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Java Fundamental Classes Reference

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The java.io Package
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DataOutputStream

Name

DataOutputStream

Synopsis

Class Name:

java.io.DataOutputStream

Superclass:

java.io.FilterOutputStream

Immediate Subclasses:

None

Interfaces Implemented:

java.io.DataOutput

Availability:

JDK 1.0 or later

Description

The DataOutputStream class defines methods for writing primitive data types to an output stream in a machine-independent manner. Many of the methods of DataOutputStream write a single primitive data type, in binary format, to an underlying output stream. All multibyte quantities are written in a format that stores the most significant byte as the first byte and the least significant byte as the last byte.

Class Summary

public class java.io.DataOutputStream extends java.io.FilterOutputStream
                                      implements java.io.DataOutput {
  // Variables
  protected int written;
  // Constructors
  public DataOutputStream(OutputStream out);
  // Instance Methods
  public void flush();
  public final int size();
  public synchronized void write(int b);
  public synchronized void write(byte[] b, int off, int len);
  public final void writeBoolean(boolean v);
  public final void writeByte(int v);
  public final void writeBytes(String s);
  public final void writeChar(int v);
  public final void writeChars(String s);
  public final void writeDouble(double v);
  public final void writeFloat(float v);
  public final void writeInt(int v);
  public final void writeLong(long v);
  public final void writeShort(int v);
  public final void writeUTF(String str);
}

Variables

written

protected int written

Description

The number of bytes that have been written to this output stream.

Constructors

DataOutputStream

public DataOutputStream(OutputStream out)

Parameters

out

The output stream to use.

Description

This constructor creates a DataOutputStream that uses out as its underlying stream.

Instance Methods

flush

public void flush() throws IOException

Throws

IOException

If any kind of I/O error occurs.

Overrides

FilterOutputStream.flush()

Description

This method flushes the stream, forcing any buffered output to be written. The method calls the flush() method of the underlying output stream.

size

public final int size()

Returns

The number of bytes written.

Description

This method returns the number of bytes that have been written to the stream (i.e., it returns the value of the variable written).

write

public synchronized void write(int b) throws IOException

Parameters

b

The value to write.

Throws

IOException

If any kind of I/O error occurs.

Overrides

FilterOutputStream.write(int)

Implements

DataOutput.write(int)

Description

This method writes the low-order eight bits of b to the underlying stream as a byte.

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

Parameters

b

An array of bytes to write.

off

An offset into the byte array.

len

The number of bytes to write.

Throws

IOException

If any kind of I/O error occurs.

Overrides

FilterOutputStream.write(byte[], int, int)

Implements

DataOutput.write(byte[], int, int)

Description

This method writes len bytes from the given array, starting off elements from the beginning of the array, to the underlying stream.

writeBoolean

public final void writeBoolean(boolean v) throws IOException

Parameters

v

The boolean value to write.

Throws

IOException

If any kind of I/O error occurs.

Implements

DataOutput.writeBoolean()

Description

If v is true, this method writes a byte that contains the value 1 to the underlying stream. If v is false, the method writes a byte that contains the value 0.

writeByte

public final void writeByte(int v) throws IOException

Parameters

v

The value to write.

Throws

IOException

If any kind of I/O error occurs.

Implements

DataOutput.writeByte()

Description

This method writes an 8-bit byte to the underlying stream, using the low-order eight bits of the given integer v.

writeBytes

public final void writeBytes(String s) throws IOException

Parameters

s

The String to write.

Throws

IOException

If any kind of I/O error occurs.

Implements

DataOutput.writeBytes()

Description

This method writes the characters in the given String to the underlying stream as a sequence of 8-bit bytes. The high-order bytes of the characters in the string are ignored.

writeChar

public final void writeChar(int v) throws IOException

Parameters

v

The value to write.

Throws

IOException

If any kind of I/O error occurs.

Implements

DataOutput.writeChar()

Description

This method writes a 16-bit char to the underlying stream, using the low-order 16 bits of the given integer v.

writeChars

public final void writeChars(String s) throws IOException

Parameters

s

The String to write.

Throws

IOException

If any kind of I/O error occurs.

Implements

DataOutput.writeChars()

Description

This method writes the characters in the given String object to the underlying stream as a sequence of 16-bit characters.

writeDouble

public final void writeDouble(double v) throws IOException

Parameters

v

The double value to write.

Throws

IOException

If any kind of I/O error occurs.

Implements

DataOutput.writeDouble()

Description

This method writes a 64-bit double to the underlying stream. The double value is converted to a long using doubleToLongBits() of Double; the long value is then written to the underlying stream as eight bytes with the high-order byte first.

writeFloat

public final void writeFloat(float v) throws IOException

Parameters

v

The float value to write.

Throws

IOException

If any kind of I/O error occurs.

Implements

DataOutput.writeFloat()

Description

This method writes a 32-bit float to the underlying stream. The float value is converted to a int using floatToIntBits() of Float; the int value is then written to the underlying stream as four bytes with the high-order byte first.

writeInt

public final void writeInt(int v) throws IOException

Parameters

v

The int value to write.

Throws

IOException

If any kind of I/O error occurs.

Implements

DataOutput.writeInt()

Description

This method writes a 32-bit int to the underlying stream. The value is written as four bytes with the high-order byte first.

writeLong

public final void writeLong(long v) throws IOException

Parameters

v

The long value to write.

Throws

IOException

If any kind of I/O error occurs.

Implements

DataOutput.writeLong()

Description

This method writes a 64-bit long to the underlying stream. The value is written as eight bytes with the high-order byte first.

writeShort

public final void writeShort(int v) throws IOException

Parameters

v

The value to write.

Throws

IOException

If any kind of I/O error occurs.

Implements

DataOutput.writeShort()

Description

This method writes a 16-bit short to the underlying stream, using the low-order two bytes of the given integer v.

writeUTF

public final void writeUTF(String str) throws IOException

Parameters

str

The String to write.

Throws

IOException

If any kind of I/O error occurs.

Implements

DataOutput.writeUTF()

Description

This method writes the given String to the underlying stream using the UTF-8 encoding. First, two bytes are written as an unsigned short value; this value specifies the number of bytes to follow. The value is the actual number of bytes in the UTF-8 encoding, not the length of the string. Then each character of the string is written as UTF-8 encoded bytes.

See Appendix B, The UTF-8 Encoding for more information on the UTF-8 encoding.

Inherited Methods

Method

Inherited From

Method

Inherited From

clone()

Object

close()

FilterOutputStream

equals(Object)

Object

finalize()

Object

getClass()

Object

hashCode()

Object

notify()

Object

notifyAll()

Object

toString()

Object

wait()

Object

wait(long)

Object

wait(long, int)

Object

write(byte[])

FilterOutputStream

   

See Also

DataInputStream, DataOutput, Double, FilterOutputStream, Float, IOException, OutputStream


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