Summary: Fields | Protected Ctors | Methods | Inherited Methods

Writer

public abstract class Writer
extends Object implements Appendable, Closeable, Flushable

java.lang.Object
↳	java.io.Writer

Known direct subclasses

BufferedWriter, CharArrayWriter, FilterWriter, OutputStreamWriter, PipedWriter, PrintWriter, StringWriter

BufferedWriter	Writes text to a character-output stream, buffering characters so as to provide for the efficient writing of single characters, arrays, and strings.
CharArrayWriter	This class implements a character buffer that can be used as an Writer.
FilterWriter	Abstract class for writing filtered character streams.
OutputStreamWriter	An OutputStreamWriter is a bridge from character streams to byte streams: Characters written to it are encoded into bytes using a specified `charset`.
PipedWriter	Piped character-output streams.
PrintWriter	Prints formatted representations of objects to a text-output stream.
StringWriter	A character stream that collects its output in a string buffer, which can then be used to construct a string.

Known indirect subclasses

FileWriter

FileWriter Writes text to character files using a default buffer size.

Abstract class for writing to character streams. The only methods that a subclass must implement are write(char[], int, int), flush(), 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:

Summary

Fields
`protected Object`	`lock` The object used to synchronize operations on this stream.

Protected constructors
`Writer()` Creates a new character-stream writer whose critical sections will synchronize on the writer itself.
`Writer(Object lock)` Creates a new character-stream writer whose critical sections will synchronize on the given object.

Public methods
`Writer`	`append(char c)` Appends the specified character to this writer.
`Writer`	`append(CharSequence csq, int start, int end)` Appends a subsequence of the specified character sequence to this writer.
`Writer`	`append(CharSequence csq)` Appends the specified character sequence to this writer.
`abstract void`	`close()` Closes the stream, flushing it first.
`abstract void`	`flush()` Flushes the stream.
`static Writer`	`nullWriter()` Returns a new `Writer` which discards all characters.
`void`	`write(String str)` Writes a string.
`void`	`write(int c)` Writes a single character.
`void`	`write(String str, int off, int len)` Writes a portion of a string.
`abstract void`	`write(char[] cbuf, int off, int len)` Writes a portion of an array of characters.
`void`	`write(char[] cbuf)` Writes an array of characters.

Inherited methods

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.lang.Appendable

`abstract Appendable`	`append(char c)` Appends the specified character to this `Appendable`.
`abstract Appendable`	`append(CharSequence csq, int start, int end)` Appends a subsequence of the specified character sequence to this `Appendable`.
`abstract Appendable`	`append(CharSequence csq)` Appends the specified character sequence to this `Appendable`.

From interface java.io.Closeable

abstract void

close()

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

From interface java.io.Flushable

abstract void

flush()

Flushes this stream by writing any buffered output to the underlying stream.

From interface java.lang.AutoCloseable

abstract void

close()

Closes this resource, relinquishing any underlying resources.

Fields

lock

Added in API level 1

 protected Object 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

Writer

Added in API level 1

 protected Writer ()

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

Writer

Added in API level 1

 protected Writer (Object lock)

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

Parameters
`lock`	`Object`: Object to synchronize on

Public methods

append

Added in API level 1

 public Writer append (char c)

Appends the specified character to this writer.

An invocation of this method of the form out.append(c) behaves in exactly the same way as the invocation

 out.write(c)

Parameters
`c`	`char`: The 16-bit character to append

Returns
`Writer`	This writer

Throws
`IOException`	If an I/O error occurs

append

Added in API level 1

 public Writer append (CharSequence csq, int start, int end)

Appends a subsequence of the specified character sequence to this writer. Appendable.

