Package org.apache.commons.text

Class StringTokenizer

java.lang.Object
org.apache.commons.text.StringTokenizer
All Implemented Interfaces:
Cloneable, Iterator<String>, ListIterator<String>
public class StringTokenizer extends Object implements ListIterator<String>, Cloneable
Tokenizes a string based on delimiters (separators) and supporting quoting and ignored character concepts.

This class can split a String into many smaller strings. It aims to do a similar job to StringTokenizer, however it offers much more control and flexibility including implementing the ListIterator interface. By default, it is set up like StringTokenizer.

The input String is split into a number of tokens. Each token is separated from the next String by a delimiter. One or more delimiter characters must be specified.

Each token may be surrounded by quotes. The quote matcher specifies the quote character(s). A quote may be escaped within a quoted section by duplicating itself.

Between each token and the delimiter are potentially characters that need trimming. The trimmer matcher specifies these characters. One usage might be to trim whitespace characters.

At any point outside the quotes there might potentially be invalid characters. The ignored matcher specifies these characters to be removed. One usage might be to remove new line characters.

Empty tokens may be removed or returned as null. 

 "a,b,c"         - Three tokens "a","b","c"   (comma delimiter)
 " a, b , c "    - Three tokens "a","b","c"   (default CSV processing trims whitespace)
 "a, ", b ,", c" - Three tokens "a, " , " b ", ", c" (quoted text untouched)
StringTokenizer properties and options
Property Type Default
delim CharSetMatcher { \t\n\r\f}
quote NoneMatcher {}
ignore NoneMatcher {}
emptyTokenAsNull boolean false
ignoreEmptyTokens boolean true
Since:
1.3

  • Constructor Details

    • StringTokenizer

      public StringTokenizer()
      Constructs a tokenizer splitting on space, tab, newline and form feed as per StringTokenizer, but with no text to tokenize.

      This constructor is normally used with reset(String).

    • StringTokenizer

      public StringTokenizer(char[] input)
      Constructs a tokenizer splitting on space, tab, newline and form feed as per StringTokenizer.
      Parameters:
      input - the string which is to be parsed, not cloned

    • StringTokenizer

      public StringTokenizer(char[] input, char delim)
      Constructs a tokenizer splitting on the specified character.
      Parameters:
      input - the string which is to be parsed, not cloned
      delim - the field delimiter character

    • StringTokenizer

      public StringTokenizer(char[] input, char delim, char quote)
      Constructs a tokenizer splitting on the specified delimiter character and handling quotes using the specified quote character.
      Parameters:
      input - the string which is to be parsed, not cloned
      delim - the field delimiter character
      quote - the field quoted string character

    • StringTokenizer

      public StringTokenizer(char[] input, String delim)
      Constructs a tokenizer splitting on the specified string.
      Parameters:
      input - the string which is to be parsed, not cloned
      delim - the field delimiter string

    • StringTokenizer

      public StringTokenizer(char[] input, StringMatcher delim)
      Constructs a tokenizer splitting using the specified delimiter matcher.
      Parameters:
      input - the string which is to be parsed, not cloned
      delim - the field delimiter matcher

    • StringTokenizer

      public StringTokenizer(char[] input, StringMatcher delim, StringMatcher quote)
      Constructs a tokenizer splitting using the specified delimiter matcher and handling quotes using the specified quote matcher.
      Parameters:
      input - the string which is to be parsed, not cloned
      delim - the field delimiter character
      quote - the field quoted string character

    • StringTokenizer

      public StringTokenizer(String input)
      Constructs a tokenizer splitting on space, tab, newline and form feed as per StringTokenizer.
      Parameters:
      input - the string which is to be parsed

    • StringTokenizer

      public StringTokenizer(String input, char delim)
      Constructs a tokenizer splitting on the specified delimiter character.
      Parameters:
      input - the string which is to be parsed
      delim - the field delimiter character

    • StringTokenizer

      public StringTokenizer(String input, char delim, char quote)
      Constructs a tokenizer splitting on the specified delimiter character and handling quotes using the specified quote character.
      Parameters:
      input - the string which is to be parsed
      delim - the field delimiter character
      quote - the field quoted string character

