Class DataOutputStream
- java.lang.Object
-
- java.io.OutputStream
-
- java.io.FilterOutputStream
-
- java.io.DataOutputStream
- All Implemented Interfaces:
-
Closeable
,DataOutput
,Flushable
,AutoCloseable
public class DataOutputStream extends FilterOutputStream implements DataOutput
A data output stream lets an application write primitive Java data types to an output stream in a portable way. An application can then use a data input stream to read the data back in.
- Since:
- 1.0
- See Also:
DataInputStream
Field Summary
Modifier and Type | Field | Description |
---|---|---|
protected int | written | The number of bytes written to the data output stream so far. |
Fields declared in class java.io.FilterOutputStream
out
Constructor Summary
Constructor | Description |
---|---|
DataOutputStream(OutputStream out) | Creates a new data output stream to write data to the specified underlying output stream. |
Method Summary
Modifier and Type | Method | Description |
---|---|---|
void | flush() | Flushes this data output stream. |
int | size() | Returns the current value of the counter |
void | write(byte[] b,
int off,
int len) | Writes |
void | write(int b) | Writes the specified byte (the low eight bits of the argument |
void | writeBoolean(boolean v) | Writes a |
void | writeByte(int v) | Writes out a |
void | writeBytes(String s) | Writes out the string to the underlying output stream as a sequence of bytes. |
void | writeChar(int v) | Writes a |
void | writeChars(String s) | Writes a string to the underlying output stream as a sequence of characters. |
void | writeDouble(double v) | Converts the double argument to a |
void | writeFloat(float v) | Converts the float argument to an |
void | writeInt(int v) | Writes an |
void | writeLong(long v) | Writes a |
void | writeShort(int v) | Writes a |
void | writeUTF(String str) | Writes a string to the underlying output stream using modified UTF-8 encoding in a machine-independent manner. |
Methods declared in class java.io.FilterOutputStream
close, write
Methods declared in class java.io.OutputStream
nullOutputStream
Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Methods declared in interface java.io.DataOutput
write
Field Detail
written
protected int written
The number of bytes written to the data output stream so far. If this counter overflows, it will be wrapped to Integer.MAX_VALUE.
Constructor Detail
DataOutputStream
public DataOutputStream(OutputStream out)
Creates a new data output stream to write data to the specified underlying output stream. The counter written
is set to zero.
- Parameters:
-
out
- the underlying output stream, to be saved for later use. - See Also:
FilterOutputStream.out
Method Detail
write
public void write(int b) throws IOException
Writes the specified byte (the low eight bits of the argument b
) to the underlying output stream. If no exception is thrown, the counter written
is incremented by 1
.
Implements the write
method of OutputStream
.
- Specified by:
-
write
in interfaceDataOutput
- Overrides:
-
write
in classFilterOutputStream
- Parameters:
-
b
- thebyte
to be written. - Throws:
-
IOException
- if an I/O error occurs. - See Also:
FilterOutputStream.out
write
public void write(byte[] b, int off, int len) throws IOException
Writes len
bytes from the specified byte array starting at offset off
to the underlying output stream. If no exception is thrown, the counter written
is incremented by len
.
- Specified by:
-
write
in interfaceDataOutput
- Overrides:
-
write
in classFilterOutputStream
- 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. - See Also:
FilterOutputStream.out
flush
public void flush() throws IOException
Flushes this data output stream. This forces any buffered output bytes to be written out to the stream.
The flush
method of DataOutputStream
calls the flush
method of its underlying output stream.
- Specified by:
-
flush
in interfaceFlushable
- Overrides:
-
flush
in classFilterOutputStream
- Throws:
-
IOException
- if an I/O error occurs. - See Also:
-
FilterOutputStream.out
,OutputStream.flush()
writeBoolean
public final void writeBoolean(boolean v) throws IOException
Writes a boolean
to the underlying output stream as a 1-byte value. The value true
is written out as the value (byte)1
; the value false
is written out as the value (byte)0
. If no exception is thrown, the counter written
is incremented by 1
.
- Specified by:
-
writeBoolean
in interfaceDataOutput
- Parameters:
-
v
- aboolean
value to be written. - Throws:
-
IOException
- if an I/O error occurs. - See Also:
FilterOutputStream.out
writeByte
public final void writeByte(int v) throws IOException
Writes out a byte
to the underlying output stream as a 1-byte value. If no exception is thrown, the counter written
is incremented by 1
.
