Scanner(Path source,
String charsetName) |
Constructs a new
Scanner that produces values scanned
from the specified file. |
Modifier and Type | Method | Description |
---|---|---|
void |
close() |
Closes this scanner.
|
Pattern |
delimiter() |
Returns the
Pattern this Scanner is currently
using to match delimiters. |
Stream<MatchResult> |
findAll(String patString) |
Returns a stream of match results that match the provided pattern string.
|
Stream<MatchResult> |
findAll(Pattern pattern) |
Returns a stream of match results from this scanner.
|
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(String pattern,
int horizon) |
Attempts to find the next occurrence of a pattern constructed from the
specified string, ignoring delimiters.
|
String |
findWithinHorizon(Pattern pattern,
int horizon) |
Attempts to find the next occurrence of the specified pattern.
|
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
BigDecimal using the
nextBigDecimal() method. |
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. |
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. |
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
nextByte() method. |
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. |
boolean |
hasNextDouble() |
Returns true if the next token in this scanner's input can be
interpreted as a double value using the
nextDouble()
method. |
boolean |
hasNextFloat() |
Returns true if the next token in this scanner's input can be
interpreted as a float value using the
nextFloat()
method. |
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. |
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. |
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
nextLong() method. |
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. |
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. |
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. |
IOException |
ioException() |
Returns the
IOException last thrown by this
Scanner 's underlying Readable . |
Locale |
locale() |
Returns this scanner's locale.
|
MatchResult |
match() |
Returns the match result of the last scanning operation performed
by this scanner.
|
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.
|
String |
next(Pattern pattern) |
Returns the next token if it matches the specified pattern.
|
BigDecimal |
nextBigDecimal() |
Scans the next token of the input as a
BigDecimal . |
BigInteger |
nextBigInteger() |
Scans the next token of the input as a
BigInteger . |
BigInteger |
nextBigInteger(int radix) |
Scans the next token of the input as a
BigInteger . |
boolean |
nextBoolean() |
Scans the next token of the input into a boolean value and returns
that value.
|
byte |
nextByte() |
Scans the next token of the input as a
byte . |
byte |
nextByte(int radix) |
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() |
Scans the next token of the input as a
short . |
short |
nextShort(int radix) |
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
Iterator . |
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.
|
Stream<String> |
tokens() |
Returns a stream of delimiter-separated tokens from this scanner.
|
String |
toString() |
Returns the string representation of this
Scanner . |
Scanner |
useDelimiter(String pattern) |
Sets this scanner's delimiting pattern to a pattern constructed from
the specified
String . |
Scanner |
useDelimiter(Pattern pattern) |
Sets this scanner's delimiting pattern to the specified pattern.
|
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.
|
forEachRemaining
public Scanner(Readable source)
Scanner
that produces values scanned
from the specified source.source
- A character source implementing the Readable
interfacepublic Scanner(InputStream source)
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.source
- An input stream to be scannedpublic Scanner(InputStream source, String charsetName)
Scanner
that produces values scanned
from the specified input stream. Bytes from the stream are converted
into characters using the specified charset.source
- An input stream to be scannedcharsetName
- The encoding type used to convert bytes from the
stream into characters to be scannedIllegalArgumentException
- if the specified character set
does not existpublic Scanner(File source) throws FileNotFoundException
Scanner
that produces values scanned
from the specified file. Bytes from the file are converted into
characters using the underlying platform's
default charset.source
- A file to be scannedFileNotFoundException
- if source is not foundpublic Scanner(File source, String charsetName) throws FileNotFoundException
Scanner
that produces values scanned
from the specified file. Bytes from the file are converted into
characters using the specified charset.source
- A file to be scannedcharsetName
- The encoding type used to convert bytes from the file
into characters to be scannedFileNotFoundException
- if source is not foundIllegalArgumentException
- if the specified encoding is
not foundpublic Scanner(Path source) throws IOException
Scanner
that produces values scanned
from the specified file. Bytes from the file are converted into
characters using the underlying platform's
default charset.source
- the path to the file to be scannedIOException
- if an I/O error occurs opening sourcepublic Scanner(Path source, String charsetName) throws IOException
Scanner
that produces values scanned
from the specified file. Bytes from the file are converted into
characters using the specified charset.source
- the path to the file to be scannedcharsetName
- The encoding type used to convert bytes from the file
into characters to be scannedIOException
- if an I/O error occurs opening sourceIllegalArgumentException
- if the specified encoding is not foundpublic Scanner(String source)
Scanner
that produces values scanned
from the specified string.source
- A string to scanpublic Scanner(ReadableByteChannel source)
Scanner
that produces values scanned
from the specified channel. Bytes from the source are converted into
characters using the underlying platform's
default charset.source
- A channel to scanpublic Scanner(ReadableByteChannel source, String charsetName)
Scanner
that produces values scanned
from the specified channel. Bytes from the source are converted into
characters using the specified charset.source
- A channel to scancharsetName
- The encoding type used to convert bytes from the
channel into characters to be scannedIllegalArgumentException
- if the specified character set
does not existpublic void close()
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
.
close
in interface AutoCloseable
close
in interface Closeable
public IOException ioException()
IOException
last thrown by this
Scanner
's underlying Readable
. This method
returns null
if no such exception exists.public Pattern delimiter()
Pattern
this Scanner
is currently
using to match delimiters.public Scanner useDelimiter(Pattern pattern)
pattern
- A delimiting patternpublic Scanner useDelimiter(String pattern)
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.
pattern
- A string specifying a delimiting patternpublic Locale locale()
A scanner's locale affects many elements of its default primitive matching regular expressions; see localized numbers above.
public Scanner useLocale(Locale 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.
locale
- A string specifying the locale to usepublic int radix()
A scanner's radix affects elements of its default number matching regular expressions; see localized numbers above.
public Scanner useRadix(int 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
.
radix
- The radix to use when scanning numbersIllegalArgumentException
- if radix is out of rangepublic MatchResult match()
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()
,
findWithinHorizon()
, and skip()
methods will make a match available if they succeed.
IllegalStateException
- If no match result is availablepublic 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.
public boolean hasNext()
hasNext
in interface Iterator<String>
IllegalStateException
- if this scanner is closedIterator
public String next()
hasNext()
returned
true
.next
in interface Iterator<String>
NoSuchElementException
- if no more tokens are availableIllegalStateException
- if this scanner is closedIterator
public void remove()
Iterator
.remove
in interface Iterator<String>
UnsupportedOperationException
- if this method is invoked.Iterator
public boolean hasNext(String pattern)
An invocation of this method of the form hasNext(pattern)
behaves in exactly the same way as the invocation
hasNext(Pattern.compile(pattern))
.
pattern
- a string specifying the pattern to scanIllegalStateException
- if this scanner is closedpublic String next(String pattern)
An invocation of this method of the form next(pattern)
behaves in exactly the same way as the invocation
next(Pattern.compile(pattern))
.
pattern
- a string specifying the pattern to scanNoSuchElementException
- if no such tokens are availableIllegalStateException
- if this scanner is closedpublic boolean hasNext(Pattern pattern)
pattern
- the pattern to scan forIllegalStateException
- if this scanner is closedpublic String next(Pattern pattern)
hasNext(Pattern)
returned true
.
If the match is successful, the scanner advances past the input that
matched the pattern.pattern
- the pattern to scan forNoSuchElementException
- if no more tokens are availableIllegalStateException
- if this scanner is closedpublic boolean hasNextLine()
IllegalStateException
- if this scanner is closedpublic String nextLine()
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.
NoSuchElementException
- if no line was foundIllegalStateException
- if this scanner is closedpublic String findInLine(String pattern)
An invocation of this method of the form findInLine(pattern)
behaves in exactly the same way as the invocation
findInLine(Pattern.compile(pattern))
.
pattern
- a string specifying the pattern to search forIllegalStateException
- if this scanner is closedpublic String findInLine(Pattern pattern)
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.
pattern
- the pattern to scan forIllegalStateException
- if this scanner is closedpublic String findWithinHorizon(String pattern, int horizon)
An invocation of this method of the form
findWithinHorizon(pattern)
behaves in exactly the same way as
the invocation
findWithinHorizon(Pattern.compile(pattern), horizon)
.
pattern
- a string specifying the pattern to search forhorizon
- the search horizonIllegalStateException
- if this scanner is closedIllegalArgumentException
- if horizon is negativepublic String findWithinHorizon(Pattern pattern, int horizon)
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 Matcher.useTransparentBounds(boolean)
and Matcher.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.
pattern
- the pattern to scan forhorizon
- the search horizonIllegalStateException
- if this scanner is closedIllegalArgumentException
- if horizon is negativepublic Scanner skip(Pattern pattern)
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]*")
.
pattern
- a string specifying the pattern to skip overNoSuchElementException
- if the specified pattern is not foundIllegalStateException
- if this scanner is closedpublic Scanner skip(String pattern)
An invocation of this method of the form skip(pattern)
behaves in exactly the same way as the invocation
skip(Pattern.compile(pattern))
.
pattern
- a string specifying the pattern to skip overIllegalStateException
- if this scanner is closedpublic boolean hasNextBoolean()
IllegalStateException
- if this scanner is closedpublic boolean nextBoolean()
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.InputMismatchException
- if the next token is not a valid booleanNoSuchElementException
- if input is exhaustedIllegalStateException
- if this scanner is closedpublic boolean hasNextByte()
nextByte()
method. The scanner does not advance past any input.IllegalStateException
- if this scanner is closedpublic boolean hasNextByte(int radix)
nextByte()
method. The scanner does not advance past any input.
If the radix is less than Character.MIN_RADIX
or greater than Character.MAX_RADIX
, then an
IllegalArgumentException
is thrown.
radix
- the radix used to interpret the token as a byte valueIllegalStateException
- if this scanner is closedIllegalArgumentException
- if the radix is out of rangepublic byte nextByte()
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.
byte
scanned from the inputInputMismatchException
- if the next token does not match the Integer
regular expression, or is out of rangeNoSuchElementException
- if input is exhaustedIllegalStateException
- if this scanner is closedpublic byte nextByte(int radix)
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.
If the radix is less than Character.MIN_RADIX
or greater than Character.MAX_RADIX
, then an
IllegalArgumentException
is thrown.
radix
- the radix used to interpret the token as a byte valuebyte
scanned from the inputInputMismatchException
- if the next token does not match the Integer
regular expression, or is out of rangeNoSuchElementException
- if input is exhaustedIllegalStateException
- if this scanner is closedIllegalArgumentException
- if the radix is out of rangepublic boolean hasNextShort()
nextShort()
method. The scanner does not advance past any input.IllegalStateException
- if this scanner is closedpublic boolean hasNextShort(int radix)
nextShort()
method. The scanner does not advance past any input.
If the radix is less than Character.MIN_RADIX
or greater than Character.MAX_RADIX
, then an
IllegalArgumentException
is thrown.
radix
- the radix used to interpret the token as a short valueIllegalStateException
- if this scanner is closedIllegalArgumentException
- if the radix is out of rangepublic short nextShort()
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.
short
scanned from the inputInputMismatchException
- if the next token does not match the Integer
regular expression, or is out of rangeNoSuchElementException
- if input is exhaustedIllegalStateException
- if this scanner is closedpublic short nextShort(int radix)
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.
If the radix is less than Character.MIN_RADIX
or greater than Character.MAX_RADIX
, then an
IllegalArgumentException
is thrown.
radix
- the radix used to interpret the token as a short valueshort
scanned from the inputInputMismatchException
- if the next token does not match the Integer
regular expression, or is out of rangeNoSuchElementException
- if input is exhaustedIllegalStateException
- if this scanner is closedIllegalArgumentException
- if the radix is out of rangepublic boolean hasNextInt()
nextInt()
method. The scanner does not advance past any input.IllegalStateException
- if this scanner is closedpublic boolean hasNextInt(int radix)
nextInt()
method. The scanner does not advance past any input.
If the radix is less than Character.MIN_RADIX
or greater than Character.MAX_RADIX
, then an
IllegalArgumentException
is thrown.
radix
- the radix used to interpret the token as an int valueIllegalStateException
- if this scanner is closedIllegalArgumentException
- if the radix is out of rangepublic int nextInt()
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.
int
scanned from the inputInputMismatchException
- if the next token does not match the Integer
regular expression, or is out of rangeNoSuchElementException
- if input is exhaustedIllegalStateException
- if this scanner is closedpublic int nextInt(int radix)
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.
If the radix is less than Character.MIN_RADIX
or greater than Character.MAX_RADIX
, then an
IllegalArgumentException
is thrown.
radix
- the radix used to interpret the token as an int valueint
scanned from the inputInputMismatchException
- if the next token does not match the Integer
regular expression, or is out of rangeNoSuchElementException
- if input is exhaustedIllegalStateException
- if this scanner is closedIllegalArgumentException
- if the radix is out of rangepublic boolean hasNextLong()
nextLong()
method. The scanner does not advance past any input.IllegalStateException
- if this scanner is closedpublic boolean hasNextLong(int radix)
nextLong()
method. The scanner does not advance past any input.
If the radix is less than Character.MIN_RADIX
or greater than Character.MAX_RADIX
, then an
IllegalArgumentException
is thrown.
radix
- the radix used to interpret the token as a long valueIllegalStateException
- if this scanner is closedIllegalArgumentException
- if the radix is out of rangepublic long nextLong()
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.
long
scanned from the inputInputMismatchException
- if the next token does not match the Integer
regular expression, or is out of rangeNoSuchElementException
- if input is exhaustedIllegalStateException
- if this scanner is closedpublic long nextLong(int radix)
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.
If the radix is less than Character.MIN_RADIX
or greater than Character.MAX_RADIX
, then an
IllegalArgumentException
is thrown.
radix
- the radix used to interpret the token as an int valuelong
scanned from the inputInputMismatchException
- if the next token does not match the Integer
regular expression, or is out of rangeNoSuchElementException
- if input is exhaustedIllegalStateException
- if this scanner is closedIllegalArgumentException
- if the radix is out of rangepublic boolean hasNextFloat()
nextFloat()
method. The scanner does not advance past any input.IllegalStateException
- if this scanner is closedpublic float nextFloat()
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.
float
scanned from the inputInputMismatchException
- if the next token does not match the Float
regular expression, or is out of rangeNoSuchElementException
- if input is exhaustedIllegalStateException
- if this scanner is closedpublic boolean hasNextDouble()
nextDouble()
method. The scanner does not advance past any input.IllegalStateException
- if this scanner is closedpublic double nextDouble()
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.
double
scanned from the inputInputMismatchException
- if the next token does not match the Float
regular expression, or is out of rangeNoSuchElementException
- if the input is exhaustedIllegalStateException
- if this scanner is closedpublic boolean hasNextBigInteger()
BigInteger
in the default radix using the
nextBigInteger()
method. The scanner does not advance past any
input.BigInteger
IllegalStateException
- if this scanner is closedpublic boolean hasNextBigInteger(int radix)
BigInteger
in the specified radix using
the nextBigInteger()
method. The scanner does not advance past
any input.
If the radix is less than Character.MIN_RADIX
or greater than Character.MAX_RADIX
, then an
IllegalArgumentException
is thrown.
radix
- the radix used to interpret the token as an integerBigInteger
IllegalStateException
- if this scanner is closedIllegalArgumentException
- if the radix is out of rangepublic BigInteger nextBigInteger()
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.
BigInteger
scanned from the inputInputMismatchException
- if the next token does not match the Integer
regular expression, or is out of rangeNoSuchElementException
- if the input is exhaustedIllegalStateException
- if this scanner is closedpublic BigInteger nextBigInteger(int radix)
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.
