Added in API level 1

Reader

abstract class Reader : Readable, Closeable
kotlin.Any
   ↳ java.io.Reader

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.

Summary

Protected constructors

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

Reader(lock: Any!)

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

Public methods
abstract Unit

Closes the stream and releases any system resources associated with it.

open Unit
mark(readAheadLimit: Int)

Marks the present position in the stream.

open Boolean

Tells whether this stream supports the mark() operation.

open static Reader!

Returns a new Reader that reads no characters.

open Int
read(target: CharBuffer!)

Attempts to read characters into the specified character buffer.

open Int

Reads a single character.

open Int
read(cbuf: CharArray!)

Reads characters into an array.

abstract Int
read(cbuf: CharArray!, off: Int, len: Int)

Reads characters into a portion of an array.

open Boolean

Tells whether this stream is ready to be read.

open Unit

Resets the stream.

open Long
skip(n: Long)

Skips characters.

open Long

Reads all characters from this reader and writes the characters to the given writer in the order that they are read.

Properties
Any!

The object used to synchronize operations on this stream.

Protected constructors

Reader

Added in API level 1
protected Reader()

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

Reader

Added in API level 1
protected Reader(lock: Any!)

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

Parameters
lock Any!: The Object to synchronize on.

Public methods

close

Added in API level 1
abstract fun close(): Unit

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.

Exceptions
java.lang.Exception if this resource cannot be closed
java.io.IOException if an I/O error occurs
java.io.IOException If an I/O error occurs

mark

Added in API level 1
open fun mark(readAheadLimit: Int): Unit

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 Int: 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.
Exceptions
java.io.IOException If the stream does not support mark(), or if some other I/O error occurs

markSupported

Added in API level 1
open fun markSupported(): Boolean

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

Return
Boolean true if and only if this stream supports the mark operation.

nullReader

Added in API level 33
open static fun nullReader(): Reader!

Returns a new Reader that reads no characters. The returned stream is initially open. The stream is closed by calling the close() method. Subsequent calls to close() have no effect.

While the stream is open, the read(), read(char[]), read(char[], int, int), read(Charbuffer), ready(), skip(long), and transferTo() methods all behave as if end of stream has been reached. After the stream has been closed, these methods all throw IOException.

The markSupported() method returns false. The mark() and reset() methods throw an IOException.

The object used to synchronize operations on the returned Reader is not specified.

Return
Reader! a Reader which reads no characters

read

Added in API level 1
open fun read(target: CharBuffer!): Int

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
cb the buffer to read characters into
target CharBuffer!: the buffer to read characters into
Return
Int The number of characters added to the buffer, or -1 if this source of characters is at its end
Exceptions
java.io.IOException if an I/O error occurs
java.lang.NullPointerException if target is null
java.nio.ReadOnlyBufferException if target is a read only buffer

read

Added in API level 1
open fun read(): Int

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.

Return
Int 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
Exceptions
java.io.IOException If an I/O error occurs

read

Added in API level 1
open fun read(cbuf: CharArray!): Int

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 CharArray!: Destination buffer
Return
Int The number of characters read, or -1 if the end of the stream has been reached
Exceptions
java.io.IOException If an I/O error occurs

read

Added in API level 1
abstract fun read(
    cbuf: CharArray!,
    off: Int,
    len: Int
): Int

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 CharArray!: Destination buffer
off Int: Offset at which to start storing characters
len Int: Maximum number of characters to read
Return
Int The number of characters read, or -1 if the end of the stream has been reached
Exceptions
java.io.IOException If an I/O error occurs
java.lang.IndexOutOfBoundsException If off is negative, or len is negative, or len is greater than cbuf.length - off

ready

Added in API level 1
open fun ready(): Boolean

Tells whether this stream is ready to be read.

Return
Boolean 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.
Exceptions
java.io.IOException If an I/O error occurs

reset

Added in API level 1
open fun reset(): Unit

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().

Exceptions
java.io.IOException 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

skip

Added in API level 1
open fun skip(n: Long): Long

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 Long: The number of characters to skip
Return
Long The number of characters actually skipped
Exceptions
java.lang.IllegalArgumentException If n is negative.
java.io.IOException If an I/O error occurs

transferTo

Added in API level 33
open fun transferTo(out: Writer!): Long

Reads all characters from this reader and writes the characters to the given writer in the order that they are read. On return, this reader will be at end of the stream. This method does not close either reader or writer.

This method may block indefinitely reading from the reader, or writing to the writer. The behavior for the case where the reader and/or writer is asynchronously closed, or the thread interrupted during the transfer, is highly reader and writer specific, and therefore not specified.

If an I/O error occurs reading from the reader or writing to the writer, then it may do so after some characters have been read or written. Consequently the reader may not be at end of the stream and one, or both, streams may be in an inconsistent state. It is strongly recommended that both streams be promptly closed if an I/O error occurs.

Parameters
out Writer!: the writer, non-null
Return
Long the number of characters transferred
Exceptions
java.io.IOException if an I/O error occurs when reading or writing
java.lang.NullPointerException if out is null

Properties

lock

Added in API level 1
protected var lock: Any!

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.