java.lang.Object | +--java.io.DataInput
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[] buf) This method reads raw bytes into the passed array until the array is full. |
void | readFully(byte[] buf, int offset, 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 |
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 |
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 skips and discards the specified number of bytes in an input stream |
public 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 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 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 << 8) + byte2)
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 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 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 void readFully(byte[] buf)
buf
- The buffer into which to read the dataEOFException
- If end of file is reached before filling the bufferIOException
- If any other error occurspublic void readFully(byte[] buf, int offset, 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.
buf
- The buffer into which to read the dataoffset
- 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 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 << 24) + (byte2 << 16) + (byte3 << 8) + byte4))
The value returned is in the range of -2147483648 to 2147483647.
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 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 long readLong()
long
value from an input stream
It operates by reading eight bytes from the stream and converting them to
a single Java 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)((byte1 << 56) + (byte2 << 48) + (byte3 << 40) +
(byte4 << 32) + (byte5 << 24) + (byte6 << 16) + (byte7 << 8) + byte9))
The value returned is in the range of -9223372036854775808 to 9223372036854775807.
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 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 << 8) + byte2)
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 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) + (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 \
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 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 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 << 8) + byte2)
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 int skipBytes(int n)
n
- The number of bytes to skipnum_bytes
EOFException
- If end of file is reached before all bytes can be
skippedIOException
- If any other error occurs