 |
Chapter 11 The java.io Package |
 |
|
Chapter 11 The java.io Package |
|
java.io.StreamTokenizer
java.lang.Object
None
None
JDK 1.0 or later
The StreamTokenizer class performs a lexical analysis on an InputStream object and breaks the stream into tokens. Although StreamTokenizer is not a general-purpose parser, it recognizes tokens that are similar to those used in the Java language. A StreamTokenizer recognizes identifiers, numbers, quoted strings, and various comment styles.
A StreamTokenizer object can be wrapped around an InputStream. In this case, when the StreamTokenizer reads bytes from the stream, the bytes are converted to Unicode characters by simply zero-extending the byte values to 16 bits. As of Java 1.1, a StreamTokenizer can be wrapped around a Reader to eliminate this problem.
The nextToken() method returns the next token from the stream. The rest of the methods in StreamTokenizer control how the object interprets the characters that it reads and tokenizes them.
The parsing functionality of StreamTokenizer is controlled by a table and a number of flags. Each character that is read from the InputStream is in the range '\u0000' to '\uFFFF'. The character value looks up attributes of the character in the table. A character can have zero or more of the following attributes: whitespace, alphabetic, numeric, string quote, and comment character.
By default, a StreamTokenizer recognizes the following:
public class java.io.StreamTokenizer extends java.lang.Object {
// Variables
public double nval;
public String sval;
public int ttype;
public final static int TT_EOF;
public final static int TT_EOL;
public final static int TT_NUMBER;
public final static int TT_WORD;
// Constructors
public StreamTokenizer(InputStream in); // Deprecated in 1.1
public StreamTokenizer(Reader in); // New in 1.1
// Instance Methods
public void commentChar(int ch);
public void eolIsSignificant(boolean flag);
public int lineno();
public void lowerCaseMode(boolean flag);
public int nextToken();
public void ordinaryChar(int ch);
public void ordinaryChars(int low, int hi);
public void parseNumbers();
public void pushBack();
public void quoteChar(int ch);
public void resetSyntax();
public void slashSlashComments(boolean flag);
public void slashStarComments(boolean flag);
public String toString();
public void whitespaceChars(int low, int hi);
public void wordChars(int low, int hi);
}
This variable contains the value of a TT_NUMBER token.
This variable contains the value of a TT_WORD token.
This variable indicates the token type. The value is either one of the TT_ constants defined below or the character that has just been parsed from the input stream.
This token type indicates that the end of the stream has been reached.
This token type indicates that the end of a line has been reached. The value is not returned by nextToken() unless eolIsSignificant(true) has been called.
This token type indicates that a number has been parsed. The number is placed in nval.
This token type indicates that a word has been parsed. The word is placed in sval.
Deprecated as of JDK 1.1
The input stream to tokenize.
This constructor creates a StreamTokenizer that reads from the given InputStream. As of JDK 1.1, this method is deprecated and StreamTokenizer(Reader) should be used instead.
New as of JDK 1.1
The reader to tokenize.
This constructor creates a StreamTokenizer that reads from the given Reader.
The character to use to indicate comments.
This method tells this StreamTokenizer to treat the given character as the beginning of a comment that ends at the end of the line. The StreamTokenizer ignores all of the characters from the comment character to the end of the line. By default, a StreamTokenizer treats the '/' character as a comment character. This method may be called multiple times if there are multiple characters that begin comment lines.
To specify that a character is not a comment character, use ordinaryChar().
A boolean value that specifies whether or not this StreamTokenizer returns TT_EOL tokens.
A StreamTokenizer recognizes "\n", "\r", and "\r\n" as the end of a line. By default, end-of-line characters are treated as whitespace and thus, the StreamTokenizer does not return TT_EOL tokens from nextToken(). Call eolIsSignificant(true) to tell the StreamTokenizer to return TT_EOL tokens.
The current line number.
This method returns the current line number. Line numbers begin at 1.
A boolean value that specifies whether or not this StreamTokenizer returns TT_WORD tokens in lowercase.
By default, a StreamTokenizer does not change the case of the words that it parses. However if you call lowerCaseMode(true), whenever nextToken() returns a TT_WORD token, the word in sval is converted to lowercase.
One of the token types (TT_EOF, TT_EOL, TT_NUMBER, or TT_WORD) or a character code.
