StringTokenizer

public class StringTokenizer extends Object
implements Enumeration<Object>

The string tokenizer class allows an application to break a string into tokens. The tokenization method is much simpler than the one used by the StreamTokenizer class. The StringTokenizer methods do not distinguish among identifiers, numbers, and quoted strings, nor do they recognize and skip comments.

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
 

See Also

Public Constructor Summary

StringTokenizer(String str, String delim, boolean returnDelims)
Constructs a string tokenizer for the specified string.
StringTokenizer(String str, String delim)
Constructs a string tokenizer for the specified string.
StringTokenizer(String str)
Constructs a string tokenizer for the specified string.

Public Method Summary

int
countTokens()
Calculates the number of times that this tokenizer's nextToken method can be called before it generates an exception.
boolean
hasMoreElements()
Returns the same value as the hasMoreTokens method.
boolean
hasMoreTokens()
Tests if there are more tokens available from this tokenizer's string.
Object
nextElement()
Returns the same value as the nextToken method, except that its declared return value is Object rather than String.
String
nextToken(String delim)
Returns the next token in this string tokenizer's string.
String
nextToken()
Returns the next token from this string tokenizer.

Inherited Method Summary

Public Constructors

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 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.
delim the delimiters.
returnDelims flag indicating whether to return the delimiters as tokens.
Throws
NullPointerException if str is null

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.

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.
delim the delimiters.
Throws
NullPointerException if str is null

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

Public Methods

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

public boolean hasMoreElements ()

Returns the same value as the hasMoreTokens method. It exists so that this class can implement the Enumeration interface.

Returns
  • true if there are more tokens; false otherwise.

public boolean