java.lang.Object | +--java.io.InputStream | +--java.io.FilterInputStream | +--java.io.DataInputStreamAll Implemented Interfaces:
DataInputStream(java.io.InputStream in) This constructor initializes a new |
int | read(byte[] b) This method reads bytes from the underlying stream into the specified byte array buffer. |
int | read(byte[] b, int off, int len) This method reads bytes from the underlying stream into the specified byte array buffer. |
boolean | readBoolean() This method reads a Java boolean value from an input stream. |
byte | readByte() This method reads a Java byte value from an input stream. |
char | readChar() This method reads a Java |
double | readDouble() This method reads a Java double value from an input stream. |
float | readFloat() This method reads a Java float value from an input stream. |
void | readFully(byte[] b) This method reads raw bytes into the passed array until the array is full. |
void | readFully(byte[] b, int off, int len) This method reads raw bytes into the passed array |
int | readInt() This method reads a Java |
java.lang.String | readLine() This method reads the next line of text data from an input stream. |
long | readLong() This method reads a Java long value from an input stream
It operates by reading eight bytes from the stream and converting them to
a single Java |
short | readShort() This method reads a signed 16-bit value into a Java in from the stream. |
java.lang.String | readUTF() This method reads a |
static java.lang.String | readUTF(java.io.DataInput in) This method reads a String encoded in UTF-8 format from the
specified |
int | readUnsignedByte() This method reads 8 unsigned bits into a Java |
int | readUnsignedShort() This method reads 16 unsigned bits into a Java int value from the stream. |
int | skipBytes(int n) This method attempts to skip and discard the specified number of bytes in the input stream. |
public DataInputStream(java.io.InputStream in)
DataInputStream
to read from the specified subordinate stream.
in
- The subordinate InputStream
to read frompublic final int read(byte[] b)
b
- The buffer into which bytes will be read.IOException
- If an error occurs.public final int read(byte[] b, int off, int len)
len
bytes and
will start storing them at position off
into the buffer.
This method can return a short count if there is insufficient data
remaining to be read to complete the desired read length.
b
- The buffer into which bytes will be read.off
- The offset into the buffer to start storing bytes.len
- The requested number of bytes to read.IOException
- If an error occurs.public final boolean readBoolean()
false
. If the byte is non-zero, then
the value returned is true
.
This method can read a boolean
written by an object
implementing the writeBoolean()
method in the
DataOutput
interface.
boolean
value readEOFException
- If end of file is reached before reading
the booleanIOException
- If any other error occurspublic final byte readByte()
This method can read a byte
written by an object
implementing the writeByte()
method in the
DataOutput
interface.
byte
value readEOFException
- If end of file is reached before reading the byteIOException
- If any other error occurspublic final char readChar()
char
value from an input stream.
It operates by reading two bytes from the stream and converting them to
a single 16-bit Java char
. The two bytes are stored most
significant byte first (i.e., "big endian") regardless of the native
host byte ordering.
As an example, if byte1
and byte2
represent the first and second byte read from the stream
respectively, they will be transformed to a char
in
the following manner:
(char)(((byte1 & 0xFF) << 8) | (byte2 & 0xFF)
This method can read a char
written by an object
implementing the writeChar()
method in the
DataOutput
interface.
char
value readEOFException
- If end of file is reached before reading the charIOException
- If any other error occurspublic final double readDouble()
long
value from the stream by calling the
readLong()
method in this interface, then converts
that long
to a double
using the
longBitsToDouble
method in the class
java.lang.Double
This method can read a double
written by an object
implementing the writeDouble()
method in the
DataOutput
interface.
double
value readEOFException
- If end of file is reached before reading
the doubleIOException
- If any other error occursjava.lang.Double
DataOutput
public final float readFloat()
int
value from the
stream by calling the readInt()
method in this
interface, then converts that int
to a
float
using the intBitsToFloat
method
in the class java.lang.Float
This method can read a float
written by an object
implementing the * writeFloat()
method in the
DataOutput
interface.
float
value readEOFException
- If end of file is reached before reading the floatIOException
- If any other error occursjava.lang.Float
DataOutput
public final void readFully(byte[] b)
b
- The buffer into which to read the dataEOFException
- If end of file is reached before filling
the bufferIOException
- If any other error occurspublic final void readFully(byte[] b, int off, int len)
buf
starting offset
bytes into the
buffer. The number of bytes read will be exactly
len
Note that this method blocks until the data is
available and * throws an exception if there is not enough data
left in the stream to read len
bytes.
b
- The buffer into which to read the dataoff
- The offset into the buffer to start storing datalen
- The number of bytes to read into the bufferEOFException
- If end of file is reached before filling
the bufferIOException
- If any other error occurspublic final int readInt()
int
value from an input
stream It operates by reading four bytes from the stream and
converting them to a single Java int
The bytes are
stored most significant byte first (i.e., "big endian")
regardless of the native host byte ordering.
As an example, if byte1
through byte4
represent the first four bytes read from the stream, they will be
transformed to an int
in the following manner:
(int)(((byte1 & 0xFF) << 24) + ((byte2 & 0xFF) << 16) +
((byte3 & 0xFF) << 8) + (byte4 & 0xFF)))
The value returned is in the range of 0 to 65535.
This method can read an int
written by an object
implementing the writeInt()
method in the
DataOutput
interface.
int
value readEOFException
- If end of file is reached before reading the intIOException
- If any other error occurspublic final String readLine()
char
values by treating the byte read as the low
eight bits of the char
and using 0 as the high eight
bits. Because of this, it does not support the full 16-bit
Unicode character set.
