| java.lang.Object | |
| ↳ | java.io.Reader |
 Known Direct Subclasses
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Known Indirect Subclasses
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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. | |||||||||||
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. | |||||||||||
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 at most
count characters from this reader and stores them
at offset in the character array buf. | |||||||||||
Reads characters and puts them into the
target character buffer. | |||||||||||
Reads characters from this reader and stores them in the character array
buf starting at offset 0. | |||||||||||
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. | |||||||||||
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.Readable
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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. |
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| NullPointerException | if lock is null.
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Closes this reader. Implementations of this method should free any resources associated with the reader.
| IOException | if an error occurs while closing this reader. |
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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. |
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| IllegalArgumentException | if readLimit < 0. |
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| 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. |
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Reads at most count characters from this reader and stores them
at offset in the character array buf. Returns the number
of characters actually read or -1 if the end of the reader has been
reached.
| buf | the character array to store the characters read. |
|---|---|
| offset | the initial position in buffer to store the characters
read from this reader. |
| count | the maximum number of characters to read. |
| IOException | if this reader is closed or some other I/O error occurs. |
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Reads characters and puts them into the target character buffer.
| target | the destination character buffer. |
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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. |
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| NullPointerException | if target is null. |
| ReadOnlyBufferException | if target is read-only.
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Reads characters from this reader and stores them in the character array
buf starting at offset 0. Returns the number of characters
actually read or -1 if the end of the reader has been reached.
| buf | character array to store the characters read. |
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| IOException | if this reader is closed or some other I/O error occurs. |
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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. |
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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. |