Class: java.util.StringTokenizer
- public class StringTokenizer
- 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
Methods
-
StringTokenizertop
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. -
StringTokenizertop
Constructs a string tokenizer for the specified string. The characters in thedelimargument 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.
-
StringTokenizertop
Constructs a string tokenizer for the specified string. All characters in thedelimargument are the delimiters for separating tokens.If the
returnDelimsflag istrue, then the delimiter characters are also returned as tokens. Each delimiter is returned as a string of length one. If the flag isfalse, 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.
-
countTokenstop
public int countTokens()Calculates the number of times that this tokenizer'snextTokenmethod can be called before it generates an exception. The current position is not advanced. -
hasMoreElementstop
public boolean hasMoreElements()Returns the same value as thehasMoreTokensmethod. It exists so that this class can implement theEnumerationinterface.- Specified by:
- hasMoreElements from Enumeration<Object>
-
hasMoreTokenstop
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. -
nextElementtop
public Object nextElement()Returns the same value as thenextTokenmethod, except that its declared return value isObjectrather thanString. It exists so that this class can implement theEnumerationinterface.- Specified by:
- nextElement from Enumeration<Object>
-
nextTokentop
public String nextToken()Returns the next token from this string tokenizer. -
nextTokentop
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.