java.lang.Object java.io.StreamTokenizer
The StreamTokenizer class takes an input stream and parses it into "tokens", allowing the tokens to be read one at a time. The parsing process is controlled by a table and a number of flags that can be set to various states. The stream tokenizer can recognize identifiers, numbers, quoted strings, and various comment styles.
Each byte read from the input stream is regarded as a character in the range '\u0000' through '\u00FF'. The character value is used to look up five possible attributes of the character: white space , alphabetic , numeric , string quote , and comment character . Each character can have zero or more of these attributes.
In addition, an instance has four flags. These flags indicate:
A typical application first constructs an instance of this class, sets up the syntax tables, and then repeatedly loops calling the nextToken method in each iteration of the loop until it returns the value TT_EOF.
Field Summary | |
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double |
nval
If the current token is a number, this field contains the value of that number. |
String |
sval
If the current token is a word token, this field contains a string giving the characters of the word token. |
static int |
TT_EOF
A constant indicating that the end of the stream has been read. |
static int |
TT_EOL
A constant indicating that the end of the line has been read. |
static int |
TT_NUMBER
A constant indicating that a number token has been read. |
static int |
TT_WORD
A constant indicating that a word token has been read. |
int |
ttype
After a call to the nextToken method, this field contains the type of the token just read. |
Constructor Summary | |
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StreamTokenizer
(
InputStream
is) Deprecated. As of JDK version 1.1, the preferred way to tokenize an input stream is to convert it into a character stream, for example: Reader r = new BufferedReader(new InputStreamReader(is)); StreamTokenizer st = new StreamTokenizer(r); |
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StreamTokenizer
(
Reader
r) Create a tokenizer that parses the given character stream. |
Method Summary | |
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void |
commentChar
(int ch) Specified that the character argument starts a single-line comment. |
void |
eolIsSignificant
(boolean flag) Determines whether or not ends of line are treated as tokens. |
int |
lineno
() Return the current line number. |
void |
lowerCaseMode
(boolean fl) Determines whether or not word token are automatically lowercased. |
int |
nextToken
() Parses the next token from the input stream of this tokenizer. |
void |
ordinaryChar
(int ch) Specifies that the character argument is "ordinary" in this tokenizer. |
void |
ordinaryChars
(int low, int hi) Specifies that all characters c in the range low <= c <= high are "ordinary" in this tokenizer. |
void |
parseNumbers
() Specifies that numbers should be parsed by this tokenizer. |
void |
pushBack
() Causes the next call to the nextToken method of this tokenizer to return the current value in the ttype field, and not to modify the value in the nval or sval field. |
void |
quoteChar
(int ch) Specifies that matching pairs of this character delimit string constants in this tokenizer. |
void |
resetSyntax
() Resets this tokenizer's syntax table so that all characters are "ordinary." See the ordinaryChar method for more information on a character being ordinary. |
void |
slashSlashComments
(boolean flag) Determines whether or not the tokenizer recognizes C++-style comments. |
void |
slashStarComments
(boolean flag) Determines whether or not the tokenizer recognizes C-style comments. |
String |
toString
() Returns the string representation of the current stream token and the line number it occurs on. |
void |
whitespaceChars
(int low, int hi) Specifies that all characters c in the range low <= c <= high are white space characters. |
void |
wordChars
(int low, int hi) Specifies that all characters c in the range low <= c <= high are word constituents. |
Methods inherited from class java.lang. Object |
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clone , equals , finalize , getClass , hashCode , notify , notifyAll , wait , wait , wait |
Field Detail |
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public int ttype
The initial value of this field is -4.
public static final int TT_EOF
public static final int TT_EOL
public static final int TT_NUMBER
public static final int TT_WORD
public String sval
The current token is a word when the value of the ttype field is TT_WORD. The current token is a quoted string token when the value of the ttype field is a quote character.
The initial value of this field is null.
public double nval
The initial value of this field is 0.0.
Constructor Detail |
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public StreamTokenizer(InputStream is)
Reader r = new BufferedReader(new InputStreamReader(is)); StreamTokenizer st = new StreamTokenizer(r);
public StreamTokenizer(Reader r)
Method Detail |
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public void resetSyntax()
public void wordChars(int low, int hi)
public void whitespaceChars(int low, int hi)
Any other attribute settings for the characters in the specified range are cleared.
public void ordinaryChars(int low, int hi)
public void ordinaryChar(int ch)
Making a line terminator character "ordinary" may interfere with the ability of a StreamTokenizer to count lines. The lineno method may no longer reflect the presence of such terminator characters in its line count.
public void commentChar(int ch)
Any other attribute settings for the specified character are cleared.
public void quoteChar(int ch)
When the nextToken method encounters a string constant, the ttype field is set to the string delimiter and the sval field is set to the body of the string.
If a string quote character is encountered, then a string is recognized, consisting of all characters after (but not including) the string quote character, up to (but not including) the next occurrence of that same string quote character, or a line terminator, or end of file. The usual escape sequences such as "\n" and "\t" are recognized and converted to single characters as the string is parsed.
Any other attribute settings for the specified character are cleared.
public void parseNumbers()
0 1 2 3 4 5 6 7 8 9 . -
has the "numeric" attribute.
When the parser encounters a word token that has the format of a double precision floating-point number, it treats the token as a number rather than a word, by setting the the ttype field to the value TT_NUMBER and putting the numeric value of the token into the nval field.
public void eolIsSignificant(boolean flag)
A line is a sequence of characters ending with either a carriage-return character ('\r') or a newline character ('\n'). In addition, a carriage-return character followed immediately by a newline character is treated as a single end-of-line token.
If the flag is false, end-of-line characters are treated as white space and serve only to separate tokens.
public void slashStarComments(boolean flag)
If the flag argument is false, then C-style comments are not treated specially.
public void slashSlashComments(boolean flag)
If the flag argument is false, then C++-style comments are not treated specially.
public void lowerCaseMode(boolean fl)
If the flag argument is false, then the sval field is not modified.
public int nextToken() throws IOException
Typical clients of this class first set up the syntax tables and then sit in a loop calling nextToken to parse successive tokens until TT_EOF is returned.
public void pushBack()
public int lineno()
public String toString()
The precise string returned is unspecified, although the following example can be considered typical:
Token['a'], line 10