# FilterReader Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels) # FilterReader ``` abstract class FilterReader : Reader ``` |---|---|----------------------------------------------------------------------------------------------| | [kotlin.Any](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-any/index.html) ||| | ↳ | [java.io.Reader](https://developer.android.com/reference/kotlin/java/io/Reader) || | | ↳ | [java.io.FilterReader](https://developer.android.com/reference/kotlin/java/io/FilterReader#) | |-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | Known Direct Subclasses [PushbackReader](https://developer.android.com/reference/kotlin/java/io/PushbackReader) |-----------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------| | [PushbackReader](https://developer.android.com/reference/kotlin/java/io/PushbackReader) | A character-stream reader that allows characters to be pushed back into the stream. | | Abstract class for reading filtered character streams. The abstract class`FilterReader`itself provides default methods that pass all requests to the contained stream. Subclasses of`FilterReader`should override some of these methods and may also provide additional methods and fields. ## Summary | Protected constructors || |-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---| | [FilterReader](https://developer.android.com/reference/kotlin/java/io/FilterReader#FilterReader(java.io.Reader))`(`in:` `[Reader](https://developer.android.com/reference/kotlin/java/io/Reader)!`)` Creates a new filtered reader. | | Public methods || |----------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | open[Unit](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-unit/index.html) | [close](https://developer.android.com/reference/kotlin/java/io/FilterReader#close())`()`
| | open[Unit](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-unit/index.html) | [mark](https://developer.android.com/reference/kotlin/java/io/FilterReader#mark(kotlin.Int))`(`readAheadLimit:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`)` Marks the present position in the stream. | | open[Boolean](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-boolean/index.html) | [markSupported](https://developer.android.com/reference/kotlin/java/io/FilterReader#markSupported())`()` Tells whether this stream supports the mark() operation. | | open[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html) | [read](https://developer.android.com/reference/kotlin/java/io/FilterReader#read())`()` Reads a single character. | | open[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html) | [read](https://developer.android.com/reference/kotlin/java/io/FilterReader#read(kotlin.CharArray,%20kotlin.Int,%20kotlin.Int))`(`cbuf:` `[CharArray](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-char-array/index.html)!`, `off:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`, `len:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`)` Reads characters into a portion of an array. | | open[Boolean](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-boolean/index.html) | [ready](https://developer.android.com/reference/kotlin/java/io/FilterReader#ready())`()` Tells whether this stream is ready to be read. | | open[Unit](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-unit/index.html) | [reset](https://developer.android.com/reference/kotlin/java/io/FilterReader#reset())`()` Resets the stream. | | open[Long](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-long/index.html) | [skip](https://developer.android.com/reference/kotlin/java/io/FilterReader#skip(kotlin.Long))`(`n:` `[Long](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-long/index.html)`)` Skips characters. | | Inherited functions || |---|---| | From class[Reader](https://developer.android.com/reference/kotlin/java/io/Reader) |------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | [Reader](https://developer.android.com/reference/kotlin/java/io/Reader)! | [nullReader](https://developer.android.com/reference/kotlin/java/io/Reader#nullReader())`()`
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](https://developer.android.com/reference/kotlin/java/io/Reader#lock:kotlin.Any)used to synchronize operations on the returned`Reader`is not specified.
| | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html) | [read](https://developer.android.com/reference/kotlin/java/io/Reader#read(kotlin.CharArray))`(`cbuf:` `[CharArray](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-char-array/index.html)!`)`
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.
| | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html) | [read](https://developer.android.com/reference/kotlin/java/io/Reader#read(java.nio.CharBuffer))`(`target:` `[CharBuffer](https://developer.android.com/reference/kotlin/java/nio/CharBuffer.html#)!`)`
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.
| | [Long](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-long/index.html) | [transferTo](https://developer.android.com/reference/kotlin/java/io/Reader#transferTo(java.io.Writer))`(`out:` `[Writer](https://developer.android.com/reference/kotlin/java/io/Writer)!`)`
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.
| || | Properties || |--------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------| | [Reader](https://developer.android.com/reference/kotlin/java/io/Reader)! | [in](https://developer.android.com/reference/kotlin/java/io/FilterReader#in:java.io.Reader) The underlying character-input stream. | | Inherited properties || |---|---| | From class[Reader](https://developer.android.com/reference/kotlin/java/io/Reader) |-----------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | [Any](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-any/index.html)! | [lock](https://developer.android.com/reference/kotlin/java/io/Reader#lock:kotlin.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.
| || ## Protected constructors ### FilterReader Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels) ``` protected FilterReader(in: Reader!) ``` Creates a new filtered reader. | Parameters || |------|---------------------------------------------------------------------------------------------------------------------------| | `in` | [Reader](https://developer.android.com/reference/kotlin/java/io/Reader)!:a Reader object providing the underlying stream. | | Exceptions || |----------------------------------|----------------| | `java.lang.NullPointerException` | if`in`is`null` | ## Public methods ### close Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels) ``` open fun close(): Unit ``` | Exceptions || |-----------------------|-----------------------------------| | `java.lang.Exception` | if this resource cannot be closed | | `java.io.IOException` | if an I/O error occurs | ### mark Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels) ``` open fun mark(readAheadLimit: Int): Unit ``` Marks the present position in the stream. | Parameters || |------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | `readAheadLimit` | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html):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 an I/O error occurs | ### markSupported Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels) ``` open fun markSupported(): Boolean ``` Tells whether this stream supports the mark() operation. | Return || |------------------------------------------------------------------------------------|--------------------------------------------------------------| | [Boolean](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-boolean/index.html) | true if and only if this stream supports the mark operation. | ### read Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels) ``` open fun read(): Int ``` Reads a single character. | Return || |----------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------| | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html) | 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](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels) ``` open fun read(     cbuf: CharArray!,     off: Int,     len: Int ): Int ``` Reads characters into a portion of an array. | Parameters || |--------|------------------------------------------------------------------------------------------------------------------------| | `cbuf` | [CharArray](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-char-array/index.html)!:Destination buffer | | `off` | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html):Offset at which to start storing characters | | `len` | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html):Maximum number of characters to read | | Return || |----------------------------------------------------------------------------|--------------------------------------------------------------------------------| | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html) | 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](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels) ``` open fun ready(): Boolean ``` Tells whether this stream is ready to be read. | Return || |------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------| | [Boolean](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-boolean/index.html) | 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](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels) ``` open fun reset(): Unit ``` Resets the stream. | Exceptions || |-----------------------|------------------------| | `java.io.IOException` | If an I/O error occurs | ### skip Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels) ``` open fun skip(n: Long): Long ``` Skips characters. | Parameters || |-----|---------------------------------------------------------------------------------------------------------------| | `n` | [Long](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-long/index.html):The number of characters to skip | | Return || |------------------------------------------------------------------------------|-------------------------------------------| | [Long](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-long/index.html) | The number of characters actually skipped | | Exceptions || |-----------------------|------------------------| | `java.io.IOException` | If an I/O error occurs | ## Properties ### in Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels) ``` protected var in: Reader! ``` The underlying character-input stream.