java.io
Class DataOutputStream
- AutoCloseable, Closeable, DataOutput, Flushable
This class provides a mechanism for writing primitive Java datatypes
to an OutputStream in a portable way. Data written to
a stream using this class can be read back in using the
DataInputStream class on any platform.
protected int | written- This is the total number of bytes that have been written to the
stream by this object instance.
|
DataOutputStream(OutputStream out)- This method initializes an instance of
DataOutputStream to
write its data to the specified underlying OutputStream
|
void | flush()- This method flushes any unwritten bytes to the underlying stream.
|
int | size()- This method returns the total number of bytes that have been written to
the underlying output stream so far.
|
void | write(byte[] buf, int offset, int len)- This method writes
len bytes from the specified byte array
buf starting at position offset into the
buffer to the underlying output stream.
|
void | write(int value)- This method writes the specified byte (passed as an
int)
to the underlying output stream.
|
void | writeBoolean(boolean value)- This method writes a Java boolean value to an output stream.
|
void | writeByte(int value)- This method writes a Java byte value to an output stream.
|
void | writeBytes(String value)- This method writes all the bytes in a
String out to the
stream.
|
void | writeChar(int value)- This method writes a Java char value to an output stream.
|
void | writeChars(String value)- This method writes all the characters of a
String to an
output stream as an array of char's.
|
void | writeDouble(double value)- This method writes a Java
double value to the stream.
|
void | writeFloat(float value)- This method writes a Java
float value to the stream.
|
void | writeInt(int value)- This method writes a Java int value to an output stream.
|
void | writeLong(long value)- This method writes a Java long value to an output stream.
|
void | writeShort(int value)- This method writes a Java short value to an output stream.
|
void | writeUTF(String value)- This method writes a Java
String to the stream in a modified
UTF-8 format.
|
clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait |
written
protected int written
This is the total number of bytes that have been written to the
stream by this object instance.
DataOutputStream
public DataOutputStream(OutputStream out)
This method initializes an instance of DataOutputStream to
write its data to the specified underlying OutputStream
out - The subordinate OutputStream to which this
object will write
size
public final int size()
This method returns the total number of bytes that have been written to
the underlying output stream so far. This is the value of the
written instance variable
- The number of bytes written to the stream.
write
public void write(byte[] buf,
int offset,
int len)
throws IOException This method writes len bytes from the specified byte array
buf starting at position offset into the
buffer to the underlying output stream.
- write in interface DataOutput
- write in interface FilterOutputStream
buf - The byte array to write from.offset - The index into the byte array to start writing from.len - The number of bytes to write.
writeBoolean
public final void writeBoolean(boolean value)
throws IOException This method writes a Java boolean value to an output stream. If
value is true, a byte with the value of
1 will be written, otherwise a byte with the value of 0 will be
written.
The value written can be read using the readBoolean
method in DataInput.
- writeBoolean in interface DataOutput
value - The boolean value to write to the stream
writeByte
public final void writeByte(int value)
throws IOException This method writes a Java byte value to an output stream. The
byte to be written will be in the lowest 8 bits of the
int value passed.
The value written can be read using the readByte or
readUnsignedByte methods in DataInput.
- writeByte in interface DataOutput
value - The byte to write to the stream, passed as
the low eight bits of an int.
writeBytes
public final void writeBytes(String value)
throws IOException This method writes all the bytes in a String out to the
stream. One byte is written for each character in the
String.
The high eight bits of each character are discarded, thus this
method is inappropriate for completely representing Unicode characters.
- writeBytes in interface DataOutput
value - The String to write to the stream
writeChar
public final void writeChar(int value)
throws IOException This method writes a Java char value to an output stream. The
char to be written will be in the lowest 16 bits of the
int
value passed. These bytes will be written "big endian". That is,
with the high byte written first in the following manner:
byte0 = (byte)((value & 0xFF00) >> 8);
byte1 = (byte)(value & 0x00FF);
The value written can be read using the
readChar
method in
DataInput.
- writeChar in interface DataOutput
value - The char value to write,
passed as an int.
writeChars
public final void writeChars(String value)
throws IOException This method writes all the characters of a String to an
output stream as an array of char's. Each character
is written using the method specified in the writeChar
method.