- Specified by:
-
writeByte
in interfaceDataOutput
- Parameters:
-
v
- abyte
value to be written. - Throws:
-
IOException
- if an I/O error occurs. - See Also:
FilterOutputStream.out
writeShort
public final void writeShort(int v) throws IOException
Writes a short
to the underlying output stream as two bytes, high byte first. If no exception is thrown, the counter written
is incremented by 2
.
- Specified by:
-
writeShort
in interfaceDataOutput
- Parameters:
-
v
- ashort
to be written. - Throws:
-
IOException
- if an I/O error occurs. - See Also:
FilterOutputStream.out
writeChar
public final void writeChar(int v) throws IOException
Writes a char
to the underlying output stream as a 2-byte value, high byte first. If no exception is thrown, the counter written
is incremented by 2
.
- Specified by:
-
writeChar
in interfaceDataOutput
- Parameters:
-
v
- achar
value to be written. - Throws:
-
IOException
- if an I/O error occurs. - See Also:
FilterOutputStream.out
writeInt
public final void writeInt(int v) throws IOException
Writes an int
to the underlying output stream as four bytes, high byte first. If no exception is thrown, the counter written
is incremented by 4
.
- Specified by:
-
writeInt
in interfaceDataOutput
- Parameters:
-
v
- anint
to be written. - Throws:
-
IOException
- if an I/O error occurs. - See Also:
FilterOutputStream.out
writeLong
public final void writeLong(long v) throws IOException
Writes a long
to the underlying output stream as eight bytes, high byte first. In no exception is thrown, the counter written
is incremented by 8
.
- Specified by:
-
writeLong
in interfaceDataOutput
- Parameters:
-
v
- along
to be written. - Throws:
-
IOException
- if an I/O error occurs. - See Also:
FilterOutputStream.out
writeFloat
public final void writeFloat(float v) throws IOException
Converts the float argument to an int
using the floatToIntBits
method in class Float
, and then writes that int
value to the underlying output stream as a 4-byte quantity, high byte first. If no exception is thrown, the counter written
is incremented by 4
.
- Specified by:
-
writeFloat
in interfaceDataOutput
- Parameters:
-
v
- afloat
value to be written. - Throws:
-
IOException
- if an I/O error occurs. - See Also:
-
FilterOutputStream.out
,Float.floatToIntBits(float)
writeDouble
public final void writeDouble(double v) throws IOException
Converts the double argument to a long
using the doubleToLongBits
method in class Double
, and then writes that long
value to the underlying output stream as an 8-byte quantity, high byte first. If no exception is thrown, the counter written
is incremented by 8
.
- Specified by:
-
writeDouble
in interfaceDataOutput
- Parameters:
-
v
- adouble
value to be written. - Throws:
-
IOException
- if an I/O error occurs. - See Also:
-
FilterOutputStream.out
,Double.doubleToLongBits(double)
writeBytes
public final void writeBytes(String s) throws IOException
Writes out the string to the underlying output stream as a sequence of bytes. Each character in the string is written out, in sequence, by discarding its high eight bits. If no exception is thrown, the counter written
is incremented by the length of s
.
- Specified by:
-
writeBytes
in interfaceDataOutput
- Parameters:
-
s
- a string of bytes to be written. - Throws:
-
IOException
- if an I/O error occurs. - See Also:
FilterOutputStream.out
writeChars
public final void writeChars(String s) throws IOException
Writes a string to the underlying output stream as a sequence of characters. Each character is written to the data output stream as if by the writeChar
method. If no exception is thrown, the counter written
is incremented by twice the length of s
.
- Specified by:
-
writeChars
in interfaceDataOutput
- Parameters:
-
s
- aString
value to be written. - Throws:
-
IOException
- if an I/O error occurs. - See Also:
-
writeChar(int)
,FilterOutputStream.out
writeUTF
public final void writeUTF(String str) throws IOException
Writes a string to the underlying output stream using modified UTF-8 encoding in a machine-independent manner.
First, two bytes are written to the output stream as if by the writeShort
method giving the number of bytes to follow. This value is the number of bytes actually written out, not the length of the string. Following the length, each character of the string is output, in sequence, using the modified UTF-8 encoding for the character. If no exception is thrown, the counter written
is incremented by the total number of bytes written to the output stream. This will be at least two plus the length of str
, and at most two plus thrice the length of str
.
- Specified by:
-
writeUTF
in interfaceDataOutput
- Parameters:
-
str
- a string to be written. - Throws:
-
IOException
- if an I/O error occurs.
size
public final int size()
Returns the current value of the counter written
, the number of bytes written to this data output stream so far. If the counter overflows, it will be wrapped to Integer.MAX_VALUE.
- Returns:
- the value of the
written
field. - See Also:
written