| java.lang.Object | ||
| ↳ | java.io.InputStream | |
| ↳ | java.io.DataInputStream | |
Class Overview
A data input stream lets an application read primitive Java data types from an underlying input stream in a machine-independent way. An application uses a data output stream to write data that can later be read by a data input stream.
See Also
Summary
| Fields | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| protected InputStream | in | The input stream. | |||||||||
| Public Constructors | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
|
DataInputStream(InputStream in)
Creates a
DataInputStream and saves its argument, the input
stream in, for later use. | |||||||||||
| Public Methods | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| int |
available()
Returns the number of bytes that can be read from this input stream without
blocking.
| ||||||||||
| void |
close()
Closes this input stream and releases any system resources associated with
the stream.
| ||||||||||
| synchronized void |
mark(int readlimit)
Marks the current position in this input stream.
| ||||||||||
| boolean |
markSupported()
Tests if this input stream supports the
mark and
reset methods. | ||||||||||
| final int |
read(byte[] b)
See the general contract of the
read method of
DataInput. | ||||||||||
| int |
read()
Reads the next byte of data from this input stream.
| ||||||||||
| final int |
read(byte[] b, int off, int len)
Reads up to
len bytes of data from this input stream into an
array of bytes. | ||||||||||
| final boolean |
readBoolean()
See the general contract of the
readBoolean method of
DataInput. | ||||||||||
| final byte |
readByte()
See the general contract of the
readByte method of
DataInput. | ||||||||||
| final char |
readChar()
See the general contract of the
readChar method of
DataInput. | ||||||||||
| double |
readDouble()
See the general contract of the
readDouble method of
DataInput. | ||||||||||
| float |
readFloat()
See the general contract of the
readFloat method of
DataInput. | ||||||||||
| final void |
readFully(byte[] b)
See the general contract of the
readFully method of
DataInput. | ||||||||||
| final void |
readFully(byte[] b, int off, int len)
See the general contract of the
readFully method of
DataInput. | ||||||||||
| final int |
readInt()
See the general contract of the
readInt method of
DataInput. | ||||||||||
| final long |
readLong()
See the general contract of the
readLong method of
DataInput. | ||||||||||
| final short |
readShort()
See the general contract of the
readShort method of
DataInput. | ||||||||||
| final String |
readUTF()
See the general contract of the
readUTF method of
DataInput. | ||||||||||
| final static String |
readUTF(DataInput in)
Reads from the stream
in a representation of a Unicode character
string encoded in Java modified UTF-8 format; this string of characters is
then returned as a String. | ||||||||||
| final int |
readUnsignedByte()
See the general contract of the
readUnsignedByte method of
DataInput. | ||||||||||
| final int |
readUnsignedShort()
See the general contract of the
readUnsignedShort method of
DataInput. | ||||||||||
| synchronized void |
reset()
Repositions this stream to the position at the time the
mark
method was last called on this input stream. | ||||||||||
| long |
skip(long n)
Skips over and discards
n bytes of data from the input stream. | ||||||||||
| final int |
skipBytes(int n)
See the general contract of the
skipBytes method of
DataInput. | ||||||||||
|
[Expand]
Inherited Methods | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
From class
java.io.InputStream
| |||||||||||
|
From class
java.lang.Object
| |||||||||||
|
From interface
java.io.DataInput
| |||||||||||
Fields
Public Constructors
public DataInputStream (InputStream in)
Creates a DataInputStream and saves its argument, the input
stream in, for later use.
Parameters
| in | the input stream. |
|---|
Public Methods
public int available ()
Returns the number of bytes that can be read from this input stream without blocking.
This method simply performs in.available(n) and returns the
result.
Returns
- the number of bytes that can be read from the input stream without blocking.
Throws
| IOException | if an I/O error occurs. |
|---|
public void close ()
Closes this input stream and releases any system resources associated with
the stream. This method simply performs in.close().
Throws
| IOException | if an I/O error occurs. |
|---|
public synchronized void mark (int readlimit)
Marks the current position in this input stream. A subsequent call to the
reset method repositions this stream at the last marked position
so that subsequent reads re-read the same bytes.
