# Reader

public abstract class **Reader** extends [Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html)  
implements [Readable](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Readable.html) [Closeable](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/Closeable.html)

|---|---|---|
| Known Direct Subclasses [BufferedReader](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/BufferedReader.html), [CharArrayReader](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/CharArrayReader.html), [FilterReader](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/FilterReader.html), [InputStreamReader](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/InputStreamReader.html), [PipedReader](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/PipedReader.html), [StringReader](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/StringReader.html) |---|---| | [BufferedReader](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/BufferedReader.html) | Reads text from a character-input stream, buffering characters so as to provide for the efficient reading of characters, arrays, and lines. | | [CharArrayReader](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/CharArrayReader.html) | This class implements a character buffer that can be used as a character-input stream. | | [FilterReader](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/FilterReader.html) | Abstract class for reading filtered character streams. | | [InputStreamReader](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/InputStreamReader.html) | An InputStreamReader is a bridge from byte streams to character streams: It reads bytes and decodes them into characters using a specified `https://developers.google.com/j2objc/javadoc/jre/reference/java/nio/charset/Charset.html`. | | [PipedReader](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/PipedReader.html) | Piped character-input streams. | | [StringReader](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/StringReader.html) | A character stream whose source is a string. | |||

|---|---|---|
| Known Indirect Subclasses [FileReader](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/FileReader.html), [LineNumberReader](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/LineNumberReader.html), [PushbackReader](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/PushbackReader.html) |---|---| | [FileReader](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/FileReader.html) | Convenience class for reading character files. | | [LineNumberReader](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/LineNumberReader.html) | A buffered character-input stream that keeps track of line numbers. | | [PushbackReader](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/PushbackReader.html) | A character-stream reader that allows characters to be pushed back into the stream. | |||

Abstract class for reading character streams. The only methods that a
subclass must implement are read(char\[\], int, int) and close(). Most
subclasses, however, will override some of the methods defined here in order
to provide higher efficiency, additional functionality, or both.

##### See Also

- `https://developers.google.com/j2objc/javadoc/jre/reference/java/io/BufferedReader.html`
- `https://developers.google.com/j2objc/javadoc/jre/reference/java/io/LineNumberReader.html`
- `https://developers.google.com/j2objc/javadoc/jre/reference/java/io/CharArrayReader.html`
- `https://developers.google.com/j2objc/javadoc/jre/reference/java/io/InputStreamReader.html`
- `https://developers.google.com/j2objc/javadoc/jre/reference/java/io/FileReader.html`
- `https://developers.google.com/j2objc/javadoc/jre/reference/java/io/FilterReader.html`
- `https://developers.google.com/j2objc/javadoc/jre/reference/java/io/PushbackReader.html`
- `https://developers.google.com/j2objc/javadoc/jre/reference/java/io/PipedReader.html`
- `https://developers.google.com/j2objc/javadoc/jre/reference/java/io/StringReader.html`
- `https://developers.google.com/j2objc/javadoc/jre/reference/java/io/Writer.html`

### Field Summary

|---|---|---|
| protected [Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) | [lock](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/Reader.html#lock) | The object used to synchronize operations on this stream. |

### Protected Constructor Summary

|---|---|
|   | [Reader](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/Reader.html#Reader())() Creates a new character-stream reader whose critical sections will synchronize on the reader itself. |
|   | [Reader](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/Reader.html#Reader(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) lock) Creates a new character-stream reader whose critical sections will synchronize on the given object. |

### Public Method Summary

|---|---|
| abstract void | [close](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/Reader.html#close())() Closes the stream and releases any system resources associated with it. |
| void | [mark](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/Reader.html#mark(int))(int readAheadLimit) Marks the present position in the stream. |
| boolean | [markSupported](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/Reader.html#markSupported())() Tells whether this stream supports the mark() operation. |
| int | [read](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/Reader.html#read())() Reads a single character. |
| abstract int | [read](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/Reader.html#read(char[],%20int,%20int))(char\[\] cbuf, int off, int len) Reads characters into a portion of an array. |
| int | [read](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/Reader.html#read(char[]))(char\[\] cbuf) Reads characters into an array. |
| int | [read](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/Reader.html#read(java.nio.CharBuffer))([CharBuffer](https://developers.google.com/j2objc/javadoc/jre/reference/java/nio/CharBuffer.html) target) Attempts to read characters into the specified character buffer. |
| boolean | [ready](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/Reader.html#ready())() Tells whether this stream is ready to be read. |
| void | [reset](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/Reader.html#reset())() Resets the stream. |
| long | [skip](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/Reader.html#skip(long))(long n) Skips characters. |

### Inherited Method Summary

From class [java.lang.Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html)

|---|---|
| [Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) | [clone](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#clone())() Creates and returns a copy of this `Object`. |
| boolean | [equals](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#equals(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) obj) Compares this instance with the specified object and indicates if they are equal. |
| void | [finalize](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#finalize())() Invoked when the garbage collector has detected that this instance is no longer reachable. |
| final [Class](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Class.html)\<?\> | [getClass](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#getClass())() Returns the unique instance of `https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Class.html` that represents this object's class. |
| int | [hashCode](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#hashCode())() Returns an integer hash code for this object. |
| final void | [notify](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#notify())() Causes a thread which is waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up. |
| final void | [notifyAll](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#notifyAll())() Causes all threads which are waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up. |
| [String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) | [toString](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#toString())() Returns a string containing a concise, human-readable description of this object. |
| final void | [wait](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#wait(long,%20int))(long timeout, int nanos) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires. |
| final void | [wait](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#wait(long))(long timeout) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires. |
| final void | [wait](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#wait())() Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object. |