The reading of bytes ends when either the end of file or a line
terminator is encountered. The bytes read are then returned as a
String
A line terminator is a byte sequence
consisting of either \r
, \n
or
\r\n
. These termination charaters are discarded and
are not returned as part of the string.
This method can read data that was written by an object implementing the
writeLine()
method in DataOutput
.
String
IOException
- If an error occurspublic final long readLong()
long
The bytes are stored most
significant byte first (i.e., "big endian") regardless of the native
host byte ordering.
As an example, if byte1
through byte8
represent the first eight bytes read from the stream, they will
be transformed to an long
in the following manner:
(long)((((long)byte1 & 0xFF) << 56) + (((long)byte2 & 0xFF) << 48) +
(((long)byte3 & 0xFF) << 40) + (((long)byte4 & 0xFF) << 32) +
(((long)byte5 & 0xFF) << 24) + (((long)byte6 & 0xFF) << 16) +
(((long)byte7 & 0xFF) << 8) + ((long)byte9 & 0xFF)))
The value returned is in the range of 0 to 65535.
This method can read an long
written by an object
implementing the writeLong()
method in the
DataOutput
interface.
long
value readEOFException
- If end of file is reached before reading the longIOException
- If any other error occurspublic final short readShort()
short
. The
two bytes are stored most significant byte first (i.e., "big
endian") regardless of the native host byte ordering.
As an example, if byte1
and byte2
represent the first and second byte read from the stream
respectively, they will be transformed to a short
. in
the following manner:
(short)(((byte1 & 0xFF) << 8) | (byte2 & 0xFF)
The value returned is in the range of -32768 to 32767.
This method can read a short
written by an object
implementing the writeShort()
method in the
DataOutput
interface.
short
value readEOFException
- If end of file is reached before reading the valueIOException
- If any other error occurspublic final String readUTF()
String
from an input stream that
is encoded in a modified UTF-8 format. This format has a leading
two byte sequence that contains the remaining number of bytes to
read. This two byte sequence is read using the
readUnsignedShort()
method of this interface.
After the number of remaining bytes have been determined, these
bytes are read an transformed into char
values.
These char
values are encoded in the stream using
either a one, two, or three byte format. The particular format
in use can be determined by examining the first byte read.
If the first byte has a high order bit of 0, then that character
consists on only one byte. This character value consists of
seven bits that are at positions 0 through 6 of the byte. As an
example, if byte1
is the byte read from the stream,
it would be converted to a char
like so:
(char)byte1
If the first byte has 110 as its high order bits, then the character consists of two bytes. The bits that make up the character value are in positions 0 through 4 of the first byte and bit positions 0 through 5 of the second byte. (The second byte should have 10 as its high order bits). These values are in most significant byte first (i.e., "big endian") order.
As an example, if byte1
and byte2
are
the first two bytes read respectively, and the high order bits of
them match the patterns which indicate a two byte character
encoding, then they would be converted to a Java
char
like so:
(char)(((byte1 & 0x1F) << 6) | (byte2 & 0x3F))
If the first byte has a 1110 as its high order bits, then the character consists of three bytes. The bits that make up the character value are in positions 0 through 3 of the first byte and bit positions 0 through 5 of the other two bytes. (The second and third bytes should have 10 as their high order bits). These values are in most significant byte first (i.e., "big endian") order.
As an example, if byte1
byte2
and
byte3
are the three bytes read, and the high order
bits of them match the patterns which indicate a three byte
character encoding, then they would be converted to a Java
char
like so:
(char)(((byte1 & 0x0F) << 12) | ((byte2 & 0x3F) << 6) | (byte3 & 0x3F))
Note that all characters are encoded in the method that requires
the fewest number of bytes with the exception of the character
with the value of \u0000
which is encoded as two
bytes. This is a modification of the UTF standard used to
prevent C language style NUL
values from appearing
in the byte stream.
This method can read data that was written by an object implementing the
writeUTF()
method in DataOutput
EOFException
- If end of file is reached before reading
the StringUTFDataFormatException
- If the data is not in UTF-8 formatIOException
- If any other error occurspublic static final String readUTF(java.io.DataInput in)
DataInput
source.
in
- The DataInput
source to read fromIOException
- If an error occurspublic final int readUnsignedByte()
int
value from the stream. The value returned is in the range of 0 to
255.
This method can read an unsigned byte written by an object
implementing the writeUnsignedByte()
method in the
DataOutput
interface.
int
.EOFException
- If end of file is reached before reading the valueIOException
- If any other error occurspublic final int readUnsignedShort()
int
The two bytes are stored most
significant byte first (i.e., "big endian") regardless of the native
host byte ordering.
As an example, if byte1
and byte2
represent the first and second byte read from the stream
respectively, they will be transformed to an int
in
the following manner:
(int)(((byte1 & 0xFF) << 8) + (byte2 & 0xFF))
The value returned is in the range of 0 to 65535.
This method can read an unsigned short written by an object
implementing the writeUnsignedShort()
method in the
DataOutput
interface.
int
EOFException
- If end of file is reached before reading the valueIOException
- If any other error occurspublic final int skipBytes(int n)
n
- The requested number of bytes to skip.IOException
- If an error occurs.
FilteredInputStream
implements theDataInput
interface that provides method for reading primitive Java data types from a stream.