If any kind of I/O error occurs.
This method reads the next token from the stream. The value returned is the same as the value of the variable ttype. The nextToken() method parses the following tokens:
The end of the input stream has been reached.
The end of a line has been reached. The eolIsSignificant() method controls whether end-of-line characters are treated as whitespace or returned as TT_EOL tokens.
A number has been parsed. The value can be found in the variable nval. The parseNumbers() method tells the StreamTokenizer to recognize numbers distinct from words.
A word has been parsed. The word can be found in the variable sval.
A quoted string has been parsed. The variable ttype is set to the quote character, and sval contains the string itself. You can tell the StreamTokenizer what characters to use as quote characters using quoteChar().
A single character has been parsed. The variable ttype is set to the character value.
The character to treat normally.
This method causes this StreamTokenizer to treat the given character as an ordinary character. This means that the character has no special significance as a comment, string quote, alphabetic, numeric, or whitespace character. For example, to tell the StreamTokenizer that the slash does not start a single-line comment, use ordinaryChar('/').
The beginning of a range of character values.
The end of a range of character values.
This method tells this StreamTokenizer to treat all of the characters in the given range as ordinary characters. See the description of ordinaryChar() above for more information.
This method tells this StreamTokenizer to recognize numbers. The StreamTokenizer constructor calls this method, so the default behavior of a StreamTokenizer is to recognize numbers. This method modifies the syntax table of the StreamTokenizer so that the following characters have the numeric attribute: '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '.', and '-'
When the parser encounters a token that has the format of a double-precision floating-point number, the token is treated as a number rather than a word. The ttype variable is set to TT_NUMBER, and nval is set to the value of the number.
To use a StreamTokenizer that does not parse numbers, make the above characters ordinary using ordinaryChar() or ordinaryChars():
This method has the effect of pushing the current token back onto the stream. In other words, after a call to this method, the next call to the nextToken() method returns the same result as the previous call to the nextToken()method without reading any input.
The character to use as a delimiter for quoted strings.
This method tells this StreamTokenizer to treat the given character as the beginning or end of a quoted string. By default, the single-quote character and the double-quote character are string-quote characters. When the parser encounters a string-quote character, the ttype variable is set to the quote character, and sval is set to the actual string. The string consists of all the characters after (but not including) the string-quote character up to (but not including) the next occurrence of the same string-quote character, a line terminator, or the end of the stream.
To specify that a character is not a string-quote character, use ordinaryChar().
This method resets this StreamTokenizer, which causes it to treat all characters as ordinary characters. See the description of ordinaryChar() above for more information.
A boolean value that specifies whether or not this StreamTokenizer recognizes double-slash comments (//).
By default, a StreamTokenizer does not recognize double-slash comments. However, if you call slashSlashComments(true), the nextToken() method recognizes and ignores double-slash comments.
A boolean value that specifies whether or not this StreamTokenizer recognizes slash-star (/* ... */) comments.
By default, a StreamTokenizer does not recognize slash-star comments. However, if you call slashStarComments(true), the nextToken() method recognizes and ignores slash-star comments.
A String representation of the current token.
Object.toString()
This method returns a string representation of the current token recognized by the nextToken() method. This string representation consists of the value of ttype, the value of sval if the token is a word or the value of nval if the token is a number, and the current line number.
The beginning of a range of character values.
The end of a range of character values.
This method causes this StreamTokenizer to treat characters in the specified range as whitespace. The only function of whitespace characters is to separate tokens in the stream.
The beginning of a range of character values.
The end of a range of character values.
This method causes this StreamTokenizer to treat characters in the specified range as characters that are part of a word token, or, in other words, consider the characters to be alphabetic. A word token consists of a sequence of characters that begins with an alphabetic character and is followed by zero or more numeric or alphabetic characters.
|
Method |
Inherited From |
Method |
Inherited From |
|---|---|---|---|
|
clone() |
Object |
equals(Object) |
Object |
|
finalize() |
Object |
getClass() |
Object |
|
hashCode() |
Object |
notify() |
Object |
|
notifyAll() |
Object |
wait() |
Object |
|
wait(long) |
Object |
wait(long, int) |
Object |
InputStream, IOException, Reader, StringTokenizer
|
 |
|
| StreamCorruptedException |  |
StringBufferInputStream |
| This HTML Help has been published using the chm2web software. |