    • StringTokenizer

      public StringTokenizer(String input, String delim)
      Constructs a tokenizer splitting on the specified delimiter string.
      Parameters:
      input - the string which is to be parsed
      delim - the field delimiter string

    • StringTokenizer

      public StringTokenizer(String input, StringMatcher delim)
      Constructs a tokenizer splitting using the specified delimiter matcher.
      Parameters:
      input - the string which is to be parsed
      delim - the field delimiter matcher

    • StringTokenizer

      public StringTokenizer(String input, StringMatcher delim, StringMatcher quote)
      Constructs a tokenizer splitting using the specified delimiter matcher and handling quotes using the specified quote matcher.
      Parameters:
      input - the string which is to be parsed
      delim - the field delimiter matcher
      quote - the field quoted string matcher

  • Method Details

    • getCSVInstance

      public static StringTokenizer getCSVInstance()
      Gets a new tokenizer instance which parses Comma Separated Value strings initializing it with the given input. The default for CSV processing will be trim whitespace from both ends (which can be overridden with the setTrimmer method).

      You must call a "reset" method to set the string which you want to parse.

      Returns:
      a new tokenizer instance which parses Comma Separated Value strings

    • getCSVInstance

      public static StringTokenizer getCSVInstance(char[] input)
      Gets a new tokenizer instance which parses Comma Separated Value strings initializing it with the given input. The default for CSV processing will be trim whitespace from both ends (which can be overridden with the setTrimmer method).
      Parameters:
      input - the text to parse
      Returns:
      a new tokenizer instance which parses Comma Separated Value strings

    • getCSVInstance

      public static StringTokenizer getCSVInstance(String input)
      Gets a new tokenizer instance which parses Comma Separated Value strings initializing it with the given input. The default for CSV processing will be trim whitespace from both ends (which can be overridden with the setTrimmer method).
      Parameters:
      input - the text to parse
      Returns:
      a new tokenizer instance which parses Comma Separated Value strings

    • getTSVInstance

      public static StringTokenizer getTSVInstance()
      Gets a new tokenizer instance which parses Tab Separated Value strings. The default for CSV processing will be trim whitespace from both ends (which can be overridden with the setTrimmer method).

      You must call a "reset" method to set the string which you want to parse.

      Returns:
      a new tokenizer instance which parses Tab Separated Value strings.

    • getTSVInstance

      public static StringTokenizer getTSVInstance(char[] input)
      Gets a new tokenizer instance which parses Tab Separated Value strings. The default for CSV processing will be trim whitespace from both ends (which can be overridden with the setTrimmer method).
      Parameters:
      input - the string to parse
      Returns:
      a new tokenizer instance which parses Tab Separated Value strings.

    • getTSVInstance

      public static StringTokenizer getTSVInstance(String input)
      Gets a new tokenizer instance which parses Tab Separated Value strings. The default for CSV processing will be trim whitespace from both ends (which can be overridden with the setTrimmer method).
      Parameters:
      input - the string to parse
      Returns:
      a new tokenizer instance which parses Tab Separated Value strings.

    • add

      public void add(String obj)
      Unsupported ListIterator operation.
      Specified by:
      add in interface ListIterator<String>
      Parameters:
      obj - this parameter ignored.
      Throws:
      UnsupportedOperationException - always

    • clone

      public Object clone()
      Creates a new instance of this Tokenizer. The new instance is reset so that it will be at the start of the token list. If a CloneNotSupportedException is caught, return null.
      Overrides:
      clone in class Object
      Returns:
      a new instance of this Tokenizer which has been reset.

    • getContent

      public String getContent()
      Gets the String content that the tokenizer is parsing.
      Returns:
      The string content being parsed

    • getDelimiterMatcher

      public StringMatcher getDelimiterMatcher()
      Gets the field delimiter matcher.
      Returns:
      The delimiter matcher in use

    • getIgnoredMatcher

      public StringMatcher getIgnoredMatcher()
      Gets the ignored character matcher.

      These characters are ignored when parsing the String, unless they are within a quoted region. The default value is not to ignore anything.