The readlimit argument tells this input stream to allow that
many bytes to be read before the mark position gets invalidated.
This method simply performs in.mark(readlimit).
Parameters
| readlimit | the maximum limit of bytes that can be read before the mark position becomes invalid. |
|---|
public boolean markSupported ()
Tests if this input stream supports the mark and
reset methods. This method simply performs
in.markSupported().
Returns
trueif this stream type supports themarkandresetmethod;falseotherwise.
public final int read (byte[] b)
See the general contract of the read method of
DataInput.
Bytes for this operation are read from the contained input stream.
Parameters
| b | the buffer into which the data is read. |
|---|
Returns
- the total number of bytes read into the buffer, or
-1if there is no more data because the end of the stream has been reached.
Throws
| IOException | if an I/O error occurs. |
|---|
See Also
public int read ()
Reads the next byte of data from this input stream. The value byte is
returned as an int in the range 0 to
255. If no byte is available because the end of the stream has
been reached, the value -1 is returned. This method blocks until
input data is available, the end of the stream is detected, or an exception
is thrown.
This method simply performs in.read() and returns the result.
Returns
- the next byte of data, or
-1if the end of the stream is reached.
Throws
| IOException | if an I/O error occurs. |
|---|
public final int read (byte[] b, int off, int len)
Reads up to len bytes of data from this input stream into an
array of bytes. This method blocks until some input is available.
This method simply performs in.read(b, off, len) and returns the
result.
Parameters
| b | the buffer into which the data is read. |
|---|---|
| off | the start offset of the data. |
| len | the maximum number of bytes read. |
Returns
- the total number of bytes read into the buffer, or
-1if there is no more data because the end of the stream has been reached.
Throws
| IOException | if an I/O error occurs. |
|---|
public final boolean readBoolean ()
See the general contract of the readBoolean method of
DataInput.
Bytes for this operation are read from the contained input stream.
Returns
- the
booleanvalue read.
Throws
| EOFException | if this input stream has reached the end. |
|---|---|
| IOException | if an I/O error occurs. |
public final byte readByte ()
See the general contract of the readByte method of
DataInput.
Bytes for this operation are read from the contained input stream.
Returns
- the next byte of this input stream as a signed 8-bit
byte.
Throws
| EOFException | if this input stream has reached the end. |
|---|---|
| IOException | if an I/O error occurs. |
public final char readChar ()
See the general contract of the readChar method of
DataInput.
Bytes for this operation are read from the contained input stream.
Returns
- the next two bytes of this input stream as a Unicode character.
Throws
| EOFException | if this input stream reaches the end before reading two bytes. |
|---|---|
| IOException | if an I/O error occurs. |
public double readDouble ()
See the general contract of the readDouble method of
DataInput.
Bytes for this operation are read from the contained input stream.
Returns
- the next eight bytes of this input stream, interpreted as a
double.
Throws
| EOFException | if this input stream reaches the end before reading eight bytes. |
|---|---|
| IOException | the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs. |
See Also
public float readFloat ()
See the general contract of the readFloat method of
DataInput.
Bytes for this operation are read from the contained input stream.
Returns
- the next four bytes of this input stream, interpreted as a
float.
Throws
| EOFException | if this input stream reaches the end before reading four bytes. |
|---|---|
| IOException | the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs. |
See Also
public final void readFully (byte[] b)
See the general contract of the readFully method of
DataInput.
Bytes for this operation are read from the contained input stream.
Parameters
| b | the buffer into which the data is read. |
|---|
Throws
| EOFException | if this input stream reaches the end before reading all the bytes. |
|---|---|
| IOException | if an I/O error occurs. |
public final void readFully (byte[] b, int off, int len)
See the general contract of the readFully method of
DataInput.
Bytes for this operation are read from the contained input stream.
