public class DataInputStream extends InputStream implements DataInput
DataInputStream is not necessarily safe for multithreaded access. Thread safety is optional and is the responsibility of users of methods in this class.
DataOutputStream
Modifier and Type | Field and Description |
---|---|
protected InputStream |
in
The input stream.
|
Constructor and Description |
---|
DataInputStream(InputStream in)
Creates a DataInputStream that uses the specified
underlying InputStream.
|
Modifier and Type | Method and Description |
---|---|
int |
available()
Returns an estimate of the number of bytes that can be read (or
skipped over) from this input stream without blocking by the next
caller of a method for this input stream.
|
void |
close()
Closes this input stream and releases any system resources
associated with the stream.
|
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. |
int |
read()
Reads the next byte of data from this input stream.
|
int |
read(byte[] b)
Reads some number of bytes from the contained input stream and
stores them into the buffer array
b . |
int |
read(byte[] b,
int off,
int len)
Reads up to
len bytes of data from the contained
input stream into an array of bytes. |
boolean |
readBoolean()
See the general contract of the
readBoolean
method of DataInput . |
byte |
readByte()
See the general contract of the
readByte
method of DataInput . |
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 . |
void |
readFully(byte[] b)
See the general contract of the
readFully
method of DataInput . |
void |
readFully(byte[] b,
int off,
int len)
See the general contract of the
readFully
method of DataInput . |
int |
readInt()
See the general contract of the
readInt
method of DataInput . |
long |
readLong()
See the general contract of the
readLong
method of DataInput . |
short |
readShort()
See the general contract of the
readShort
method of DataInput . |
int |
readUnsignedByte()
See the general contract of the
readUnsignedByte
method of DataInput . |
int |
readUnsignedShort()
See the general contract of the
readUnsignedShort
method of DataInput . |
String |
readUTF()
See the general contract of the
readUTF
method of DataInput . |
static String |
readUTF(DataInput in)
Reads from the
stream
in a representation
of a Unicode character string encoded in
modified UTF-8 format;
this string of characters is then returned as a String . |
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 this input
stream. |
int |
skipBytes(int n)
See the general contract of the
skipBytes
method of DataInput . |
protected volatile InputStream in
public DataInputStream(InputStream in)
in
- the specified input streampublic int available() throws IOException
This method returns the result of in
.available().
available
in class InputStream
IOException
- if an I/O error occurs.public void close() throws IOException
in.close()
.close
in interface Closeable
close
in interface AutoCloseable
close
in class InputStream
IOException
- if an I/O error occurs.public void mark(int readlimit)
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)
.
mark
in class InputStream
readlimit
- the maximum limit of bytes that can be read before
the mark position becomes invalid.InputStream.reset()
public boolean markSupported()
mark
and reset
methods.
This method
simply performs in.markSupported()
.markSupported
in class InputStream
true
if this stream type supports the
mark
and reset
method;
false
otherwise.InputStream.mark(int)
,
InputStream.reset()
public int read() throws IOException
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.
read
in class InputStream
-1
if the end of the
stream is reached.IOException
- if an I/O error occurs.public final int read(byte[] b) throws IOException
b
. The number of
bytes actually read is returned as an integer. This method blocks
until input data is available, end of file is detected, or an
exception is thrown.
If b
is null, a NullPointerException
is
thrown. If the length of b
is zero, then no bytes are
read and 0
is returned; otherwise, there is an attempt
to read at least one byte. If no byte is available because the
stream is at end of file, the value -1
is returned;
otherwise, at least one byte is read and stored into b
.
The first byte read is stored into element b[0]
, the
next one into b[1]
, and so on. The number of bytes read
is, at most, equal to the length of b
. Let k
be the number of bytes actually read; these bytes will be stored in
elements b[0]
through b[k-1]
, leaving
elements b[k]
through b[b.length-1]
unaffected.
The read(b)
method has the same effect as:
read(b, 0, b.length)
read
in class InputStream
b
- the buffer into which the data is read.-1
if there is no more data because the end
of the stream has been reached.IOException
- if the first byte cannot be read for any reason
other than end of file, the stream has been closed and the underlying
input stream does not support reading after close, or another I/O
error occurs.InputStream.read(byte[], int, int)
public final int read(byte[] b, int off, int len) throws IOException
len
bytes of data from the contained
input stream into an array of bytes. An attempt is made to read
as many as len
bytes, but a smaller number may be read,
possibly zero. The number of bytes actually read is returned as an
integer.
This method blocks until input data is available, end of file is detected, or an exception is thrown.
If len
is zero, then no bytes are read and
0
is returned; otherwise, there is an attempt to read at
least one byte. If no byte is available because the stream is at end of
file, the value -1
is returned; otherwise, at least one
byte is read and stored into b
.
The first byte read is stored into element b[off]
, the
next one into b[off+1]
, and so on. The number of bytes read
is, at most, equal to len
. Let k be the number of
bytes actually read; these bytes will be stored in elements
b[off]
through b[off+
k-1]
,
leaving elements b[off+
k]
through
b[off+len-1]
unaffected.
In every case, elements b[0]
through
b[off]
and elements b[off+len]
through
b[b.length-1]
are unaffected.
read
in class InputStream
b
- the buffer into which the data is read.off
- the start offset in the destination array b
len
- the maximum number of bytes read.-1
if there is no more data because the end
of the stream has been reached.NullPointerException
- If b
is null
.IndexOutOfBoundsException
- If off
is negative,
len
is negative, or len
is greater than
b.length - off
IOException
- if the first byte cannot be read for any reason
other than end of file, the stream has been closed and the underlying
input stream does not support reading after close, or another I/O
error occurs.InputStream.read(byte[], int, int)
public final boolean readBoolean() throws IOException
readBoolean
method of DataInput
.