      Returns:
      The ignored matcher in use

    • getQuoteMatcher

      public StringMatcher getQuoteMatcher()
      Gets the quote matcher currently in use.

      The quote character is used to wrap data between the tokens. This enables delimiters to be entered as data. The default value is '"' (double quote).

      Returns:
      The quote matcher in use

    • getTokenArray

      public String[] getTokenArray()
      Gets a copy of the full token list as an independent modifiable array.
      Returns:
      The tokens as a String array

    • getTokenList

      public List<String> getTokenList()
      Gets a copy of the full token list as an independent modifiable list.
      Returns:
      The tokens as a String list

    • getTrimmerMatcher

      public StringMatcher getTrimmerMatcher()
      Gets the trimmer character matcher.

      These characters are trimmed off on each side of the delimiter until the token or quote is found. The default value is not to trim anything.

      Returns:
      The trimmer matcher in use

    • hasNext

      public boolean hasNext()
      Tests whether there are any more tokens.
      Specified by:
      hasNext in interface Iterator<String>
      Specified by:
      hasNext in interface ListIterator<String>
      Returns:
      true if there are more tokens

    • hasPrevious

      public boolean hasPrevious()
      Tests whether there are any previous tokens that can be iterated to.
      Specified by:
      hasPrevious in interface ListIterator<String>
      Returns:
      true if there are previous tokens

    • isEmptyTokenAsNull

      public boolean isEmptyTokenAsNull()
      Tests whether the tokenizer currently returns empty tokens as null. The default for this property is false.
      Returns:
      true if empty tokens are returned as null

    • isIgnoreEmptyTokens

      public boolean isIgnoreEmptyTokens()
      Tests whether the tokenizer currently ignores empty tokens. The default for this property is true.
      Returns:
      true if empty tokens are not returned

    • next

      public String next()
      Gets the next token.
      Specified by:
      next in interface Iterator<String>
      Specified by:
      next in interface ListIterator<String>
      Returns:
      The next String token
      Throws:
      NoSuchElementException - if there are no more elements

    • nextIndex

      public int nextIndex()
      Gets the index of the next token to return.
      Specified by:
      nextIndex in interface ListIterator<String>
      Returns:
      The next token index

    • nextToken

      public String nextToken()
      Gets the next token from the String. Equivalent to next() except it returns null rather than throwing NoSuchElementException when no tokens remain.
      Returns:
      The next sequential token, or null when no more tokens are found

    • previous

      public String previous()
      Gets the token previous to the last returned token.
      Specified by:
      previous in interface ListIterator<String>
      Returns:
      The previous token

    • previousIndex

      public int previousIndex()
      Gets the index of the previous token.
      Specified by:
      previousIndex in interface ListIterator<String>
      Returns:
      The previous token index

    • previousToken

      public String previousToken()
      Gets the previous token from the String.
      Returns:
      The previous sequential token, or null when no more tokens are found

    • remove

      public void remove()
      Throws UnsupportedOperationException for this unsupported ListIterator operation.
      Specified by:
      remove in interface Iterator<String>
      Specified by:
      remove in interface ListIterator<String>
      Throws:
      UnsupportedOperationException - always

    • reset

      public StringTokenizer reset()
      Resets this tokenizer, forgetting all parsing and iteration already completed.

      This method allows the same tokenizer to be reused for the same String.

      Returns:
      this, to enable chaining

    • reset

      public StringTokenizer reset(char[] input)
      Resets this tokenizer, giving it a new input string to parse. In this manner you can re-use a tokenizer with the same settings on multiple input lines.
      Parameters:
      input - the new character array to tokenize, not cloned, null sets no text to parse
      Returns:
      this, to enable chaining

    • reset

      public StringTokenizer reset(String input)
      Resets this tokenizer, giving it a new input string to parse. In this manner you can re-use a tokenizer with the same settings on multiple input lines.
      Parameters:
      input - the new string to tokenize, null sets no text to parse
      Returns:
      this, to enable chaining

    • set

      public void set(String obj)
      Throws UnsupportedOperationException for this unsupported ListIterator operation.
      Specified by:
      set in interface ListIterator<String>
      Parameters:
      obj - this parameter ignored.
      Throws:
      UnsupportedOperationException - always

    • setDelimiterChar

      public StringTokenizer setDelimiterChar(char delim)
      Sets the field delimiter character.
      Parameters:
      delim - the delimiter character to use
      Returns:
      this, to enable chaining

    • setDelimiterMatcher

      public StringTokenizer setDelimiterMatcher(StringMatcher delim)
      Sets the field delimiter matcher.

