FilterReader | API reference | Android Developers

Added in API level 1

Summary: Fields | Inherited Fields | Protected Ctors | Methods | Inherited Methods

FilterReader

public abstract class FilterReader
extends Reader

Known direct subclasses

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

Fields
`protected Reader`	`in` The underlying character-input stream.

Inherited fields

From class java.io.Reader


    protected
    
    
    Object

lock

The object used to synchronize operations on this stream.

Protected constructors
`FilterReader(Reader in)` Creates a new filtered reader.

Public methods
`void`	`close()` Closes the stream and releases any system resources associated with it.
`void`	`mark(int readAheadLimit)` Marks the present position in the stream.
`boolean`	`markSupported()` Tells whether this stream supports the mark() operation.
`int`	`read()` Reads a single character.
`int`	`read(char[] cbuf, int off, int len)` Reads characters into a portion of an array.
`boolean`	`ready()` Tells whether this stream is ready to be read.
`void`	`reset()` Resets the stream.
`long`	`skip(long n)` Skips characters.

Inherited methods

From class


        
          java.io.Reader

`abstract void`	`close()` Closes the stream and releases any system resources associated with it.
`void`	`mark(int readAheadLimit)` Marks the present position in the stream.
`boolean`	`markSupported()` Tells whether this stream supports the mark() operation.
`static Reader`	`nullReader()` Returns a new `Reader` that reads no characters.
`int`	`read()` Reads a single character.
`abstract int`	`read(char[] cbuf, int off, int len)` Reads characters into a portion of an array.
`int`	`read(char[] cbuf)` Reads characters into an array.
`int`	`read(CharBuffer target)` Attempts to read characters into the specified character buffer.
`boolean`	`ready()` Tells whether this stream is ready to be read.
`void`	`reset()` Resets the stream.
`long`	`skip(long n)` Skips characters.
`long`	`transferTo(Writer out)` Reads all characters from this reader and writes the characters to the given writer in the order that they are read.

From class


        
          java.lang.Object

`Object`	`clone()` Creates and returns a copy of this object.
`boolean`	`equals(Object obj)` Indicates whether some other object is "equal to" this one.
`void`	`finalize()` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
`final Class<?>`	`getClass()` Returns the runtime class of this `Object`.
`int`	`hashCode()` Returns a hash code value for the object.
`final void`	`notify()` Wakes up a single thread that is waiting on this object's monitor.
`final void`	`notifyAll()` Wakes up all threads that are waiting on this object's monitor.
`String`	`toString()` Returns a string representation of the object.
`final void`	`wait(long timeoutMillis, int nanos)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait(long timeoutMillis)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait()` Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

From interface


        
          java.io.Closeable


      close()

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

From interface


        
          java.lang.Readable


      read(CharBuffer cb)

Attempts to read characters into the specified character buffer.

From interface


        
          java.lang.AutoCloseable


      close()

Closes this resource, relinquishing any underlying resources.

Fields

in

Added in API level 1

protected Reader in

The underlying character-input stream.

Protected constructors

FilterReader

Added in API level 1

protected FilterReader (Reader in)

Creates a new filtered reader.

Parameters
`in`	`Reader`: a Reader object providing the underlying stream.

Throws
`NullPointerException`	if `in` is `null`

Public methods

close

Added in API level 1

public 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`

mark

Added in API level 1

public void mark (int readAheadLimit)

Marks the present position in the stream.

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.

Throws
`IOException`	If an I/O error occurs

markSupported

Added in API level 1

public boolean markSupported ()

Tells whether this stream supports the mark() operation.

Returns
`boolean`	true if and only if this stream supports the mark operation.

read

Added in API level 1

public int read ()

Reads a single character.

Returns
`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

Throws
`IOException`	If an I/O error occurs

read

Added in API level 1

public int read (char[] cbuf, 
                int off, 
                int len)

Reads characters into a portion of an array.

Parameters
`cbuf`	`char`: Destination buffer
`off`	`int`: Offset at which to start storing characters
`len`	`int`: Maximum number of characters to read

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

Throws
`IOException`	If an I/O error occurs
`IndexOutOfBoundsException`

ready

Added in API level 1

public boolean ready ()

Tells whether this stream is ready to be read.

Returns
`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.

Throws
`IOException`	If an I/O error occurs

reset

Added in API level 1

public void reset ()

Resets the stream.

Throws
`IOException`	If an I/O error occurs

skip

Added in API level 1

public long skip (long n)

Skips characters.

Parameters
`n`	`long`: The number of characters to skip

Returns
`long`	The number of characters actually skipped

Throws
`IOException`	If an I/O error occurs

Content and code samples on this page are subject to the licenses described in the Content License. Java and OpenJDK are trademarks or registered trademarks of Oracle and/or its affiliates.

Last updated 2026-08-03 UTC.

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java.lang.Object
↳	java.io.Reader
	↳	java.io.FilterReader

Sunbelt Computer Software

PL/B Language Development and Support

FilterReader

Summary

Fields

Inherited fields

Protected constructors

Public methods

Inherited methods

Fields

in

Protected constructors

FilterReader

Public methods

close

mark

markSupported

read

read

ready

reset

skip