- java.lang.Object
-
- java.util.Scanner
-
- All Implemented Interfaces:
- Closeable, AutoCloseable, Iterator<String>
public final class Scanner extends Object implements Iterator<String>, Closeable
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 filemyNumbers
: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
. Thereset()
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()
andhasNext()
methods and their primitive-type companion methods (such asnextInt()
andhasNextInt()
) 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(java.lang.String)
,findWithinHorizon(java.lang.String, int)
, andskip(java.util.regex.Pattern)
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'sReadable.read(java.nio.CharBuffer)
method throws anIOException
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 theioException()
method.When a
Scanner
is closed, it will close its input source if the source implements theCloseable
interface.A
Scanner
is not safe for multithreaded use without external synchronization.Unless otherwise mentioned, passing a
null
parameter into any method of aScanner
will cause aNullPointerException
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. Thereset()
method will reset the value of the scanner's radix to10
regardless of whether it was previously changed.Localized numbers
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()
method; it may be changed via theuseLocale(java.util.Locale)
method. Thereset()
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 andDecimalFormatSymbols
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
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).
NonASCIIDigit :: = A non-ASCII character c for which Character.isDigit
(c) returns trueNon0Digit :: = [1-Rmax] | NonASCIIDigit Digit :: = [0-Rmax] | NonASCIIDigit GroupedNumeral :: = ( Non0Digit Digit? Digit? ( LocalGroupSeparator Digit Digit Digit )+ ) 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.
- Since:
- 1.5
-
-
Constructor Summary
Constructors Constructor and Description Scanner(File source)
Constructs a newScanner
that produces values scanned from the specified file.Scanner(File source, String charsetName)
Constructs a newScanner
that produces values scanned from the specified file.Scanner(InputStream source)
Constructs a newScanner
that produces values scanned from the specified input stream.Scanner(InputStream source, String charsetName)
Constructs a newScanner
that produces values scanned from the specified input stream.Scanner(Path source)
Constructs a newScanner
that produces values scanned from the specified file.Scanner(Path source, String charsetName)
Constructs a newScanner
that produces values scanned from the specified file.Scanner(Readable source)
Constructs a newScanner
that produces values scanned from the specified source.Scanner(ReadableByteChannel source)
Constructs a newScanner
that produces values scanned from the specified channel.Scanner(ReadableByteChannel source, String charsetName)
Constructs a newScanner
that produces values scanned from the specified channel.Scanner(String source)
Constructs a newScanner
that produces values scanned from the specified string.
-
Method Summary
Methods Modifier and Type Method and Description void
close()
Closes this scanner.Pattern
delimiter()
Returns thePattern
thisScanner
is currently using to match delimiters.String
findInLine(Pattern pattern)
Attempts to find the next occurrence of the specified pattern ignoring delimiters.String
findInLine(String pattern)
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.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(Pattern pattern)
Returns true if the next complete token matches the specified pattern.boolean
hasNext(String pattern)
Returns true if the next token matches the pattern constructed from the specified string.boolean
hasNextBigDecimal()
Returns true if the next token in this scanner's input can be interpreted as aBigDecimal
using thenextBigDecimal()
method.boolean
hasNextBigInteger()
Returns true if the next token in this scanner's input can be interpreted as aBigInteger
in the default radix using thenextBigInteger()
method.boolean
hasNextBigInteger(int radix)
Returns true if the next token in this scanner's input can be interpreted as aBigInteger
in the specified radix using thenextBigInteger()
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 thenextByte()
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 thenextByte()
method.boolean
hasNextDouble()
Returns true if the next token in this scanner's input can be interpreted as a double value using thenextDouble()
method.boolean
hasNextFloat()
Returns true if the next token in this scanner's input can be interpreted as a float value using thenextFloat()
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 thenextInt()
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 thenextInt()
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 thenextLong()
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 thenextLong()
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 thenextShort()
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 thenextShort()
method.IOException
ioException()
Returns theIOException
last thrown by thisScanner
's underlyingReadable
.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(Pattern pattern)
Returns the next token if it matches the specified pattern.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 aBigDecimal
.BigInteger
nextBigInteger()
Scans the next token of the input as aBigInteger
.BigInteger
nextBigInteger(int radix)
Scans the next token of the input as aBigInteger
.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 ofIterator
.Scanner
reset()
Resets this scanner.Scanner
skip(Pattern pattern)
Skips input that matches the specified pattern, ignoring delimiters.Scanner
skip(String pattern)
Skips input that matches a pattern constructed from the specified string.String
toString()
Returns the string representation of thisScanner
.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 specifiedString
.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.
