Java Doc for StringTokenizer.java in  » 6.0-JDK-Core » Collections-Jar-Zip-Logging-regex » java » util » Java Source Code / Java DocumentationJava Source Code and Java Documentation

The set of delimiters (the characters that separate tokens) may be specified either at creation time or on a per-token basis.

An instance of StringTokenizer behaves in one of two ways, depending on whether it was created with the returnDelims flag having the value true or false:

• If the flag is false, delimiter characters serve to separate tokens. A token is a maximal sequence of consecutive characters that are not delimiters.
• If the flag is true, delimiter characters are themselves considered to be tokens. A token is thus either one delimiter character, or a maximal sequence of consecutive characters 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 characters processed.

A token is returned by taking a substring of the string that was used to create the StringTokenizer object.

The following is one example of the use of the tokenizer. The code:

 StringTokenizer st = new StringTokenizer("this is a test");
 while (st.hasMoreTokens()) {
 System.out.println(st.nextToken());
 }
 

prints the following output:

 this
 is
 a
 test
 

StringTokenizer is a legacy class that is retained for compatibility reasons although its use is discouraged in new code. It is recommended that anyone seeking this functionality use the split method of String or the java.util.regex package instead.

The following example illustrates how the String.split method can be used to break up a string into its basic tokens:

 String[] result = "this is a test".split("\\s");
 for (int x=0; x<result.length; x++)
 System.out.println(result[x]);
 

prints the following output:

 this
 is
 a
 test
 

If the returnDelims flag is true, then the delimiter characters are also returned as tokens. Each delimiter is returned as a string of length one. If the flag is false, the delimiter characters are skipped and only serve as separators between tokens.

Note that if delim is null, this constructor does not throw an exception. However, trying to invoke other methods on the resulting StringTokenizer may result in a NullPointerException.
Parameters:
  str - a string to be parsed.
Parameters:
  delim - the delimiters.
Parameters:
  returnDelims - flag indicating whether to return the delimitersas tokens.
exception:
  NullPointerException - if str is null

Note that if delim is null, this constructor does not throw an exception. However, trying to invoke other methods on the resulting StringTokenizer may result in a NullPointerException.
Parameters:
  str - a string to be parsed.
Parameters:
  delim - the delimiters.
exception:
  NullPointerException - if str is null