Class DataInputStream
- All Implemented Interfaces:
Closeable
,DataInput
,AutoCloseable
A DataInputStream is not safe for use by multiple concurrent threads. If a DataInputStream is to be used by more than one thread then access to the data input stream should be controlled by appropriate synchronization.
- Since:
- 1.0
- See Also:
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Field Summary
Fields inherited from class java.io.FilterInputStream
in
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Constructor Summary
ConstructorDescriptionCreates a DataInputStream that uses the specified underlying InputStream. -
Method Summary
Modifier and TypeMethodDescriptionfinal int
read
(byte[] b) Reads some number of bytes from the contained input stream and stores them into the buffer arrayb
.final int
read
(byte[] b, int off, int len) Reads up tolen
bytes of data from the contained input stream into an array of bytes.final boolean
See the general contract of thereadBoolean
method ofDataInput
.final byte
readByte()
See the general contract of thereadByte
method ofDataInput
.final char
readChar()
See the general contract of thereadChar
method ofDataInput
.final double
See the general contract of thereadDouble
method ofDataInput
.final float
See the general contract of thereadFloat
method ofDataInput
.final void
readFully
(byte[] b) See the general contract of thereadFully
method ofDataInput
.final void
readFully
(byte[] b, int off, int len) See the general contract of thereadFully
method ofDataInput
.final int
readInt()
See the general contract of thereadInt
method ofDataInput
.final String
readLine()
Deprecated.This method does not properly convert bytes to characters.final long
readLong()
See the general contract of thereadLong
method ofDataInput
.final short
See the general contract of thereadShort
method ofDataInput
.final int
See the general contract of thereadUnsignedByte
method ofDataInput
.final int
See the general contract of thereadUnsignedShort
method ofDataInput
.final String
readUTF()
See the general contract of thereadUTF
method ofDataInput
.static final String
Reads from the streamin
a representation of a Unicode character string encoded in modified UTF-8 format; this string of characters is then returned as aString
.final int
skipBytes
(int n) See the general contract of theskipBytes
method ofDataInput
.Methods inherited from class java.io.FilterInputStream
available, close, mark, markSupported, read, reset, skip
Methods inherited from class java.io.InputStream
nullInputStream, readAllBytes, readNBytes, readNBytes, skipNBytes, transferTo
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Constructor Details
-
DataInputStream
Creates a DataInputStream that uses the specified underlying InputStream.- Parameters:
in
- the specified input stream
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Method Details
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read
Reads some number of bytes from the contained input stream and stores them into the buffer arrayb
. 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, aNullPointerException
is thrown. If the length ofb
is zero, then no bytes are read and0
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 intob
.The first byte read is stored into element
b[0]
, the next one intob[1]
, and so on. The number of bytes read is, at most, equal to the length ofb
. Letk
be the number of bytes actually read; these bytes will be stored in elementsb[0]
throughb[k-1]
, leaving elementsb[k]
throughb[b.length-1]
unaffected.The
read(b)
method has the same effect as:read(b, 0, b.length)
- Overrides:
read
in classFilterInputStream
- 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.- See Also:
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read
Reads up tolen
bytes of data from the contained input stream into an array of bytes. An attempt is made to read as many aslen
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 and0
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 intob
.The first byte read is stored into element
b[off]
, the next one intob[off+1]
, and so on. The number of bytes read is, at most, equal tolen
. Let k be the number of bytes actually read; these bytes will be stored in elementsb[off]
throughb[off+
k-1]
, leaving elementsb[off+
k]
throughb[off+len-1]
unaffected.In every case, elements
b[0]
throughb[off]
and elementsb[off+len]
throughb[b.length-1]
are unaffected.- Overrides:
read
in classFilterInputStream
- Parameters:
b
- the buffer into which the data is read.off
- the start offset in the destination arrayb
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
- Ifb
isnull
.IndexOutOfBoundsException
- Ifoff
is negative,len
is negative, orlen
is greater thanb.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:
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readFully
See the general contract of thereadFully
method ofDataInput
.Bytes for this operation are read from the contained input stream.
- Specified by:
readFully
in interfaceDataInput
- Parameters:
b
- the buffer into which the data is read.- Throws:
NullPointerException
- ifb
isnull
.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:
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readFully
See the general contract of thereadFully
method ofDataInput
.Bytes for this operation are read from the contained input stream.
- Specified by:
readFully
in interfaceDataInput
- Parameters:
b
- the buffer into which the data is read.off
- the start offset in the data arrayb
.len
- the number of bytes to read.- Throws:
NullPointerException
- ifb
isnull
.IndexOutOfBoundsException
- ifoff
is negative,len
is negative, orlen
is greater thanb.length - off
.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:
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skipBytes
See the general contract of theskipBytes
method ofDataInput
.Bytes for this operation are read from the contained input stream.
- Specified by:
skipBytes
in interfaceDataInput
- 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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readBoolean
See the general contract of thereadBoolean
method ofDataInput
.Bytes for this operation are read from the contained input stream.
- Specified by:
readBoolean
in interfaceDataInput
- 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:
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readByte
See the general contract of thereadByte
method ofDataInput
.Bytes for this operation are read from the contained input stream.
- Specified by:
readByte
in interfaceDataInput
- 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:
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readUnsignedByte
See the general contract of thereadUnsignedByte
method ofDataInput
.Bytes for this operation are read from the contained input stream.
- Specified by:
readUnsignedByte
in interfaceDataInput
- 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:
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readShort
See the general contract of thereadShort
method ofDataInput
.Bytes for this operation are read from the contained input stream.
- Specified by:
readShort
in interfaceDataInput
- 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:
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readUnsignedShort
See the general contract of thereadUnsignedShort
method ofDataInput
.Bytes for this operation are read from the contained input stream.
- Specified by:
readUnsignedShort
in interfaceDataInput
- 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:
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readChar
See the general contract of thereadChar
method ofDataInput
.Bytes for this operation are read from the contained input stream.
- Specified by:
readChar
in interfaceDataInput
- 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:
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readInt
See the general contract of thereadInt
method ofDataInput
.Bytes for this operation are read from the contained input stream.
- Specified by:
readInt
in interfaceDataInput
- 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
- the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.- See Also:
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readLong
See the general contract of thereadLong
method ofDataInput
.Bytes for this operation are read from the contained input stream.
- Specified by:
readLong
in interfaceDataInput
- 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:
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readFloat
See the general contract of thereadFloat
method ofDataInput
.Bytes for this operation are read from the contained input stream.
- Specified by:
readFloat
in interfaceDataInput
- 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:
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readDouble
See the general contract of thereadDouble
method ofDataInput
.Bytes for this operation are read from the contained input stream.
- Specified by:
readDouble
in interfaceDataInput
- 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:
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readLine
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 theBufferedReader.readLine()
method. Programs that use theDataInputStream
class to read lines can be converted to use theBufferedReader
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 thereadLine
method ofDataInput
.Bytes for this operation are read from the contained input stream.
- Specified by:
readLine
in interfaceDataInput
- Returns:
- the next line of text from this input stream.
- Throws:
IOException
- if an I/O error occurs.- See Also:
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readUTF
See the general contract of thereadUTF
method ofDataInput
.Bytes for this operation are read from the contained input stream.
- Specified by:
readUTF
in interfaceDataInput
- 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:
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readUTF
Reads from the streamin
a representation of a Unicode character string encoded in modified UTF-8 format; this string of characters is then returned as aString
. The details of the modified UTF-8 representation are exactly the same as for thereadUTF
method ofDataInput
.- 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:
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