public
class
DataInputStream
extends FilterInputStream
implements
DataInput
java.lang.Object | |||
↳ | java.io.InputStream | ||
↳ | java.io.FilterInputStream | ||
↳ | java.io.DataInputStream |
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 fields |
---|
From
class
java.io.FilterInputStream
|
Public constructors | |
---|---|
DataInputStream(InputStream in)
Creates a DataInputStream that uses the specified underlying InputStream. |
Public methods | |
---|---|
final
int
|
read(byte[] b)
Reads some number of bytes from the contained input stream and
stores them into the buffer array |
final
int
|
read(byte[] b, int off, int len)
Reads up to |
final
boolean
|
readBoolean()
See the general contract of the |
final
byte
|
readByte()
See the general contract of the |
final
char
|
readChar()
See the general contract of the |
final
double
|
readDouble()
See the general contract of the |
final
float
|
readFloat()
See the general contract of the |
final
void
|
readFully(byte[] b)
See the general contract of the |
final
void
|
readFully(byte[] b, int off, int len)
See the general contract of the |
final
int
|
readInt()
See the general contract of the |
final
String
|
readLine()
This method was deprecated
in API level 1.
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
|
final
long
|
readLong()
See the general contract of the |
final
short
|
readShort()
See the general contract of the |
final
String
|
readUTF()
See the general contract of the |
static
final
String
|
readUTF(DataInput in)
Reads from the
stream |
final
int
|
readUnsignedByte()
See the general contract of the |
final
int
|
readUnsignedShort()
See the general contract of the |
final
int
|
skipBytes(int n)
See the general contract of the |
Inherited methods | |
---|---|
From
class
java.io.FilterInputStream
| |
From
class
java.io.InputStream
| |
From
class
java.lang.Object
| |
From
interface
java.io.Closeable
| |
From
interface
java.io.DataInput
| |
From
interface
java.lang.AutoCloseable
|
DataInputStream (InputStream in)
Creates a DataInputStream that uses the specified underlying InputStream.
Parameters | |
---|---|
in |
InputStream :
the specified input stream
|
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 |
byte :
the buffer into which the data is read. |
Returns | |
---|---|
int |
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. |
See also:
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 |
byte :
the buffer into which the data is read. |
off |
int :
the start offset in the destination array b |
len |
int :
the maximum number of bytes read. |
Returns | |
---|---|
int |
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. |
See also:
boolean readBoolean ()
See the general contract of the readBoolean
method of DataInput
.
Bytes for this operation are read from the contained input stream.
Returns | |
---|---|
boolean |
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:
byte readByte ()
See the general contract of the readByte
method of DataInput
.
Bytes for this operation are read from the contained input stream.
Returns | |
---|---|
byte |
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:
char readChar ()
See the general contract of the readChar
method of DataInput
.
Bytes for this operation are read from the contained input stream.
Returns | |
---|---|
char |
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:
double readDouble ()
See the general contract of the readDouble
method of DataInput
.
Bytes for this operation are read from the contained input stream.
Returns | |
---|---|
double |
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:
float readFloat ()
See the general contract of the readFloat
method of DataInput
.
Bytes for this operation are read from the contained input stream.
Returns | |
---|---|
float |
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:
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 |
byte :
the buffer into which the data is 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:
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 |
byte :
the buffer into which the data is read. |
off |
int :
the start offset of the data. |
len |
int :
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:
int readInt ()
See the general contract of the readInt
method of DataInput
.
Bytes for this operation are read from the contained input stream.
Returns | |
---|---|
int |
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 |
the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs. |
See also:
String readLine ()
This method was deprecated
in API level 1.
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 | |
---|---|
String |
the next line of text from this input stream. |
Throws | |
---|---|
IOException |
if an I/O error occurs. |
See also:
long readLong ()
See the general contract of the readLong
method of DataInput
.
Bytes for this operation are read from the contained input stream.
Returns | |
---|---|
long |
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:
short readShort ()
See the general contract of the readShort
method of DataInput
.
Bytes for this operation are read from the contained input stream.
Returns | |
---|---|
short |
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:
String readUTF ()
See the general contract of the readUTF
method of DataInput
.
Bytes for this operation are read from the contained input stream.
Returns | |
---|---|
String |
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:
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 |
DataInput :
a data input stream. |
Returns | |
---|---|
String |
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:
int readUnsignedByte ()
See the general contract of the readUnsignedByte
method of DataInput
.
Bytes for this operation are read from the contained input stream.
Returns | |
---|---|
int |
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:
int readUnsignedShort ()
See the general contract of the readUnsignedShort
method of DataInput
.
Bytes for this operation are read from the contained input stream.
Returns | |
---|---|
int |
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:
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 |
int :
the number of bytes to be skipped. |
Returns | |
---|---|
int |
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. |