-
-
-
Constructor Detail
-
Scanner
public Scanner(Readable source)
Constructs a newScanner
that produces values scanned from the specified source.- Parameters:
source
- A character source implementing theReadable
interface
-
Scanner
public Scanner(InputStream source)
Constructs a newScanner
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
- An input stream to be scanned
-
Scanner
public Scanner(InputStream source, String charsetName)
Constructs a newScanner
that produces values scanned from the specified input stream. Bytes from the stream are converted into characters using the specified charset.- Parameters:
source
- An input stream to be scannedcharsetName
- 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
public Scanner(File source) throws FileNotFoundException
Constructs a newScanner
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
- A file to be scanned- Throws:
FileNotFoundException
- if source is not found
-
Scanner
public Scanner(File source, String charsetName) throws FileNotFoundException
Constructs a newScanner
that produces values scanned from the specified file. Bytes from the file are converted into characters using the specified charset.- Parameters:
source
- A file to be scannedcharsetName
- The encoding type used to convert bytes from the file into characters to be scanned- Throws:
FileNotFoundException
- if source is not foundIllegalArgumentException
- if the specified encoding is not found
-
Scanner
public Scanner(Path source) throws IOException
Constructs a newScanner
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
- the path to the file to be scanned- Throws:
IOException
- if an I/O error occurs opening source- Since:
- 1.7
-
Scanner
public Scanner(Path source, String charsetName) throws IOException
Constructs a newScanner
that produces values scanned from the specified file. Bytes from the file are converted into characters using the specified charset.- Parameters:
source
- the path to the file to be scannedcharsetName
- The encoding type used to convert bytes from the file into characters to be scanned- Throws:
IOException
- if an I/O error occurs opening sourceIllegalArgumentException
- if the specified encoding is not found- Since:
- 1.7
-
Scanner
public Scanner(String source)
Constructs a newScanner
that produces values scanned from the specified string.- Parameters:
source
- A string to scan
-
Scanner
public Scanner(ReadableByteChannel source)
Constructs a newScanner
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
- A channel to scan
-
Scanner
public Scanner(ReadableByteChannel source, String charsetName)
Constructs a newScanner
that produces values scanned from the specified channel. Bytes from the source are converted into characters using the specified charset.- Parameters:
source
- A channel to scancharsetName
- 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
-
-
Method Detail
-
close
public 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
.- Specified by:
close
in interfaceCloseable
- Specified by:
close
in interfaceAutoCloseable
-
ioException
public IOException ioException()
Returns theIOException
last thrown by thisScanner
's underlyingReadable
. This method returnsnull
if no such exception exists.- Returns:
- the last exception thrown by this scanner's readable
-
delimiter
public Pattern delimiter()
Returns thePattern
thisScanner
is currently using to match delimiters.- Returns:
- this scanner's delimiting pattern.
-
useDelimiter
public Scanner useDelimiter(Pattern pattern)
Sets this scanner's delimiting pattern to the specified pattern.- Parameters:
pattern
- A delimiting pattern- Returns:
- this scanner
-
useDelimiter
public Scanner useDelimiter(String pattern)
Sets this scanner's delimiting pattern to a pattern constructed from the specifiedString
.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
- A string specifying a delimiting pattern- Returns:
- this scanner
-
locale
public 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:
- this scanner's locale
-
useLocale
public 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
- A string specifying the locale to use- Returns:
- this scanner
-
radix
public 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:
- the default radix of this scanner
-
useRadix
public 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 thanCharacter.MAX_RADIX
, then anIllegalArgumentException
is thrown.Invoking the
reset()
method will set the scanner's radix to10
.- Parameters:
radix
- The radix to use when scanning numbers- Returns:
- this scanner
- Throws:
IllegalArgumentException
- if radix is out of range
-
match
public MatchResult match()
Returns the match result of the last scanning operation performed by this scanner. This method throwsIllegalStateException
if no match has been performed, or if the last match was not successful.The various
next
methods ofScanner
make a match result available if they complete without throwing an exception. For instance, after an invocation of thenextInt()
method that returned an int, this method returns aMatchResult
for the search of the Integer regular expression defined above. Similarly thefindInLine(java.lang.String)
,findWithinHorizon(java.lang.String, int)
, andskip(java.util.regex.Pattern)
methods will make a match available if they succeed.- Returns:
- a match result for the last match operation
- Throws:
IllegalStateException
- If no match result is available
-
toString
public String toString()
Returns the string representation of this
Scanner
. The string representation of aScanner
contains information that may be useful for debugging. The exact format is unspecified.
