|
|||||||||
PREV CLASS NEXT CLASS | FRAMES NO FRAMES | ||||||||
SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |
public interface 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.
DataInput
,
DataOutputStream
Method Summary | |
---|---|
void |
write(byte[] b)
Writes to the output stream all the bytes in array b . |
void |
write(byte[] b,
int off,
int len)
Writes len bytes from array b , in order,
to the output stream. |
void |
write(int b)
Writes to the output stream the eight low-order bits of the argument b . |
void |
writeBoolean(boolean v)
Writes a boolean value to this output stream. |
void |
writeByte(int v)
Writes to the output stream the eight low- order bits of the argument v . |
void |
writeChar(int v)
Writes a char value, which is comprised of two bytes, to
the output stream. |
void |
writeChars(String s)
Writes every character in the string s , to the output
stream, in order, two bytes per character. |
void |
writeInt(int v)
Writes an int value, which is comprised of four bytes, to
the output stream. |
void |
writeLong(long v)
Writes an long value, which is comprised of four bytes, to
the output stream. |
void |
writeShort(int v)
Writes two bytes to the output stream to represent the value of the argument. |
void |
writeUTF(String s)
Writes two bytes of length information to the output stream, followed by the Java modified UTF representation of every character in the string s . |
Method Detail |
---|
void write(int b) throws IOException
b
. The 24 high-order bits of b
are
ignored.
b
- the byte to be written.
IOException
- if an I/O error occurs.void write(byte[] b) throws IOException
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.void write(byte[] b, int off, int len) throws IOException
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.void writeBoolean(boolean v) throws IOException
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.void writeByte(int v) throws IOException
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.void writeShort(int v) throws IOException
(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.void writeChar(int v) throws IOException
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.void writeInt(int v) throws IOException
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.void writeLong(long v) throws IOException
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 >> 56))
(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.void writeChars(String s) throws IOException
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.void writeUTF(String s) throws IOException
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
.
s
- the string value to be written.
IOException
- if an I/O error occurs.
|
|||||||||
PREV CLASS NEXT CLASS | FRAMES NO FRAMES | ||||||||
SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |