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.
DataInputStream is not necessarily safe for multithreaded access. Thread safety is optional and is the responsibility of users of methods in this class.
See Also
Inherited Field Summary
Public Constructor Summary
DataInputStream(InputStream in)
Creates a DataInputStream that uses the specified
underlying InputStream.
|
Public Method Summary
final int |
read(byte[] b)
Reads some number of bytes from the contained input stream and
stores them into the buffer array
b . |
final 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. |
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 . |
final double |
readDouble()
See the general contract of the
readDouble
method of DataInput . |
final 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 String |
readLine()
This method is deprecated.
This method does not properly convert bytes to characters.
As of JDK 1.1, the preferred way to read lines of text is via the
BufferedReader.readLine() method. Programs that use the
DataInputStream class to read lines can be converted to use
the BufferedReader class by replacing code of the form:
with:
|
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
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 . |
final int |
skipBytes(int n)
See the general contract of the
skipBytes
method of DataInput . |
Inherited Method Summary
Public Constructors
public DataInputStream (InputStream in)
Creates a DataInputStream that uses the specified underlying InputStream.
Parameters
in | the specified input stream |
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Public Methods
public final int read (byte[] b)
Reads some number of bytes from the contained input stream and
stores them into the buffer array 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)
Parameters
b | the buffer into which the data is read. |
---|
Returns
- the total number of bytes read into the buffer, or
-1
if there is no more data because the end of the stream has been reached.
Throws
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. |
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public final 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. 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.
Parameters
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. |
Returns
- the total number of bytes read into the buffer, or
-1
if there is no more data because the end of the stream has been reached.
Throws
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. |
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
boolean
value read.
Throws
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. |
See Also
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 | 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 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, interpreted as a
char
.
Throws
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. |
See Also
public final 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. |
public final 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. |
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Throws
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. |
See Also
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 | 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 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. |
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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 String readLine ()
This method is deprecated.
This method does not properly convert bytes to characters.
As of JDK 1.1, the preferred way to read lines of text is via the
BufferedReader.readLine()
method. Programs that use the
DataInputStream
class to read lines can be converted to use
the BufferedReader
class by replacing code of the form:
with: DataInputStream d = new DataInputStream(in);
BufferedReader d = new BufferedReader(new InputStreamReader(in));
See the general contract of the readLine
method of DataInput
.
Bytes for this operation are read from the contained input stream.
Returns
- the next line of text from this input stream.
Throws
IOException | if an I/O error occurs. |
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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 | 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 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 | 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 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 | 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. |
See Also
public static final 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
.
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 | 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. |
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 | 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 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 | 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 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 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. |
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