-
hasNext
public 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.- Specified by:
hasNext
in interfaceIterator<String>
- Returns:
- true if and only if this scanner has another token
- Throws:
IllegalStateException
- if this scanner is closed- See Also:
Iterator
-
next
public 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 ofhasNext()
returnedtrue
.- Specified by:
next
in interfaceIterator<String>
- Returns:
- the next token
- Throws:
NoSuchElementException
- if no more tokens are availableIllegalStateException
- if this scanner is closed- See Also:
Iterator
-
remove
public void remove()
The remove operation is not supported by this implementation ofIterator
.- Specified by:
remove
in interfaceIterator<String>
- Throws:
UnsupportedOperationException
- if this method is invoked.- See Also:
Iterator
-
hasNext
public 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
- a string specifying the pattern to scan- Returns:
- true if and only if this scanner has another token matching the specified pattern
- Throws:
IllegalStateException
- if this scanner is closed
-
next
public 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
- a string specifying the pattern to scan- Returns:
- the next token
- Throws:
NoSuchElementException
- if no such tokens are availableIllegalStateException
- if this scanner is closed
-
hasNext
public 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
- the pattern to scan for- Returns:
- true if and only if this scanner has another token matching the specified pattern
- Throws:
IllegalStateException
- if this scanner is closed
-
next
public 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 ofhasNext(Pattern)
returnedtrue
. If the match is successful, the scanner advances past the input that matched the pattern.- Parameters:
pattern
- the pattern to scan for- Returns:
- the next token
- Throws:
NoSuchElementException
- if no more tokens are availableIllegalStateException
- if this scanner is closed
-
hasNextLine
public 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:
- true if and only if this scanner has another line of input
- Throws:
IllegalStateException
- if this scanner is closed
-
nextLine
public 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:
- the line that was skipped
- Throws:
NoSuchElementException
- if no line was foundIllegalStateException
- if this scanner is closed
-
findInLine
public 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
- a string specifying the pattern to search for- Returns:
- the text that matched the specified pattern
- Throws:
IllegalStateException
- if this scanner is closed
-
findInLine
public 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, thennull
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
- the pattern to scan for- Returns:
- the text that matched the specified pattern
- Throws:
IllegalStateException
- if this scanner is closed
-
findWithinHorizon
public 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
- a string specifying the pattern to search for- Returns:
- the text that matched the specified pattern
- Throws:
IllegalStateException
- if this scanner is closedIllegalArgumentException
- if horizon is negative
-
findWithinHorizon
public 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 (seeMatcher.useTransparentBounds(boolean)
andMatcher.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
- the pattern to scan for- Returns:
- the text that matched the specified pattern
- Throws:
IllegalStateException
- if this scanner is closedIllegalArgumentException
- if horizon is negative
-
skip
public 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
- a string specifying the pattern to skip over- Returns:
- this scanner
- Throws:
NoSuchElementException
- if the specified pattern is not foundIllegalStateException
- if this scanner is closed
-
skip
public 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
- a string specifying the pattern to skip over- Returns:
- this scanner
- Throws:
IllegalStateException
- if this scanner is closed
-
hasNextBoolean
public 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:
- true if and only if this scanner's next token is a valid boolean value
- Throws:
IllegalStateException
- if this scanner is closed
-
nextBoolean
public boolean nextBoolean()
Scans the next token of the input into a boolean value and returns that value. This method will throwInputMismatchException
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:
- the boolean scanned from the input
- Throws:
InputMismatchException
- if the next token is not a valid booleanNoSuchElementException
- if input is exhaustedIllegalStateException
- if this scanner is closed
-
hasNextByte
public 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 thenextByte()
method. The scanner does not advance past any input.- Returns:
- true if and only if this scanner's next token is a valid byte value
- Throws:
IllegalStateException
- if this scanner is closed
-
hasNextByte
public 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 thenextByte()