If the radix is less than Character.MIN_RADIX
or greater than Character.MAX_RADIX
, then an
IllegalArgumentException
is thrown.
radix
- the radix used to interpret the tokenBigInteger
scanned from the inputInputMismatchException
- if the next token does not match the Integer
regular expression, or is out of rangeNoSuchElementException
- if the input is exhaustedIllegalStateException
- if this scanner is closedIllegalArgumentException
- if the radix is out of rangepublic boolean hasNextBigDecimal()
BigDecimal
using the
nextBigDecimal()
method. The scanner does not advance past any
input.BigDecimal
IllegalStateException
- if this scanner is closedpublic BigDecimal nextBigDecimal()
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.
BigDecimal
scanned from the inputInputMismatchException
- if the next token does not match the Decimal
regular expression, or is out of rangeNoSuchElementException
- if the input is exhaustedIllegalStateException
- if this scanner is closedpublic Scanner reset()
Resetting a scanner discards all of its explicit state
information which may have been changed by invocations of
useDelimiter()
,
useLocale()
, or
useRadix()
.
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(Locale.Category.FORMAT)) .useRadix(10);
public Stream<String> tokens()
next()
method
repeatedly until the hasNext()
method returns false.
The resulting stream is sequential and ordered. All stream elements are non-null.
Scanning starts upon initiation of the terminal stream operation, using the
current state of this scanner. Subsequent calls to any methods on this scanner
other than close()
and ioException()
may return undefined results
or may cause undefined effects on the returned stream. The returned stream's source
Spliterator
is fail-fast and will, on a best-effort basis, throw a
ConcurrentModificationException
if any such calls are detected
during stream pipeline execution.
After stream pipeline execution completes, this scanner is left in an indeterminate state and cannot be reused.
If this scanner contains a resource that must be released, this scanner
should be closed, either by calling its close()
method, or by
closing the returned stream. Closing the stream will close the underlying scanner.
IllegalStateException
is thrown if the scanner has been closed when this
method is called, or if this scanner is closed during stream pipeline execution.
This method might block waiting for more input.
List<String> result = new Scanner("abc,def,,ghi")
.useDelimiter(",")
.tokens()
.collect(Collectors.toList());
The resulting list would contain "abc"
, "def"
,
the empty string, and "ghi"
.
IllegalStateException
- if this scanner is closedpublic Stream<MatchResult> findAll(Pattern pattern)
findWithinHorizon(pattern, 0)
and then match()
successively as long as findWithinHorizon()
finds matches.
The resulting stream is sequential and ordered. All stream elements are non-null.
Scanning starts upon initiation of the terminal stream operation, using the
current state of this scanner. Subsequent calls to any methods on this scanner
other than close()
and ioException()
may return undefined results
or may cause undefined effects on the returned stream. The returned stream's source
Spliterator
is fail-fast and will, on a best-effort basis, throw a
ConcurrentModificationException
if any such calls are detected
during stream pipeline execution.
After stream pipeline execution completes, this scanner is left in an indeterminate state and cannot be reused.
If this scanner contains a resource that must be released, this scanner
should be closed, either by calling its close()
method, or by
closing the returned stream. Closing the stream will close the underlying scanner.
IllegalStateException
is thrown if the scanner has been closed when this
method is called, or if this scanner is closed during stream pipeline execution.
As with the findWithinHorizon()
methods, this method
might block waiting for additional input, and it might buffer an unbounded amount of
input searching for a match.
try (Scanner sc = new Scanner(Paths.get("input.txt"))) {
Pattern pat = Pattern.compile("[A-Z]{7,}");
List<String> capWords = sc.findAll(pat)
.map(MatchResult::group)
.collect(Collectors.toList());
}
pattern
- the pattern to be matchedNullPointerException
- if pattern is nullIllegalStateException
- if this scanner is closedpublic Stream<MatchResult> findAll(String patString)
scanner.findAll(Pattern.compile(patString))
patString
- the pattern stringNullPointerException
- if patString is nullIllegalStateException
- if this scanner is closedPatternSyntaxException
- if the regular expression's syntax is invalidPattern
Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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DRAFT 9-internal+0-adhoc.mlchung.jdk9-jdeps