Interface DataOutput
- All Known Subinterfaces:
-
ImageOutputStream
,ObjectOutput
- All Known Implementing Classes:
-
DataOutputStream
,FileCacheImageOutputStream
,FileImageOutputStream
,ImageOutputStreamImpl
,MemoryCacheImageOutputStream
,ObjectOutputStream
,RandomAccessFile
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 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.
- Since:
- 1.0
- See Also:
-
DataInput
,DataOutputStream
Method Summary
Modifier and Type | Method | Description |
---|---|---|
void | write(byte[] b) | Writes to the output stream all the bytes in array |
void | write(byte[] b,
int off,
int len) | Writes |
void | write(int b) | Writes to the output stream the eight low-order bits of the argument |
void | writeBoolean(boolean v) | Writes a |
void | writeByte(int v) | Writes to the output stream the eight low- order bits of the argument |
void | writeBytes(String s) | Writes a string to the output stream. |
void | writeChar(int v) | Writes a |
void | writeChars(String s) | Writes every character in the string |
void | writeDouble(double v) | Writes a |
void | writeFloat(float v) | Writes a |
void | writeInt(int v) | Writes an |
void | writeLong(long v) | Writes a |
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 modified UTF-8 representation of every character in the string |
Method Detail
write
void write(int b) throws IOException
Writes to the output stream the eight low-order bits of the argument b
. The 24 high-order bits of b
are ignored.
- Parameters:
-
b
- the byte to be written. - Throws:
-
IOException
- if an I/O error occurs.
write
void write(byte[] b) throws IOException
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]
.
- Parameters:
-
b
- the data. - Throws:
-
IOException
- if an I/O error occurs.
write
void write(byte[] b, int off, int len) throws IOException
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]
.
- 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.
writeBoolean
void writeBoolean(boolean v) throws IOException
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
.
- Parameters:
-
v
- the boolean to be written. - Throws:
-
IOException
- if an I/O error occurs.
writeByte
void writeByte(int v) throws IOException
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
.
- Parameters:
-
v
- the byte value to be written. - Throws:
-
IOException
- if an I/O error occurs.
writeShort
void writeShort(int v) throws IOException
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
.
- Parameters:
-
v
- theshort
value to be written. - Throws:
-
IOException
- if an I/O error occurs.
writeChar
void writeChar(int v) throws IOException
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
.
- Parameters:
-
v
- thechar
value to be written. - Throws:
-
IOException
- if an I/O error occurs.
writeInt
void writeInt(int v) throws IOException
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
.
- Parameters:
-
v
- theint
value to be written. - Throws:
-
IOException
- if an I/O error occurs.
writeLong
void writeLong(long v) throws IOException
Writes a long
value, which is comprised of eight 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
.
- Parameters:
-
v
- thelong
value to be written. - Throws:
-
IOException
- if an I/O error occurs.
writeFloat
void writeFloat(float v) throws IOException
Writes a float
value, which is comprised of four bytes, to the output stream. It does this as if it first converts this float
value to an int
in exactly the manner of the Float.floatToIntBits
method and then writes the int
value in exactly the manner of the writeInt
method. The bytes written by this method may be read by the readFloat
method of interface DataInput
, which will then return a float
equal to v
.
- Parameters:
-
v
- thefloat
value to be written. - Throws:
-
IOException
- if an I/O error occurs.
writeDouble
void writeDouble(double v) throws IOException
Writes a double
value, which is comprised of eight bytes, to the output stream. It does this as if it first converts this double
value to a long
in exactly the manner of the Double.doubleToLongBits
method and then writes the long
value in exactly the manner of the writeLong
method. The bytes written by this method may be read by the readDouble
method of interface DataInput
, which will then return a double
equal to v
.
- Parameters:
-
v
- thedouble
value to be written. - Throws:
-
IOException
- if an I/O error occurs.
writeBytes
void writeBytes(String s) throws IOException
Writes a string to the output stream. For every character in the string s
, taken in order, one byte is written to the output stream. If s
is null
, a NullPointerException
is thrown.
If s.length
is zero, then no bytes 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, one byte is written, the low-order byte, in exactly the manner of the writeByte
method . The high-order eight bits of each character in the string are ignored.
- Parameters:
-
s
- the string of bytes to be written. - Throws:
-
IOException
- if an I/O error occurs.
writeChars
void writeChars(String s) throws IOException
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.
- Parameters:
-
s
- the string value to be written. - Throws:
-
IOException
- if an I/O error occurs.
writeUTF
void writeUTF(String s) throws IOException
Writes two bytes of length information to the output stream, followed by the modified UTF-8 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 UTFDataFormatException
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
.
- Parameters:
-
s
- the string value to be written. - Throws:
-
IOException
- if an I/O error occurs.