- writeChars in interface DataOutput
value - The String to write to the stream
writeDouble
public final void writeDouble(double value)
throws IOException This method writes a Java double value to the stream. This
value is written by first calling the method
Double.doubleToLongBits
to retrieve an long representing the floating point number,
then writing this long value to the stream exactly the same
as the writeLong() method does.
The value written can be read using the readDouble
method in DataInput.
- writeDouble in interface DataOutput
value - The double value to write to the stream
writeFloat
public final void writeFloat(float value)
throws IOException This method writes a Java float value to the stream. This
value is written by first calling the method
Float.floatToIntBits
to retrieve an int representing the floating point number,
then writing this int value to the stream exactly the same
as the writeInt() method does.
The value written can be read using the readFloat
method in DataInput.
- writeFloat in interface DataOutput
value - The float value to write to the stream
writeInt
public final void writeInt(int value)
throws IOException This method writes a Java int value to an output stream. The 4 bytes
of the passed value will be written "big endian". That is, with
the high byte written first in the following manner:
byte0 = (byte)((value & 0xFF000000) >> 24);
byte1 = (byte)((value & 0x00FF0000) >> 16);
byte2 = (byte)((value & 0x0000FF00) >> 8);
byte3 = (byte)(value & 0x000000FF);
The value written can be read using the
readInt
method in
DataInput.
- writeInt in interface DataOutput
value - The int value to write to the stream
writeLong
public final void writeLong(long value)
throws IOException This method writes a Java long value to an output stream. The 8 bytes
of the passed value will be written "big endian". That is, with
the high byte written first in the following manner:
byte0 = (byte)((value & 0xFF00000000000000L) >> 56);
byte1 = (byte)((value & 0x00FF000000000000L) >> 48);
byte2 = (byte)((value & 0x0000FF0000000000L) >> 40);
byte3 = (byte)((value & 0x000000FF00000000L) >> 32);
byte4 = (byte)((value & 0x00000000FF000000L) >> 24);
byte5 = (byte)((value & 0x0000000000FF0000L) >> 16);
byte6 = (byte)((value & 0x000000000000FF00L) >> 8);
byte7 = (byte)(value & 0x00000000000000FFL);
The value written can be read using the
readLong
method in
DataInput.
- writeLong in interface DataOutput
value - The long value to write to the stream
writeShort
public final void writeShort(int value)
throws IOException This method writes a Java short value to an output stream. The
char to be written will be in the lowest 16 bits of the
int
value passed. These bytes will be written "big endian". That is,
with the high byte written first in the following manner:
byte0 = (byte)((value & 0xFF00) >> 8);
byte1 = (byte)(value & 0x00FF);
The value written can be read using the
readShort and
readUnsignedShort methods in
DataInput.
- writeShort in interface DataOutput
value - The short value to write to the stream,
passed as an int.
writeUTF
public final void writeUTF(String value)
throws IOException This method writes a Java String to the stream in a modified
UTF-8 format. First, two bytes are written to the stream indicating the
number of bytes to follow. Note that this is the number of bytes in the
encoded String not the String length. Next
come the encoded characters. Each character in the String
is encoded as either one, two or three bytes. For characters in the
range of \u0001 to <\u007F>, one byte is used. The character
value goes into bits 0-7 and bit eight is 0. For characters in the range
of \u0080 to \u007FF, two bytes are used. Bits
6-10 of the character value are encoded bits 0-4 of the first byte, with
the high bytes having a value of "110". Bits 0-5 of the character value
are stored in bits 0-5 of the second byte, with the high bits set to
"10". This type of encoding is also done for the null character
\u0000. This eliminates any C style NUL character values
in the output. All remaining characters are stored as three bytes.
Bits 12-15 of the character value are stored in bits 0-3 of the first
byte. The high bits of the first bytes are set to "1110". Bits 6-11
of the character value are stored in bits 0-5 of the second byte. The
high bits of the second byte are set to "10". And bits 0-5 of the
character value are stored in bits 0-5 of byte three, with the high bits
of that byte set to "10".
The value written can be read using the readUTF
method in DataInput.
- writeUTF in interface DataOutput
value - The String to write to the output in UTF format
DataOutputStream.java -- Writes primitive Java datatypes to streams
Copyright (C) 1998, 2001, 2003, 2005, 2008 Free Software Foundation, Inc.
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