DataOutputStream

public class DataOutputStream extends FilterOutputStream
implements DataOutput

A data output stream lets an application write primitive Java data types to an output stream in a portable way. An application can then use a data input stream to read the data back in.

See Also

• DataInputStream

Field Summary

protected int

written

The number of bytes written to the data output stream so far.

Inherited Field Summary

From class java.io.FilterOutputStream

protected OutputStream

out

The underlying output stream to be filtered.

Public Constructor Summary

DataOutputStream(OutputStream out) Creates a new data output stream to write data to the specified underlying output stream.

Public Method Summary

void	flush() Flushes this data output stream.
final int	size() Returns the current value of the counter written, the number of bytes written to this data output stream so far.
synchronized void	write(byte[] b, int off, int len) Writes len bytes from the specified byte array starting at offset off to the underlying output stream.
synchronized void	write(int b) Writes the specified byte (the low eight bits of the argument b) to the underlying output stream.
final void	writeBoolean(boolean v) Writes a boolean to the underlying output stream as a 1-byte value.
final void	writeByte(int v) Writes out a byte to the underlying output stream as a 1-byte value.
final void	writeBytes(String s) Writes out the string to the underlying output stream as a sequence of bytes.
final void	writeChar(int v) Writes a char to the underlying output stream as a 2-byte value, high byte first.
final void	writeChars(String s) Writes a string to the underlying output stream as a sequence of characters.
final void	writeDouble(double v) Converts the double argument to a long using the doubleToLongBits method in class Double, and then writes that long value to the underlying output stream as an 8-byte quantity, high byte first.
final void	writeFloat(float v) Converts the float argument to an int using the floatToIntBits method in class Float, and then writes that int value to the underlying output stream as a 4-byte quantity, high byte first.
final void	writeInt(int v) Writes an int to the underlying output stream as four bytes, high byte first.
final void	writeLong(long v) Writes a long to the underlying output stream as eight bytes, high byte first.
final void	writeShort(int v) Writes a short to the underlying output stream as two bytes, high byte first.
final void	writeUTF(String str) Writes a string to the underlying output stream using modified UTF-8 encoding in a machine-independent manner.

Inherited Method Summary

From class java.io.FilterOutputStream

void	close() Closes this output stream and releases any system resources associated with the stream.
void	flush() Flushes this output stream and forces any buffered output bytes to be written out to the stream.
void	write(byte[] b) Writes b.length bytes to this output stream.
void	write(byte[] b, int off, int len) Writes len bytes from the specified byte array starting at offset off to this output stream.
void	write(int b) Writes the specified byte to this output stream.

From class java.io.OutputStream

void	close() Closes this output stream and releases any system resources associated with this stream.
void	flush() Flushes this output stream and forces any buffered output bytes to be written out.
void	write(byte[] b) Writes b.length bytes from the specified byte array to this output stream.
void	write(byte[] b, int off, int len) Writes len bytes from the specified byte array starting at offset off to this output stream.
abstract void	write(int b) Writes the specified byte to this output stream.

From class java.lang.Object

Object	clone() Creates and returns a copy of this Object.
boolean	equals(Object obj) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of Class that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long timeout, int nanos) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait(long timeout) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object.

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.io.DataOutput

abstract void	write(byte[] b) Writes to the output stream all the bytes in array b.
abstract void	write(byte[] b, int off, int len) Writes len bytes from array b, in order, to the output stream.
abstract void	write(int b) Writes to the output stream the eight low-order bits of the argument b.
abstract void	writeBoolean(boolean v) Writes a boolean value to this output stream.
abstract void	writeByte(int v) Writes to the output stream the eight low- order bits of the argument v.
abstract void	writeBytes(String s) Writes a string to the output stream.
abstract void	writeChar(int v) Writes a char value, which is comprised of two bytes, to the output stream.
abstract void	writeChars(String s) Writes every character in the string s, to the output stream, in order, two bytes per character.
abstract void	writeDouble(double v) Writes a double value, which is comprised of eight bytes, to the output stream.
abstract void	writeFloat(float v) Writes a float value, which is comprised of four bytes, to the output stream.
abstract void	writeInt(int v) Writes an int value, which is comprised of four bytes, to the output stream.
abstract void	writeLong(long v) Writes a long value, which is comprised of eight bytes, to the output stream.
abstract void	writeShort(int v) Writes two bytes to the output stream to represent the value of the argument.
abstract void	writeUTF(String s) Writes two bytes of length information to the output stream, followed by the modified UTF-8 representation of every character in the string s.

From interface java.lang.AutoCloseable

abstract void

close() Closes this resource, relinquishing any underlying resources.

Fields

protected int written

The number of bytes written to the data output stream so far. If this counter overflows, it will be wrapped to Integer.MAX_VALUE.

Public Constructors

public DataOutputStream (OutputStream out)

Creates a new data output stream to write data to the specified underlying output stream. The counter written is set to zero.

Parameters

out	the underlying output stream, to be saved for later use.

