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
.
Constants | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
int | TT_EOF | A constant indicating that the end of the stream has been read. | |||||||||
int | TT_EOL | A constant indicating that the end of the line has been read. | |||||||||
int | TT_NUMBER | A constant indicating that a number token has been read. | |||||||||
int | TT_WORD | A constant indicating that a word token has been read. |
Fields | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
nval | If the current token is a number, this field contains the value of that number. | ||||||||||
sval | If the current token is a word token, this field contains a string giving the characters of the word token. | ||||||||||
ttype | After a call to the nextToken method, this field
contains the type of the token just read. |
Public Constructors | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
This constructor 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); | |||||||||||
Create a tokenizer that parses the given character stream.
|
Public Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Specified that the character argument starts a single-line
comment.
| |||||||||||
Determines whether or not ends of line are treated as tokens.
| |||||||||||
Return the current line number.
| |||||||||||
Determines whether or not word token are automatically lowercased.
| |||||||||||
Parses the next token from the input stream of this tokenizer.
| |||||||||||
Specifies that the character argument is "ordinary"
in this tokenizer.
| |||||||||||
Specifies that all characters c in the range
low <= c <= high
are "ordinary" in this tokenizer. | |||||||||||
Specifies that numbers should be parsed by this tokenizer.
| |||||||||||
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. | |||||||||||
Specifies that matching pairs of this character delimit string
constants in this tokenizer.
| |||||||||||
Resets this tokenizer's syntax table so that all characters are
"ordinary." See the
ordinaryChar method
for more information on a character being ordinary. | |||||||||||
Determines whether or not the tokenizer recognizes C++-style comments.
| |||||||||||
Determines whether or not the tokenizer recognizes C-style comments.
| |||||||||||
Returns the string representation of the current stream token and
the line number it occurs on.
| |||||||||||
Specifies that all characters c in the range
low <= c <= high
are white space characters. | |||||||||||
Specifies that all characters c in the range
low <= c <= high
are word constituents. |
[Expand]
Inherited Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
From class
java.lang.Object
|
A constant indicating that the end of the stream has been read.
A constant indicating that the end of the line has been read.
A constant indicating that a number token has been read.
A constant indicating that a word token has been read.
If the current token is a word token, this field contains a string giving the characters of the word token. When the current token is a quoted string token, this field contains the body of the string.
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.
After a call to the nextToken
method, this field
contains the type of the token just read. For a single character
token, its value is the single character, converted to an integer.
For a quoted string token, its value is the quote character.
Otherwise, its value is one of the following:
TT_WORD
indicates that the token is a word.
TT_NUMBER
indicates that the token is a number.
TT_EOL
indicates that the end of line has been read.
The field can only have this value if the
eolIsSignificant
method has been called with the
argument true
.
TT_EOF
indicates that the end of the input stream
has been reached.
The initial value of this field is -4.
This constructor 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);
Creates a stream tokenizer that parses the specified input stream. The stream tokenizer is initialized to the following default state:
'A'
through 'Z'
,
'a'
through 'z'
, and
'\u00A0'
through '\u00FF'
are
considered to be alphabetic.
'\u0000'
through
'\u0020'
are considered to be white space.
'/'
is a comment character.
'\''
and double quote '"'
are string quote characters.
is | an input stream. |
---|
Create a tokenizer that parses the given character stream.
r | a Reader object providing the input stream. |
---|
Specified that the character argument starts a single-line comment. All characters from the comment character to the end of the line are ignored by this stream tokenizer.
Any other attribute settings for the specified character are cleared.
ch | the character. |
---|
Determines whether or not ends of line are treated as tokens.
If the flag argument is true, this tokenizer treats end of lines
as tokens; the nextToken
method returns
TT_EOL
and also sets the ttype
field to
this value when an end of line is read.
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.
flag | true indicates that end-of-line characters
are separate tokens; false indicates that
end-of-line characters are white space. |
---|
Return the current line number.
Determines whether or not word token are automatically lowercased.
If the flag argument is true
, then the value in the
sval
field is lowercased whenever a word token is
returned (the ttype
field has the
value TT_WORD
by the nextToken
method
of this tokenizer.
If the flag argument is false
, then the
sval
field is not modified.
fl | true indicates that all word tokens should
be lowercased. |
---|
Parses the next token from the input stream of this tokenizer.
The type of the next token is returned in the ttype
field. Additional information about the token may be in the
nval
field or the sval
field of this
tokenizer.
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.
ttype
field.IOException | if an I/O error occurs. |
---|
Specifies that the character argument is "ordinary"
in this tokenizer. It removes any special significance the
character has as a comment character, word component, string
delimiter, white space, or number character. When such a character
is encountered by the parser, the parser treats it as a
single-character token and sets ttype
field to the
character value.
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.
ch | the character. |
---|
Specifies that all characters c in the range
low <= c <= high
are "ordinary" in this tokenizer. See the
ordinaryChar
method for more information on a
character being ordinary.
low | the low end of the range. |
---|---|
hi | the high end of the range. |
Specifies that numbers should be parsed by this tokenizer. The syntax table of this tokenizer is modified so that each of the twelve characters:
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 ttype
field to the value TT_NUMBER
and putting the numeric
value of the token into the nval
field.
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.
Specifies that matching pairs of this character delimit string constants in this tokenizer.
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.
ch | the character. |
---|
Resets this tokenizer's syntax table so that all characters are
"ordinary." See the ordinaryChar
method
for more information on a character being ordinary.
Determines whether or not the tokenizer recognizes C++-style comments.
If the flag argument is true
, this stream tokenizer
recognizes C++-style comments. Any occurrence of two consecutive
slash characters ('/'
) is treated as the beginning of
a comment that extends to the end of the line.
If the flag argument is false
, then C++-style
comments are not treated specially.
flag | true indicates to recognize and ignore
C++-style comments.
|
---|
Determines whether or not the tokenizer recognizes C-style comments.
If the flag argument is true
, this stream tokenizer
recognizes C-style comments. All text between successive
occurrences of /*
and */
are discarded.
If the flag argument is false
, then C-style comments
are not treated specially.
flag | true indicates to recognize and ignore
C-style comments.
|
---|
Specifies that all characters c in the range
low <= c <= high
are white space characters. White space characters serve only to
separate tokens in the input stream.
Any other attribute settings for the characters in the specified range are cleared.
low | the low end of the range. |
---|---|
hi | the high end of the range. |
Specifies that all characters c in the range
low <= c <= high
are word constituents. A word token consists of a word constituent
followed by zero or more word constituents or number constituents.
low | the low end of the range. |
---|---|
hi | the high end of the range. |