Class StringTokenizer
- java.lang.Object
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- com.ibm.icu.util.StringTokenizer
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- All Implemented Interfaces:
java.util.Enumeration<java.lang.Object>
public final class StringTokenizer extends java.lang.Object implements java.util.Enumeration<java.lang.Object>
.The string tokenizer class allows an application to break a string into tokens by performing code point comparison. The
StringTokenizer
methods do not distinguish among identifiers, numbers, and quoted strings, nor do they recognize and skip comments.The set of delimiters (the codepoints that separate tokens) may be specified either at creation time or on a per-token basis.
An instance of
StringTokenizer
behaves in one of three ways, depending on whether it was created with thereturnDelims
andcoalesceDelims
flags having the valuetrue
orfalse
:- If returnDelims is
false
, delimiter code points serve to separate tokens. A token is a maximal sequence of consecutive code points that are not delimiters. - If returnDelims is
true
, delimiter code points are themselves considered to be tokens. In this case, if coalesceDelims istrue
, such tokens will be the maximal sequence of consecutive code points that are delimiters. If coalesceDelims is false, a token will be received for each delimiter code point.
A token is thus either one delimiter code point, a maximal sequence of consecutive code points that are delimiters, or a maximal sequence of consecutive code points that are not delimiters.
A StringTokenizer object internally maintains a current position within the string to be tokenized. Some operations advance this current position past the code point processed.
A token is returned by taking a substring of the string that was used to create the StringTokenizer object.
Example of the use of the default delimiter tokenizer.
StringTokenizer st = new StringTokenizer("this is a test"); while (st.hasMoreTokens()) { println(st.nextToken()); }
prints the following output:
this is a test
Example of the use of the tokenizer with user specified delimiter.
StringTokenizer st = new StringTokenizer( "this is a test with supplementary characters \ud800\ud800\udc00\udc00", " \ud800\udc00"); while (st.hasMoreTokens()) { println(st.nextToken()); }
prints the following output:
this is a test with supplementary characters \ud800 \udc00
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Field Summary
Fields Modifier and Type Field Description private static UnicodeSet
DEFAULT_DELIMITERS_
Default set of delimiters \t\n\r\fprivate boolean[]
delims
private static UnicodeSet
EMPTY_DELIMITER_
A empty delimiter UnicodeSet, used when user specified null delimitersprivate boolean
m_coalesceDelimiters_
Flag indicating whether to coalesce runs of delimiters into single tokensprivate UnicodeSet
m_delimiters_
UnicodeSet containing delimitersprivate int
m_length_
Length of m_source_private int
m_nextOffset_
Current position in string to parse for tokensprivate boolean
m_returnDelimiters_
Flag indicator if delimiters are to be treated as tokens tooprivate java.lang.String
m_source_
String to parse for tokensprivate int[]
m_tokenLimit_
Array of pre-calculated tokens limit indexes in source string.private int
m_tokenOffset_
Current offset to the token array.private int
m_tokenSize_
Size of the token array.private int[]
m_tokenStart_
Array of pre-calculated tokens start indexes in source string terminated by -1.private static int
TOKEN_SIZE_
Array size increments
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Constructor Summary
Constructors Constructor Description StringTokenizer(java.lang.String str)
Constructs a string tokenizer for the specified string.StringTokenizer(java.lang.String str, UnicodeSet delim)
Constructs a string tokenizer for the specified string.StringTokenizer(java.lang.String str, UnicodeSet delim, boolean returndelims)
Constructs a string tokenizer for the specified string.StringTokenizer(java.lang.String str, UnicodeSet delim, boolean returndelims, boolean coalescedelims)
Deprecated.This API is ICU internal only.StringTokenizer(java.lang.String str, java.lang.String delim)
Constructs a string tokenizer for the specified string.StringTokenizer(java.lang.String str, java.lang.String delim, boolean returndelims)
Constructs a string tokenizer for the specified string.StringTokenizer(java.lang.String str, java.lang.String delim, boolean returndelims, boolean coalescedelims)
Deprecated.This API is ICU internal only.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description (package private) void
checkDelimiters()
int
countTokens()
Calculates the number of times that this tokenizer'snextToken
method can be called before it generates an exception.private int
getNextDelimiter(int offset)
Gets the index of the next delimiter after offsetprivate int
getNextNonDelimiter(int offset)
Gets the index of the next non-delimiter after m_nextOffset_boolean
hasMoreElements()
Returns the same value as thehasMoreTokens
method.boolean
hasMoreTokens()
Tests if there are more tokens available from this tokenizer's string.java.lang.Object
nextElement()
Returns the same value as thenextToken
method, except that its declared return value isObject
rather thanString
.java.lang.String
nextToken()
Returns the next token from this string tokenizer.java.lang.String
nextToken(UnicodeSet delim)
Returns the next token in this string tokenizer's string.java.lang.String
nextToken(java.lang.String delim)
Returns the next token in this string tokenizer's string.