      The delimiter is used to separate one token from another.

      Parameters:
      delim - the delimiter matcher to use
      Returns:
      this, to enable chaining

    • setDelimiterString

      public StringTokenizer setDelimiterString(String delim)
      Sets the field delimiter string.
      Parameters:
      delim - the delimiter string to use
      Returns:
      this, to enable chaining

    • setEmptyTokenAsNull

      public StringTokenizer setEmptyTokenAsNull(boolean emptyAsNull)
      Sets whether the tokenizer should return empty tokens as null. The default for this property is false.
      Parameters:
      emptyAsNull - whether empty tokens are returned as null
      Returns:
      this, to enable chaining

    • setIgnoredChar

      public StringTokenizer setIgnoredChar(char ignored)
      Sets the character to ignore.

      This character is ignored when parsing the String, unless it is within a quoted region.

      Parameters:
      ignored - the ignored character to use
      Returns:
      this, to enable chaining

    • setIgnoredMatcher

      public StringTokenizer setIgnoredMatcher(StringMatcher ignored)
      Sets the matcher for characters to ignore.

      These characters are ignored when parsing the String, unless they are within a quoted region.

      Parameters:
      ignored - the ignored matcher to use, null ignored
      Returns:
      this, to enable chaining

    • setIgnoreEmptyTokens

      public StringTokenizer setIgnoreEmptyTokens(boolean ignoreEmptyTokens)
      Sets whether the tokenizer should ignore and not return empty tokens. The default for this property is true.
      Parameters:
      ignoreEmptyTokens - whether empty tokens are not returned
      Returns:
      this, to enable chaining

    • setQuoteChar

      public StringTokenizer setQuoteChar(char quote)
      Sets the quote character to use.

      The quote character is used to wrap data between the tokens. This enables delimiters to be entered as data.

      Parameters:
      quote - the quote character to use
      Returns:
      this, to enable chaining

    • setQuoteMatcher

      public StringTokenizer setQuoteMatcher(StringMatcher quote)
      Sets the quote matcher to use.

      The quote character is used to wrap data between the tokens. This enables delimiters to be entered as data.

      Parameters:
      quote - the quote matcher to use, null ignored
      Returns:
      this, to enable chaining

    • setTrimmerMatcher

      public StringTokenizer setTrimmerMatcher(StringMatcher trimmer)
      Sets the matcher for characters to trim.

      These characters are trimmed off on each side of the delimiter until the token or quote is found.

      Parameters:
      trimmer - the trimmer matcher to use, null ignored
      Returns:
      this, to enable chaining

    • size

      public int size()
      Gets the number of tokens found in the String.
      Returns:
      The number of matched tokens

    • tokenize

      protected List<String> tokenize(char[] srcChars, int offset, int count)
      Internal method to performs the tokenization.

      Most users of this class do not need to call this method. This method will be called automatically by other (public) methods when required.

      This method exists to allow subclasses to add code before or after the tokenization. For example, a subclass could alter the character array, offset or count to be parsed, or call the tokenizer multiple times on multiple strings. It is also be possible to filter the results.

      StrTokenizer will always pass a zero offset and a count equal to the length of the array to this method, however a subclass may pass other values, or even an entirely different array.

      Parameters:
      srcChars - the character array being tokenized, may be null
      offset - the start position within the character array, must be valid
      count - the number of characters to tokenize, must be valid
      Returns:
      The modifiable list of String tokens, unmodifiable if null array or zero count

    • toString

      public String toString()
      Gets the String content that the tokenizer is parsing.
      Overrides:
      toString in class Object
      Returns:
      The string content being parsed