From interface [java.lang.Readable](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Readable.html)

|---|---|
| abstract int | [read](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Readable.html#read(java.nio.CharBuffer))([CharBuffer](https://developers.google.com/j2objc/javadoc/jre/reference/java/nio/CharBuffer.html) cb) Attempts to read characters into the specified character buffer. |

From interface [java.io.Closeable](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/Closeable.html)

|---|---|
| abstract void | [close](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/Closeable.html#close())() Closes this stream and releases any system resources associated with it. |

From interface [java.lang.AutoCloseable](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/AutoCloseable.html)

|---|---|
| abstract void | [close](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/AutoCloseable.html#close())() Closes this resource, relinquishing any underlying resources. |

## Fields

#### protected [Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html)
**lock**

The object used to synchronize operations on this stream. For
efficiency, a character-stream object may use an object other than
itself to protect critical sections. A subclass should therefore use
the object in this field rather than this or a synchronized
method.

## Protected Constructors

#### protected
**Reader**
()

Creates a new character-stream reader whose critical sections will
synchronize on the reader itself.

#### protected
**Reader**
([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) lock)

Creates a new character-stream reader whose critical sections will
synchronize on the given object.

##### Parameters

| lock | The Object to synchronize on. |
|---|---|

## Public Methods

#### public abstract void
**close**
()

Closes the stream and releases any system resources associated with
it. Once the stream has been closed, further read(), ready(),
mark(), reset(), or skip() invocations will throw an IOException.
Closing a previously closed stream has no effect.

##### Throws

| [IOException](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/IOException.html) | If an I/O error occurs |
|---|---|

#### public void
**mark**
(int readAheadLimit)

Marks the present position in the stream. Subsequent calls to reset()
will attempt to reposition the stream to this point. Not all
character-input streams support the mark() operation.

##### Parameters

| readAheadLimit | Limit on the number of characters that may be read while still preserving the mark. After reading this many characters, attempting to reset the stream may fail. |
|---|---|

##### Throws

| [IOException](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/IOException.html) | If the stream does not support mark(), or if some other I/O error occurs |
|---|---|

#### public boolean
**markSupported**
()

Tells whether this stream supports the mark() operation. The default
implementation always returns false. Subclasses should override this
method.

##### Returns

- true if and only if this stream supports the mark operation.

#### public int
**read**
()

Reads a single character. This method will block until a character is
available, an I/O error occurs, or the end of the stream is reached.

Subclasses that intend to support efficient single-character input
should override this method.

##### Returns

- The character read, as an integer in the range 0 to 65535 (0x00-0xffff), or -1 if the end of the stream has been reached

##### Throws

| [IOException](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/IOException.html) | If an I/O error occurs |
|---|---|

#### public abstract int
**read**
(char\[\] cbuf, int off, int len)

Reads characters into a portion of an array. This method will block
until some input is available, an I/O error occurs, or the end of the
stream is reached.

##### Parameters

| cbuf | Destination buffer |
| off | Offset at which to start storing characters |
| len | Maximum number of characters to read |
|---|---|

##### Returns

- The number of characters read, or -1 if the end of the stream has been reached

##### Throws

| [IOException](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/IOException.html) | If an I/O error occurs |
|---|---|

#### public int
**read**
(char\[\] cbuf)

Reads characters into an array. This method will block until some input
is available, an I/O error occurs, or the end of the stream is reached.

##### Parameters

| cbuf | Destination buffer |
|---|---|

##### Returns

- The number of characters read, or -1 if the end of the stream has been reached

##### Throws

| [IOException](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/IOException.html) | If an I/O error occurs |
|---|---|

#### public int
**read**
([CharBuffer](https://developers.google.com/j2objc/javadoc/jre/reference/java/nio/CharBuffer.html) target)

Attempts to read characters into the specified character buffer.
The buffer is used as a repository of characters as-is: the only
changes made are the results of a put operation. No flipping or
rewinding of the buffer is performed.

##### Parameters

| target | the buffer to read characters into |
|---|---|

##### Returns

- The number of characters added to the buffer, or -1 if this source of characters is at its end

##### Throws

| [IOException](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/IOException.html) | if an I/O error occurs |
| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if target is null |
| [ReadOnlyBufferException](https://developers.google.com/j2objc/javadoc/jre/reference/java/nio/ReadOnlyBufferException.html) | if target is a read only buffer |
|---|---|

#### public boolean
**ready**
()

Tells whether this stream is ready to be read.

##### Returns

- True if the next read() is guaranteed not to block for input, false otherwise. Note that returning false does not guarantee that the next read will block.

##### Throws

| [IOException](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/IOException.html) | If an I/O error occurs |
|---|---|

#### public void
**reset**
()

Resets the stream. If the stream has been marked, then attempt to
reposition it at the mark. If the stream has not been marked, then
attempt to reset it in some way appropriate to the particular stream,
for example by repositioning it to its starting point. Not all
character-input streams support the reset() operation, and some support
reset() without supporting mark().

##### Throws

| [IOException](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/IOException.html) | If the stream has not been marked, or if the mark has been invalidated, or if the stream does not support reset(), or if some other I/O error occurs |
|---|---|

#### public long
**skip**
(long n)

Skips characters. This method will block until some characters are
available, an I/O error occurs, or the end of the stream is reached.

##### Parameters

| n | The number of characters to skip |
|---|---|

##### Returns

- The number of characters actually skipped

##### Throws

| [IllegalArgumentException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/IllegalArgumentException.html) | If `n` is negative. |
| [IOException](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/IOException.html) | If an I/O error occurs |
|---|---|