method. The scanner does not advance past any input.- Parameters:
radix
- the radix used to interpret the token as a byte value- Returns:
- true if and only if this scanner's next token is a valid byte value
- Throws:
IllegalStateException
- if this scanner is closed
-
nextByte
public 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:
- the byte scanned from the input
- Throws:
InputMismatchException
- if the next token does not match the Integer regular expression, or is out of rangeNoSuchElementException
- if input is exhaustedIllegalStateException
- if this scanner is closed
-
nextByte
public byte nextByte(int radix)
Scans the next token of the input as a byte. This method will throwInputMismatchException
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 toByte.parseByte
with the specified radix.- Parameters:
radix
- the radix used to interpret the token as a byte value- Returns:
- the byte scanned from the input
- Throws:
InputMismatchException
- if the next token does not match the Integer regular expression, or is out of rangeNoSuchElementException
- if input is exhaustedIllegalStateException
- if this scanner is closed
-
hasNextShort
public 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 thenextShort()
method. The scanner does not advance past any input.- Returns:
- 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
-
hasNextShort
public 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 thenextShort()
method. The scanner does not advance past any input.- Parameters:
radix
- the radix used to interpret the token as a short value- Returns:
- 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
-
nextShort
public 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:
- the short scanned from the input
- Throws:
InputMismatchException
- if the next token does not match the Integer regular expression, or is out of rangeNoSuchElementException
- if input is exhaustedIllegalStateException
- if this scanner is closed
-
nextShort
public short nextShort(int radix)
Scans the next token of the input as a short. This method will throwInputMismatchException
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 toShort.parseShort
with the specified radix.- Parameters:
radix
- the radix used to interpret the token as a short value- Returns:
- the short scanned from the input
- Throws:
InputMismatchException
- if the next token does not match the Integer regular expression, or is out of rangeNoSuchElementException
- if input is exhaustedIllegalStateException
- if this scanner is closed
-
hasNextInt
public 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 thenextInt()
method. The scanner does not advance past any input.- Returns:
- true if and only if this scanner's next token is a valid int value
- Throws:
IllegalStateException
- if this scanner is closed
-
hasNextInt
public 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 thenextInt()
method. The scanner does not advance past any input.- Parameters:
radix
- the radix used to interpret the token as an int value- Returns:
- true if and only if this scanner's next token is a valid int value
- Throws:
IllegalStateException
- if this scanner is closed
-
nextInt
public 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:
- the int scanned from the input
- Throws:
InputMismatchException
- if the next token does not match the Integer regular expression, or is out of rangeNoSuchElementException
- if input is exhaustedIllegalStateException
- if this scanner is closed
-
nextInt
public int nextInt(int radix)
Scans the next token of the input as an int. This method will throwInputMismatchException
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 toInteger.parseInt
with the specified radix.- Parameters:
radix
- the radix used to interpret the token as an int value- Returns:
- the int scanned from the input
- Throws:
InputMismatchException
- if the next token does not match the Integer regular expression, or is out of rangeNoSuchElementException
- if input is exhaustedIllegalStateException
- if this scanner is closed
-
hasNextLong
public 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 thenextLong()
method. The scanner does not advance past any input.- Returns:
- true if and only if this scanner's next token is a valid long value
- Throws:
IllegalStateException
- if this scanner is closed
-
hasNextLong
public 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 thenextLong()
method. The scanner does not advance past any input.- Parameters:
radix
- the radix used to interpret the token as a long value- Returns:
- true if and only if this scanner's next token is a valid long value
- Throws:
IllegalStateException
- if this scanner is closed
-
nextLong
public 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:
- the long scanned from the input
- Throws:
InputMismatchException
- if the next token does not match the Integer regular expression, or is out of rangeNoSuchElementException
- if input is exhaustedIllegalStateException
- if this scanner is closed