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Field Detail
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m_tokenOffset_
private int m_tokenOffset_
Current offset to the token array. If the array token is not set up yet, this value is a -1
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m_tokenSize_
private int m_tokenSize_
Size of the token array. If the array token is not set up yet, this value is a -1
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m_tokenStart_
private int[] m_tokenStart_
Array of pre-calculated tokens start indexes in source string terminated by -1. This is only set up during countTokens() and only stores the remaining tokens, not all tokens including parsed ones
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m_tokenLimit_
private int[] m_tokenLimit_
Array of pre-calculated tokens limit indexes in source string. This is only set up during countTokens() and only stores the remaining tokens, not all tokens including parsed ones
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m_delimiters_
private UnicodeSet m_delimiters_
UnicodeSet containing delimiters
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m_source_
private java.lang.String m_source_
String to parse for tokens
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m_length_
private int m_length_
Length of m_source_
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m_nextOffset_
private int m_nextOffset_
Current position in string to parse for tokens
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m_returnDelimiters_
private boolean m_returnDelimiters_
Flag indicator if delimiters are to be treated as tokens too
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m_coalesceDelimiters_
private boolean m_coalesceDelimiters_
Flag indicating whether to coalesce runs of delimiters into single tokens
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DEFAULT_DELIMITERS_
private static final UnicodeSet DEFAULT_DELIMITERS_
Default set of delimiters \t\n\r\f
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TOKEN_SIZE_
private static final int TOKEN_SIZE_
Array size increments- See Also:
- Constant Field Values
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EMPTY_DELIMITER_
private static final UnicodeSet EMPTY_DELIMITER_
A empty delimiter UnicodeSet, used when user specified null delimiters
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delims
private boolean[] delims
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Constructor Detail
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StringTokenizer
public StringTokenizer(java.lang.String str, UnicodeSet delim, boolean returndelims)
Constructs a string tokenizer for the specified string. All characters in the delim argument are the delimiters for separating tokens.If the returnDelims flag is false, the delimiter characters are skipped and only serve as separators between tokens.
If the returnDelims flag is true, then the delimiter characters are also returned as tokens, one per delimiter.
- Parameters:
str
- a string to be parsed.delim
- the delimiters.returndelims
- flag indicating whether to return the delimiters as tokens.- Throws:
java.lang.NullPointerException
- if str is null
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StringTokenizer
@Deprecated public StringTokenizer(java.lang.String str, UnicodeSet delim, boolean returndelims, boolean coalescedelims)
Deprecated.This API is ICU internal only.Constructs a string tokenizer for the specified string. All characters in the delim argument are the delimiters for separating tokens.If the returnDelims flag is false, the delimiter characters are skipped and only serve as separators between tokens.
If the returnDelims flag is true, then the delimiter characters are also returned as tokens. If coalescedelims is true, one token is returned for each run of delimiter characters, otherwise one token is returned per delimiter. Since surrogate pairs can be delimiters, the returned token might be two chars in length.
- Parameters:
str
- a string to be parsed.delim
- the delimiters.returndelims
- flag indicating whether to return the delimiters as tokens.coalescedelims
- flag indicating whether to return a run of delimiters as a single token or as one token per delimiter. This only takes effect if returndelims is true.- Throws:
java.lang.NullPointerException
- if str is null
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StringTokenizer
public StringTokenizer(java.lang.String str, UnicodeSet delim)
Constructs a string tokenizer for the specified string. The characters in the delim argument are the delimiters for separating tokens.Delimiter characters themselves will not be treated as tokens.
- Parameters:
str
- a string to be parsed.delim
- the delimiters.- Throws:
java.lang.NullPointerException
- if str is null
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StringTokenizer
public StringTokenizer(java.lang.String str, java.lang.String delim, boolean returndelims)
Constructs a string tokenizer for the specified string. All characters in the delim argument are the delimiters for separating tokens.
If the returnDelims flag is false, the delimiter characters are skipped and only serve as separators between tokens.
If the returnDelims flag is true, then the delimiter characters are also returned as tokens, one per delimiter.
- Parameters:
str
- a string to be parsed.delim
- the delimiters.returndelims
- flag indicating whether to return the delimiters as tokens.- Throws:
java.lang.NullPointerException
- if str is null
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StringTokenizer
@Deprecated public StringTokenizer(java.lang.String str, java.lang.String delim, boolean returndelims, boolean coalescedelims)
Deprecated.This API is ICU internal only.Constructs a string tokenizer for the specified string. All characters in the delim argument are the delimiters for separating tokens.