An invocation of this method of the form out.append(csq, start, end) when csq is not null behaves in exactly the same way as the invocation

out.write(csq.subSequence(start, end).toString())

Parameters
`csq`	`CharSequence`: The character sequence from which a subsequence will be appended. If `csq` is `null`, then characters will be appended as if `csq` contained the four characters `"null"`.
`start`	`int`: The index of the first character in the subsequence
`end`	`int`: The index of the character following the last character in the subsequence

Returns
`Writer`	This writer

Throws
`IndexOutOfBoundsException`	If `start` or `end` are negative, `start` is greater than `end`, or `end` is greater than `csq.length()`
`IOException`	If an I/O error occurs

append

Added in API level 1

 public Writer append (CharSequence csq)

Appends the specified character sequence to this writer.

An invocation of this method of the form out.append(csq) behaves in exactly the same way as the invocation

 out.write(csq.toString())

Depending on the specification of toString for the character sequence csq, the entire sequence may not be appended. For instance, invoking the toString method of a character buffer will return a subsequence whose content depends upon the buffer's position and limit.

Parameters
`csq`	`CharSequence`: The character sequence to append. If `csq` is `null`, then the four characters `"null"` are appended to this writer.

Returns
`Writer`	This writer

Throws
`IOException`	If an I/O error occurs

close

Added in API level 1

 public abstract void close ()

Closes the stream, flushing it first. Once the stream has been closed, further write() or flush() invocations will cause an IOException to be thrown. Closing a previously closed stream has no effect.

Throws
`IOException`	If an I/O error occurs

flush

Added in API level 1

 public abstract void flush ()

Flushes the stream. If the stream has saved any characters from the various write() methods in a buffer, write them immediately to their intended destination. Then, if that destination is another character or byte stream, flush it. Thus one flush() invocation will flush all the buffers in a chain of Writers and OutputStreams.

If the intended destination of this stream is an abstraction provided by the underlying operating system, for example a file, then flushing the stream guarantees only that bytes previously written to the stream are passed to the operating system for writing; it does not guarantee that they are actually written to a physical device such as a disk drive.

Throws
`IOException`	If an I/O error occurs

nullWriter

Added in API level 33

 public static Writer nullWriter ()

Returns a new Writer which discards all 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 append(char), append(CharSequence), append(CharSequence, int, int), flush(), write(int), write(char[]), and write(char[], int, int) methods do nothing. After the stream has been closed, these methods all throw IOException.

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

Returns
`Writer`	a `Writer` which discards all characters

write

Added in API level 1

 public void write (String str)

Writes a string.

Parameters
`str`	`String`: String to be written

Throws
`IOException`	If an I/O error occurs

write

Added in API level 1

 public void write (int c)

Writes a single character. The character to be written is contained in the 16 low-order bits of the given integer value; the 16 high-order bits are ignored.

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

Parameters
`c`	`int`: int specifying a character to be written

Throws
`IOException`	If an I/O error occurs

write

Added in API level 1

 public void write (String str, int off, int len)

Writes a portion of a string.

Implementation Requirements:

The implementation in this class throws an IndexOutOfBoundsException for the indicated conditions; overriding methods may choose to do otherwise.

Parameters
`str`	`String`: A String
`off`	`int`: Offset from which to start writing characters
`len`	`int`: Number of characters to write

Throws
`IndexOutOfBoundsException`	Implementations should throw this exception if `off` is negative, or `len` is negative, or `off + len` is negative or greater than the length of the given string
`IOException`	If an I/O error occurs

write

Added in API level 1

 public abstract void write (char[] cbuf, int off, int len)

Writes a portion of an array of characters.

Parameters
`cbuf`	`char`: Array of characters
`off`	`int`: Offset from which to start writing characters
`len`	`int`: Number of characters to write

Throws
`IndexOutOfBoundsException`	Implementations should throw this exception if `off` is negative, or `len` is negative, or `off + len` is negative or greater than the length of the given array
`IOException`	If an I/O error occurs

write

Added in API level 1

 public void write (char[] cbuf)

Writes an array of characters.

Parameters
`cbuf`	`char`: Array of characters to be written

Throws
`IOException`	If an I/O error occurs