See Also

• FilterOutputStream.out

Public Methods

public void flush ()

Flushes this data output stream. This forces any buffered output bytes to be written out to the stream.

The flush method of DataOutputStream calls the flush method of its underlying output stream.

Throws

IOException	if an I/O error occurs.

See Also

• FilterOutputStream.out
• OutputStream.flush()

public final int size ()

Returns the current value of the counter written, the number of bytes written to this data output stream so far. If the counter overflows, it will be wrapped to Integer.MAX_VALUE.

Returns

• the value of the written field.

See Also

• written

public synchronized void write (byte[] b, int off, int len)

Writes len bytes from the specified byte array starting at offset off to the underlying output stream. If no exception is thrown, the counter written is incremented by len.

Parameters

b	the data.
off	the start offset in the data.
len	the number of bytes to write.

Throws

IOException	if an I/O error occurs.

See Also

• FilterOutputStream.out

public synchronized void write (int b)

Writes the specified byte (the low eight bits of the argument b) to the underlying output stream. If no exception is thrown, the counter written is incremented by 1.

Implements the write method of OutputStream.

Parameters

b	the byte to be written.

Throws

IOException	if an I/O error occurs.

See Also

• FilterOutputStream.out

public final void writeBoolean (boolean v)

Writes a boolean to the underlying output stream as a 1-byte value. The value true is written out as the value (byte)1; the value false is written out as the value (byte)0. If no exception is thrown, the counter written is incremented by 1.

Parameters

v	a boolean value to be written.

Throws

IOException	if an I/O error occurs.

See Also

• FilterOutputStream.out

public final void writeByte (int v)

Writes out a byte to the underlying output stream as a 1-byte value. If no exception is thrown, the counter written is incremented by 1.

Parameters

v	a byte value to be written.

Throws

IOException	if an I/O error occurs.

See Also

• FilterOutputStream.out

public final void writeBytes (String s)

Writes out the string to the underlying output stream as a sequence of bytes. Each character in the string is written out, in sequence, by discarding its high eight bits. If no exception is thrown, the counter written is incremented by the length of s.

Parameters

s	a string of bytes to be written.

Throws

IOException	if an I/O error occurs.

See Also

• FilterOutputStream.out

public final void writeChar (int v)

Writes a char to the underlying output stream as a 2-byte value, high byte first. If no exception is thrown, the counter written is incremented by 2.

Parameters

v	a char value to be written.

Throws

IOException	if an I/O error occurs.

See Also

• FilterOutputStream.out

public final void writeChars (String s)

Writes a string to the underlying output stream as a sequence of characters. Each character is written to the data output stream as if by the writeChar method. If no exception is thrown, the counter written is incremented by twice the length of s.

Parameters

s	a String value to be written.

Throws

IOException	if an I/O error occurs.

See Also

• writeChar(int)
• FilterOutputStream.out

public final void writeDouble (double v)

Converts the double argument to a long using the doubleToLongBits method in class Double, and then writes that long value to the underlying output stream as an 8-byte quantity, high byte first. If no exception is thrown, the counter written is incremented by 8.

Parameters

v	a double value to be written.

Throws

IOException	if an I/O error occurs.

See Also

• FilterOutputStream.out
• Double.doubleToLongBits(double)

public final void writeFloat (float v)

Converts the float argument to an int using the floatToIntBits method in class Float, and then writes that int value to the underlying output stream as a 4-byte quantity, high byte first. If no exception is thrown, the counter written is incremented by 4.

Parameters

v	a float value to be written.

Throws

IOException	if an I/O error occurs.

See Also

• FilterOutputStream.out
• Float.floatToIntBits(float)

public final void writeInt (int v)

Writes an int to the underlying output stream as four bytes, high byte first. If no exception is thrown, the counter written is incremented by 4.

Parameters

v	an int to be written.

Throws

IOException	if an I/O error occurs.

See Also

• FilterOutputStream.out

public final void writeLong (long v)

Writes a long to the underlying output stream as eight bytes, high byte first. In no exception is thrown, the counter written is incremented by 8.

Parameters

v	a long to be written.

Throws

IOException	if an I/O error occurs.

See Also

• FilterOutputStream.out

public final void writeShort (int v)

Writes a short to the underlying output stream as two bytes, high byte first. If no exception is thrown, the counter written is incremented by 2.

Parameters

v	a short to be written.

Throws

IOException	if an I/O error occurs.

See Also

• FilterOutputStream.out

public final void writeUTF (String str)

Writes a string to the underlying output stream using modified UTF-8 encoding in a machine-independent manner.

First, two bytes are written to the output stream as if by the writeShort method giving the number of bytes to follow. This value is the number of bytes actually written out, not the length of the string. Following the length, each character of the string is output, in sequence, using the modified UTF-8 encoding for the character. If no exception is thrown, the counter written is incremented by the total number of bytes written to the output stream. This will be at least two plus the length of str, and at most two plus thrice the length of str.

Parameters

str	a string to be written.

Throws

IOException	if an I/O error occurs.