Parameters
| b | the buffer into which the data is read. |
|---|---|
| off | the start offset of the data. |
| len | the number of bytes to read. |
Throws
| EOFException | if this input stream reaches the end before reading all the bytes. |
|---|---|
| IOException | if an I/O error occurs. |
public final int readInt ()
See the general contract of the readInt method of
DataInput.
Bytes for this operation are read from the contained input stream.
Returns
- the next four bytes of this input stream, interpreted as an
int.
Throws
| EOFException | if this input stream reaches the end before reading four bytes. |
|---|---|
| IOException | if an I/O error occurs. |
public final long readLong ()
See the general contract of the readLong method of
DataInput.
Bytes for this operation are read from the contained input stream.
Returns
- the next eight bytes of this input stream, interpreted as a
long.
Throws
| EOFException | if this input stream reaches the end before reading eight bytes. |
|---|---|
| IOException | if an I/O error occurs. |
public final short readShort ()
See the general contract of the readShort method of
DataInput.
Bytes for this operation are read from the contained input stream.
Returns
- the next two bytes of this input stream, interpreted as a signed 16-bit number.
Throws
| EOFException | if this input stream reaches the end before reading two bytes. |
|---|---|
| IOException | if an I/O error occurs. |
public final String readUTF ()
See the general contract of the readUTF method of
DataInput.
Bytes for this operation are read from the contained input stream.
Returns
- a Unicode string.
Throws
| EOFException | if this input stream reaches the end before reading all the bytes. |
|---|---|
| IOException | if an I/O error occurs. |
See Also
public static final String readUTF (DataInput in)
Reads from the stream in a representation of a Unicode character
string encoded in Java modified UTF-8 format; this string of characters is
then returned as a String. The details of the modified UTF-8
representation are exactly the same as for the readUTF method of
DataInput.
Parameters
| in | a data input stream. |
|---|
Returns
- a Unicode string.
Throws
| EOFException | if the input stream reaches the end before all the bytes. |
|---|---|
| IOException | if an I/O error occurs. |
| UTFDataFormatException | if the bytes do not represent a valid UTF-8 encoding of a Unicode string. |
See Also
public final int readUnsignedByte ()
See the general contract of the readUnsignedByte method of
DataInput.
Bytes for this operation are read from the contained input stream.
Returns
- the next byte of this input stream, interpreted as an unsigned 8-bit number.
Throws
| EOFException | if this input stream has reached the end. |
|---|---|
| IOException | if an I/O error occurs. |
public final int readUnsignedShort ()
See the general contract of the readUnsignedShort method of
DataInput.
Bytes for this operation are read from the contained input stream.
Returns
- the next two bytes of this input stream, interpreted as an unsigned 16-bit integer.
Throws
| EOFException | if this input stream reaches the end before reading two bytes. |
|---|---|
| IOException | if an I/O error occurs. |
public synchronized void reset ()
Repositions this stream to the position at the time the mark
method was last called on this input stream.
This method simply performs in.reset().
Stream marks are intended to be used in situations where you need to read ahead a little to see what's in the stream. Often this is most easily done by invoking some general parser. If the stream is of the type handled by the parse, it just chugs along happily. If the stream is not of that type, the parser should toss an exception when it fails. If this happens within readlimit bytes, it allows the outer code to reset the stream and try another parser.
Throws
| IOException | if the stream has not been marked or if the mark has been invalidated. |
|---|
public long skip (long n)
Skips over and discards n bytes of data from the input stream.
The skip method may, for a variety of reasons, end up skipping
over some smaller number of bytes, possibly 0. The actual number
of bytes skipped is returned.
This method simply performs in.skip(n).
Parameters
| n | the number of bytes to be skipped. |
|---|
Returns
- the actual number of bytes skipped.
Throws
| IOException | if an I/O error occurs. |
|---|
public final int skipBytes (int n)
See the general contract of the skipBytes method of
DataInput.
Bytes for this operation are read from the contained input stream.
Parameters
| n | the number of bytes to be skipped. |
|---|
Returns
- the actual number of bytes skipped.
Throws
| IOException | if an I/O error occurs. |
|---|