Class java.util.StringTokenizer - JDK 5 Documentation v1.1.8, Java 2 SDK 英文文档

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Class java.util.StringTokenizer

java.lang.Object
   |
   +----java.util.StringTokenizer

public class StringTokenizer
extends Object
implements Enumeration

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 returnTokens 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 considered to be tokens. A token is either one delimiter character, or a maximal sequence of consecutive characters that are not delimiters.

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

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

prints the following output:

     this
     is
     a
     test

See Also:: StreamTokenizer

StringTokenizer(String): Constructs a string tokenizer for the specified string.
StringTokenizer(String, String): Constructs a string tokenizer for the specified string.
StringTokenizer(String, String, boolean): Constructs a string tokenizer for the specified string.

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

StringTokenizer

 public StringTokenizer(String str,
                        String delim,
                        boolean returnTokens)

Constructs a string tokenizer for the specified string. The characters in the delim argument are the delimiters for separating tokens.

If the returnTokens 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.

Parameters:: str - a string to be parsed.; delim - the delimiters.; returnTokens - flag indicating whether to return the delimiters as tokens.

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.

Parameters:: str - a string to be parsed.; delim - the delimiters.

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": the space character, the tab character, the newline character, and the carriage-return character.

Parameters:: str - a string to be parsed.

hasMoreTokens

 public boolean hasMoreTokens()

Tests if there are more tokens available from this tokenizer's string.

Returns:: true if there are more tokens available from this tokenizer's string; 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. 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.

Returns:: true if there are more tokens; false otherwise.
See Also:: Enumeration, hasMoreTokens

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.

Returns:: the next token in the string.
Throws: NoSuchElementException: if there are no more tokens in this tokenizer's string.
See Also:: Enumeration, nextToken

countTokens

 public int countTokens()

Calculates the number of times that this tokenizer's nextToken method can be called before it generates an exception.

Returns:: the number of tokens remaining in the string using the current delimiter set.
See Also:: nextToken

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