java.io.DataOutput |
![]() |
The DataOutput
interface provides for converting data from any
of the Java primitive types to a series of bytes and writing these bytes to a
binary stream. There is also a facility for converting a String
into Java modified UTF-8 format and writing the resulting series of bytes.
For all the methods in this interface that write bytes, it is generally true
that if a byte cannot be written for any reason, an IOException
is thrown.
Public Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
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 |
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 |
writeInt(int v)
Writes an
int value, which is comprised of four bytes, to the
output stream. | ||||||||||
abstract void |
writeLong(long v)
Writes an
long value, which is comprised of four 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 str)
Writes two bytes of length information to the output stream, followed by the
Java modified UTF representation of every character in the string
s . |
Writes to the output stream all the bytes in array b
. If
b
is null
, a NullPointerException
is
thrown. If b.length
is zero, then no bytes are written.
Otherwise, the byte b[0]
is written first, then
b[1]
, and so on; the last byte written is
b[b.length-1]
.
b | the data. |
---|
IOException | if an I/O error occurs. |
---|
Writes len
bytes from array b
, in order, to the
output stream. If b
is null
, a
NullPointerException
is thrown. If off
is negative,
or len
is negative, or off+len
is greater than the
length of the array b
, then an
IndexOutOfBoundsException
is thrown. If len
is
zero, then no bytes are written. Otherwise, the byte b[off]
is
written first, then b[off+1]
, and so on; the last byte written
is b[off+len-1]
.
b | the data. |
---|---|
off | the start offset in the data. |
len | the number of bytes to write. |
IOException | if an I/O error occurs. |
---|
Writes to the output stream the eight low-order bits of the argument
b
. The 24 high-order bits of b
are ignored.
b | the byte to be written. |
---|
IOException | if an I/O error occurs. |
---|
Writes a boolean
value to this output stream. If the argument
v
is true
, the value (byte)1
is
written; if v
is false
, the value
(byte)0
is written. The byte written by this method may be read
by the readBoolean
method of interface DataInput
,
which will then return a boolean
equal to v
.
v | the boolean to be written. |
---|
IOException | if an I/O error occurs. |
---|
Writes to the output stream the eight low- order bits of the argument
v
. The 24 high-order bits of v
are ignored. (This
means that writeByte
does exactly the same thing as
write
for an integer argument.) The byte written by this method
may be read by the readByte
method of interface
DataInput
, which will then return a byte
equal to
(byte)v
.
v | the byte value to be written. |
---|
IOException | if an I/O error occurs. |
---|
Writes a char
value, which is comprised of two bytes, to the
output stream. The byte values to be written, in the order shown, are:
(byte)(0xff & (v >> 8))
(byte)(0xff & v)
The bytes written by this method may be read by the readChar
method of interface DataInput
, which will then return a
char
equal to (char)v
.
v | the char value to be written. |
---|
IOException | if an I/O error occurs. |
---|
Writes every character in the string s
, to the output stream, in
order, two bytes per character. If s
is null
, a
NullPointerException
is thrown. If s.length
is
zero, then no characters are written. Otherwise, the character
s[0]
is written first, then s[1]
, and so on; the
last character written is s[s.length-1]
. For each character, two
bytes are actually written, high-order byte first, in exactly the manner of
the writeChar
method.
s | the string value to be written. |
---|
IOException | if an I/O error occurs. |
---|
Writes an int
value, which is comprised of four bytes, to the
output stream. The byte values to be written, in the order shown, are:
(byte)(0xff & (v >> 24))
(byte)(0xff & (v >> 16))
(byte)(0xff & (v >> 8))
(byte)(0xff & v)
The bytes written by this method may be read by the readInt
method of interface DataInput
, which will then return an
int
equal to v
.
v | the int value to be written. |
---|
IOException | if an I/O error occurs. |
---|
Writes an long
value, which is comprised of four bytes, to the
output stream. The byte values to be written, in the order shown, are:
(byte)(0xff & (v >> 48))
(byte)(0xff & (v >> 40))
(byte)(0xff & (v >> 32))
(byte)(0xff & (v >> 24))
(byte)(0xff & (v >> 16))
(byte)(0xff & (v >> 8))
(byte)(0xff & v)
The bytes written by this method may be read by the readLong
method of interface DataInput
, which will then return a
long
equal to v
.
v | the long value to be written. |
---|
IOException | if an I/O error occurs. |
---|
Writes two bytes to the output stream to represent the value of the argument. The byte values to be written, in the order shown, are:
(byte)(0xff & (v >> 8))
(byte)(0xff & v)
The bytes written by this method may be read by the readShort
method of interface DataInput
, which will then return a
short
equal to (short)v
.
v | the short value to be written. |
---|
IOException | if an I/O error occurs. |
---|
Writes two bytes of length information to the output stream, followed by the
Java modified UTF representation of every character in the string
s
. If s
is null
, a
NullPointerException
is thrown. Each character in the string
s
is converted to a group of one, two, or three bytes, depending
on the value of the character.
If a character c
is in the range \u0001
through
\u007f
, it is represented by one byte:
(byte) c
If a character c
is \u0000
or is in the range
\u0080
through \u07ff
, then it is
represented by two bytes, to be written in the order shown:
(byte)(0xc0 | (0x1f & (c >> 6)))
(byte)(0x80 | (0x3f & c))
If a character c
is in the range \u0800
through
uffff
, then it is represented by three bytes, to be written in
the order shown:
(byte)(0xe0 | (0x0f & (c >> 12)))
(byte)(0x80 | (0x3f & (c >> 6)))
(byte)(0x80 | (0x3f & c))
First, the total number of bytes needed to represent all the characters of
s
is calculated. If this number is larger than
65535
, then a UTFDataFormatError
is thrown.
Otherwise, this length is written to the output stream in exactly the manner
of the writeShort
method; after this, the one-, two-, or
three-byte representation of each character in the string s
is
written.
The bytes written by this method may be read by the readUTF
method of interface DataInput
, which will then return a
String
equal to s
.
str | the string value to be written. |
---|
IOException | if an I/O error occurs. |
---|