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Writer

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

java.lang.Object
   ↳ java.io.Writer
Known Direct Subclasses
Known Indirect Subclasses


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.

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
From interface java.lang.Appendable
From interface java.io.Closeable
From interface java.io.Flushable
From interface java.lang.AutoCloseable

Fields

lock

Added in API level 1
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
Writer ()

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

Writer

Added in API level 1
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
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
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
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
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
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

write

Added in API level 1
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
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
void write (String str, 
                int off, 
                int len)

Writes a portion of a string.

Parameters
str String: A String
off int: Offset from which to start writing characters
len int: Number of characters to write
Throws
IndexOutOfBoundsException 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
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
IOException If an I/O error occurs

write

Added in API level 1
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
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