If the returnDelims flag is false, the delimiter characters are skipped and only serve as separators between tokens.
If the returnDelims flag is true, then the delimiter characters are also returned as tokens. If coalescedelims is true, one token is returned for each run of delimiter characters, otherwise one token is returned per delimiter. Since surrogate pairs can be delimiters, the returned token might be two chars in length.
- Parameters:
str
- a string to be parsed.delim
- the delimiters.returndelims
- flag indicating whether to return the delimiters as tokens.coalescedelims
- flag indicating whether to return a run of delimiters as a single token or as one token per delimiter. This only takes effect if returndelims is true.- Throws:
java.lang.NullPointerException
- if str is null
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StringTokenizer
public StringTokenizer(java.lang.String str, java.lang.String delim)
Constructs a string tokenizer for the specified string. The characters in the delim argument are the delimiters for separating tokens.
Delimiter characters themselves will not be treated as tokens.
- Parameters:
str
- a string to be parsed.delim
- the delimiters.- Throws:
java.lang.NullPointerException
- if str is null
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StringTokenizer
public StringTokenizer(java.lang.String str)
Constructs a string tokenizer for the specified string. The tokenizer uses the default delimiter set, which is " \t\n\r\f": the space character, the tab character, the newline character, the carriage-return character, and the form-feed character.
Delimiter characters themselves will not be treated as tokens.
- Parameters:
str
- a string to be parsed- Throws:
java.lang.NullPointerException
- if str is null
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Method Detail
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hasMoreTokens
public boolean hasMoreTokens()
Tests if there are more tokens available from this tokenizer's string. If this method returns true, then a subsequent call to nextToken with no argument will successfully return a token.- Returns:
true
if and only if there is at least one token in the string after the current position;false
otherwise.
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nextToken
public java.lang.String nextToken()
Returns the next token from this string tokenizer.- Returns:
- the next token from this string tokenizer.
- Throws:
java.util.NoSuchElementException
- if there are no more tokens in this tokenizer's string.
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nextToken
public java.lang.String nextToken(java.lang.String delim)
Returns the next token in this string tokenizer's string. First, the set of characters considered to be delimiters by this StringTokenizer object is changed to be the characters in the string delim. Then the next token in the string after the current position is returned. The current position is advanced beyond the recognized token. The new delimiter set remains the default after this call.- Parameters:
delim
- the new delimiters.- Returns:
- the next token, after switching to the new delimiter set.
- Throws:
java.util.NoSuchElementException
- if there are no more tokens in this tokenizer's string.
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nextToken
public java.lang.String nextToken(UnicodeSet delim)
Returns the next token in this string tokenizer's string. First, the set of characters considered to be delimiters by this StringTokenizer object is changed to be the characters in the string delim. Then the next token in the string after the current position is returned. The current position is advanced beyond the recognized token. The new delimiter set remains the default after this call.- Parameters:
delim
- the new delimiters.- Returns:
- the next token, after switching to the new delimiter set.
- Throws:
java.util.NoSuchElementException
- if there are no more tokens in this tokenizer's string.
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hasMoreElements
public boolean hasMoreElements()
Returns the same value as thehasMoreTokens
method. It exists so that this class can implement theEnumeration
interface.- Specified by:
hasMoreElements
in interfacejava.util.Enumeration<java.lang.Object>
- Returns:
true
if there are more tokens;false
otherwise.- See Also:
hasMoreTokens()
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nextElement
public java.lang.Object nextElement()
Returns the same value as thenextToken
method, except that its declared return value isObject
rather thanString
. It exists so that this class can implement theEnumeration
interface.- Specified by:
nextElement
in interfacejava.util.Enumeration<java.lang.Object>
- Returns:
- the next token in the string.
- Throws:
java.util.NoSuchElementException
- if there are no more tokens in this tokenizer's string.- See Also:
nextToken()
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countTokens
public int countTokens()
Calculates the number of times that this tokenizer'snextToken
method can be called before it generates an exception. The current position is not advanced.- Returns:
- the number of tokens remaining in the string using the current delimiter set.
- See Also:
nextToken()
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getNextDelimiter
private int getNextDelimiter(int offset)
Gets the index of the next delimiter after offset- Parameters:
offset
- to the source string- Returns:
- offset of the immediate next delimiter, otherwise (- source string length - 1) if there are no more delimiters after m_nextOffset
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getNextNonDelimiter
private int getNextNonDelimiter(int offset)
Gets the index of the next non-delimiter after m_nextOffset_- Parameters:
offset
- to the source string- Returns:
- offset of the immediate next non-delimiter, otherwise (- source string length - 1) if there are no more delimiters after m_nextOffset
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checkDelimiters
void checkDelimiters()
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