java.lang.Object | |
↳ | java.io.Reader |
Known Direct Subclasses |
Known Indirect Subclasses |
The base class for all readers. A reader is a means of reading data from a source in a character-wise manner. Some readers also support marking a position in the input and returning to this position later.
This abstract class does not provide a fully working implementation, so it
needs to be subclassed, and at least the
read(char[], int, int)
and
close()
methods needs to be overridden. Overriding some of the
non-abstract methods is also often advised, since it might result in higher
efficiency.
Many specialized readers for purposes like reading from a file already exist in this package.
Fields | |||||||||||
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lock | The object used to synchronize access to the reader. |
Protected Constructors | |||||||||||
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Constructs a new
Reader
with
this
as the object used to
synchronize critical sections.
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Constructs a new
Reader
with
lock
used to synchronize
critical sections.
|
Public Methods | |||||||||||
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Closes this reader.
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Sets a mark position in this reader.
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Indicates whether this reader supports the
mark()
and
reset()
methods.
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Reads a single character from this reader and returns it as an integer
with the two higher-order bytes set to 0.
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Reads up to
count
characters from this reader and stores them
at
offset
in the character array
buffer
.
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|
Reads characters and puts them into the
target
character buffer.
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Reads characters from this reader and stores them in the character array
buffer
starting at offset 0.
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Indicates whether this reader is ready to be read without blocking.
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Resets this reader's position to the last
mark()
location.
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Skips
charCount
characters in this reader.
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[Expand]
Inherited Methods
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From class
java.lang.Object
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From interface
java.io.Closeable
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From interface
java.lang.AutoCloseable
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From interface
java.lang.Readable
|
Constructs a new
Reader
with
this
as the object used to
synchronize critical sections.
Constructs a new
Reader
with
lock
used to synchronize
critical sections.
lock |
the
Object
used to synchronize critical sections.
|
---|
NullPointerException |
if
lock
is
null
.
|
---|
Closes this reader. Implementations of this method should free any resources associated with the reader.
IOException | if an error occurs while closing this reader. |
---|
Sets a mark position in this reader. The parameter
readLimit
indicates how many characters can be read before the mark is invalidated.
Calling
reset()
will reposition the reader back to the marked
position if
readLimit
has not been surpassed.
This default implementation simply throws an
IOException
;
subclasses must provide their own implementation.
readLimit | the number of characters that can be read before the mark is invalidated. |
---|
IllegalArgumentException |
if
readLimit < 0
.
|
---|---|
IOException | if an error occurs while setting a mark in this reader. |
Indicates whether this reader supports the
mark()
and
reset()
methods. This default implementation returns
false
.
false
.
Reads a single character from this reader and returns it as an integer with the two higher-order bytes set to 0. Returns -1 if the end of the reader has been reached.
IOException | if this reader is closed or some other I/O error occurs. |
---|
Reads up to
count
characters from this reader and stores them
at
offset
in the character array
buffer
. Returns the number
of characters actually read or -1 if the end of the reader has been
reached.
IOException | if this reader is closed or some other I/O error occurs. |
---|
Reads characters and puts them into the
target
character buffer.
target | the destination character buffer. |
---|
target
or -1 if the end
of this reader has been reached before a character has been read.
IOException | if any I/O error occurs while reading from this reader. |
---|---|
NullPointerException |
if
target
is
null
.
|
ReadOnlyBufferException |
if
target
is read-only.
|
Reads characters from this reader and stores them in the character array
buffer
starting at offset 0. Returns the number of characters
actually read or -1 if the end of the reader has been reached.
IOException | if this reader is closed or some other I/O error occurs. |
---|
Indicates whether this reader is ready to be read without blocking.
Returns
true
if this reader will not block when
read
is
called,
false
if unknown or blocking will occur. This default
implementation always returns
false
.
false
.
IOException | if this reader is closed or some other I/O error occurs. |
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Resets this reader's position to the last
mark()
location.
Invocations of
read()
and
skip()
will occur from this new
location. If this reader has not been marked, the behavior of
reset()
is implementation specific. This default
implementation throws an
IOException
.
IOException | always thrown in this default implementation. |
---|
Skips
charCount
characters in this reader. Subsequent calls of
read
methods will not return these characters unless
reset
is used. This method may perform multiple reads to read
charCount
characters.
IllegalArgumentException |
if
charCount < 0
.
|
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IOException | if this reader is closed or some other I/O error occurs. |