-
nextLong
public long nextLong(int radix)
Scans the next token of the input as a long. This method will throwInputMismatchException
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 toLong.parseLong
with the specified radix.- Parameters:
radix
- the radix used to interpret the token as an int value- Returns:
- the long scanned from the input
- Throws:
InputMismatchException
- if the next token does not match the Integer regular expression, or is out of rangeNoSuchElementException
- if input is exhaustedIllegalStateException
- if this scanner is closed
-
hasNextFloat
public boolean hasNextFloat()
Returns true if the next token in this scanner's input can be interpreted as a float value using thenextFloat()
method. The scanner does not advance past any input.- Returns:
- true if and only if this scanner's next token is a valid float value
- Throws:
IllegalStateException
- if this scanner is closed
-
nextFloat
public float nextFloat()
Scans the next token of the input as a float. This method will throwInputMismatchException
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 toFloat.parseFloat
. If the token matches the localized NaN or infinity strings, then either "Nan" or "Infinity" is passed toFloat.parseFloat
as appropriate.- Returns:
- the float scanned from the input
- Throws:
InputMismatchException
- if the next token does not match the Float regular expression, or is out of rangeNoSuchElementException
- if input is exhaustedIllegalStateException
- if this scanner is closed
-
hasNextDouble
public boolean hasNextDouble()
Returns true if the next token in this scanner's input can be interpreted as a double value using thenextDouble()
method. The scanner does not advance past any input.- Returns:
- true if and only if this scanner's next token is a valid double value
- Throws:
IllegalStateException
- if this scanner is closed
-
nextDouble
public double nextDouble()
Scans the next token of the input as a double. This method will throwInputMismatchException
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 toDouble.parseDouble
. If the token matches the localized NaN or infinity strings, then either "Nan" or "Infinity" is passed toDouble.parseDouble
as appropriate.- Returns:
- the double scanned from the input
- Throws:
InputMismatchException
- 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 closed
-
hasNextBigInteger
public boolean hasNextBigInteger()
Returns true if the next token in this scanner's input can be interpreted as aBigInteger
in the default radix using thenextBigInteger()
method. The scanner does not advance past any input.- Returns:
- true if and only if this scanner's next token is a valid
BigInteger
- Throws:
IllegalStateException
- if this scanner is closed
-
hasNextBigInteger
public boolean hasNextBigInteger(int radix)
Returns true if the next token in this scanner's input can be interpreted as aBigInteger
in the specified radix using thenextBigInteger()
method. The scanner does not advance past any input.- Parameters:
radix
- the radix used to interpret the token as an integer- Returns:
- true if and only if this scanner's next token is a valid
BigInteger
- Throws:
IllegalStateException
- if this scanner is closed
-
nextBigInteger
public BigInteger nextBigInteger()
Scans the next token of the input as aBigInteger
.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:
- the BigInteger scanned from the input
- Throws:
InputMismatchException
- 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 closed
-
nextBigInteger
public BigInteger nextBigInteger(int radix)
Scans the next token of the input as aBigInteger
.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 theBigInteger(String, int)
constructor with the specified radix.- Parameters:
radix
- the radix used to interpret the token- Returns:
- the BigInteger scanned from the input
- Throws:
InputMismatchException
- 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 closed
-
hasNextBigDecimal
public boolean hasNextBigDecimal()
Returns true if the next token in this scanner's input can be interpreted as aBigDecimal
using thenextBigDecimal()
method. The scanner does not advance past any input.- Returns:
- true if and only if this scanner's next token is a valid
BigDecimal
- Throws:
IllegalStateException
- if this scanner is closed
-
nextBigDecimal
public BigDecimal nextBigDecimal()
Scans the next token of the input as aBigDecimal
.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 theBigDecimal(String)
constructor.- Returns:
- the BigDecimal scanned from the input
- Throws:
InputMismatchException
- 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 closed
-
reset
public Scanner reset()
Resets this scanner.Resetting a scanner discards all of its explicit state information which may have been changed by invocations of
useDelimiter(java.util.regex.Pattern)
,useLocale(java.util.Locale)
, oruseRadix(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:
- this scanner
- Since:
- 1.6
-
-
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