Bytes for this operation are read from the contained input stream.
readBoolean
in interface DataInput
boolean
value read.EOFException
- if this input stream has reached the end.IOException
- the stream has been closed and the contained
input stream does not support reading after close, or
another I/O error occurs.public final byte readByte() throws IOException
readByte
method of DataInput
.
Bytes for this operation are read from the contained input stream.
readByte
in interface DataInput
byte
.EOFException
- if this input stream has reached the end.IOException
- the stream has been closed and the contained
input stream does not support reading after close, or
another I/O error occurs.public final char readChar() throws IOException
readChar
method of DataInput
.
Bytes for this operation are read from the contained input stream.
readChar
in interface DataInput
char
.EOFException
- if this input stream reaches the end before
reading two bytes.IOException
- the stream has been closed and the contained
input stream does not support reading after close, or
another I/O error occurs.public final double readDouble() throws IOException
readDouble
method of DataInput
.
Bytes for this operation are read from the contained input stream.
readDouble
in interface DataInput
double
.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.readLong()
,
Double.longBitsToDouble(long)
public final float readFloat() throws IOException
readFloat
method of DataInput
.
Bytes for this operation are read from the contained input stream.
readFloat
in interface DataInput
float
.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.readInt()
,
Float.intBitsToFloat(int)
public final void readFully(byte[] b) throws IOException
readFully
method of DataInput
.
Bytes for this operation are read from the contained input stream.
readFully
in interface DataInput
b
- the buffer into which the data is read.EOFException
- if this input stream reaches the end before
reading all the bytes.IOException
- the stream has been closed and the contained
input stream does not support reading after close, or
another I/O error occurs.public final void readFully(byte[] b, int off, int len) throws IOException
readFully
method of DataInput
.
Bytes for this operation are read from the contained input stream.
readFully
in interface DataInput
b
- the buffer into which the data is read.off
- the start offset of the data.len
- the number of bytes to read.EOFException
- if this input stream reaches the end before
reading all the bytes.IOException
- the stream has been closed and the contained
input stream does not support reading after close, or
another I/O error occurs.public final int readInt() throws IOException
readInt
method of DataInput
.
Bytes for this operation are read from the contained input stream.
readInt
in interface DataInput
int
.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.public final long readLong() throws IOException
readLong
method of DataInput
.
Bytes for this operation are read from the contained input stream.
readLong
in interface DataInput
long
.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.public final short readShort() throws IOException
readShort
method of DataInput
.
Bytes for this operation are read from the contained input stream.
readShort
in interface DataInput
EOFException
- if this input stream reaches the end before
reading two bytes.IOException
- the stream has been closed and the contained
input stream does not support reading after close, or
another I/O error occurs.public final int readUnsignedByte() throws IOException
readUnsignedByte
method of DataInput
.
Bytes for this operation are read from the contained input stream.
readUnsignedByte
in interface DataInput
EOFException
- if this input stream has reached the end.IOException
- the stream has been closed and the contained
input stream does not support reading after close, or
another I/O error occurs.public final int readUnsignedShort() throws IOException
readUnsignedShort
method of DataInput
.
Bytes for this operation are read from the contained input stream.
readUnsignedShort
in interface DataInput
EOFException
- if this input stream reaches the end before
reading two bytes.IOException
- the stream has been closed and the contained
input stream does not support reading after close, or
another I/O error occurs.public final String readUTF() throws IOException
readUTF
method of DataInput
.
Bytes for this operation are read from the contained input stream.
readUTF
in interface DataInput
EOFException
- if this input stream reaches the end before
reading all the bytes.IOException
- the stream has been closed and the contained
input stream does not support reading after close, or
another I/O error occurs.UTFDataFormatException
- if the bytes do not represent a valid
modified UTF-8 encoding of a string.readUTF(java.io.DataInput)
public static final String readUTF(DataInput in) throws IOException
in
a representation
of a Unicode character string encoded in
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
.in
- a data input stream.EOFException
- if the input stream reaches the end
before all the bytes.IOException
- the stream has been closed and the contained
input stream does not support reading after close, or
another I/O error occurs.UTFDataFormatException
- if the bytes do not represent a
valid modified UTF-8 encoding of a Unicode string.readUnsignedShort()
public void reset() throws IOException
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.
reset
in class InputStream
IOException
- if the stream has not been marked or if the
mark has been invalidated.InputStream.mark(int)
,
IOException
public long skip(long n) throws IOException
n
bytes of data from this input
stream. The skip
method may, for a variety of reasons, end
up skipping over some smaller number of bytes, possibly 0
.
This may result from any of a number of conditions; reaching end of file
before n
bytes have been skipped is only one possibility.
The actual number of bytes skipped is returned. If n
is
negative, the skip
method for class InputStream
always
returns 0, and no bytes are skipped. Subclasses may handle the negative
value differently.
The skip
method of this class creates a
byte array and then repeatedly reads into it until n
bytes
have been read or the end of the stream has been reached. Subclasses are
encouraged to provide a more efficient implementation of this method.
For instance, the implementation may depend on the ability to seek.
This method simply performs in.skip(n)
.
skip
in class InputStream
n
- the number of bytes to be skipped.IOException
- if the stream does not support seek,
or if some other I/O error occurs.public final int skipBytes(int n) throws IOException
skipBytes
method of DataInput
.
Bytes for this operation are read from the contained input stream.
skipBytes
in interface DataInput
n
- the number of bytes to be skipped.IOException
- if the contained input stream does not support
seek, or the stream has been closed and
the contained input stream does not support
reading after close, or another I/O error occurs.Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved. Use of this specification is subject to license terms.