Class StringTokenizer

java.lang.Object
com.ibm.icu.util.StringTokenizer
All Implemented Interfaces:
Enumeration<Object>

public final class StringTokenizer extends Object implements Enumeration<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 the returnDelims and coalesceDelims flags having the value true or false:

  • 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 is true, 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
 
Author:
syn wee
  • Constructor Details

    • StringTokenizer

      public StringTokenizer(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:
      NullPointerException - if str is null
    • StringTokenizer

      @Deprecated public StringTokenizer(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:
      NullPointerException - if str is null
    • StringTokenizer

      public StringTokenizer(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:
      NullPointerException - if str is null
    • StringTokenizer

      public StringTokenizer(String str, 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:
      NullPointerException - if str is null
    • StringTokenizer

      @Deprecated public StringTokenizer(String str, 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:
      NullPointerException - if str is null
    • StringTokenizer

      public StringTokenizer(String str, 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:
      NullPointerException - if str is null
    • StringTokenizer

      public StringTokenizer(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:
      NullPointerException - if str is null
  • Method Details

    • 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.
    • nextToken

      public String nextToken()
      Returns the next token from this string tokenizer.
      Returns:
      the next token from this string tokenizer.
      Throws:
      NoSuchElementException - if there are no more tokens in this tokenizer's string.
    • nextToken

      public String nextToken(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:
      NoSuchElementException - if there are no more tokens in this tokenizer's string.
    • nextToken

      public 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:
      NoSuchElementException - if there are no more tokens in this tokenizer's string.
    • hasMoreElements

      public boolean hasMoreElements()
      Returns the same value as the hasMoreTokens method. It exists so that this class can implement the Enumeration interface.
      Specified by:
      hasMoreElements in interface Enumeration<Object>
      Returns:
      true if there are more tokens; false otherwise.
      See Also:
    • nextElement

      public Object nextElement()
      Returns the same value as the nextToken method, except that its declared return value is Object rather than String. It exists so that this class can implement the Enumeration interface.
      Specified by:
      nextElement in interface Enumeration<Object>
      Returns:
      the next token in the string.
      Throws:
      NoSuchElementException - if there are no more tokens in this tokenizer's string.
      See Also:
    • countTokens

      public int countTokens()
      Calculates the number of times that this tokenizer's nextToken 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: