@Beta @GwtIncompatible public final class LittleEndianDataInputStream extends java.io.FilterInputStream implements java.io.DataInput
DataInput
that uses little-endian byte ordering for reading short
, int
, float
, double
, and long
values.
Note: This class intentionally violates the specification of its supertype DataInput
, which explicitly requires big-endian byte order.
Constructor and Description |
---|
LittleEndianDataInputStream(java.io.InputStream in)
Creates a
LittleEndianDataInputStream that wraps the given stream. |
Modifier and Type | Method and Description |
---|---|
boolean |
readBoolean()
Reads one input byte and returns
true if that byte is nonzero,
false if that byte is zero. |
byte |
readByte()
Reads and returns one input byte.
|
char |
readChar()
Reads a char as specified by
DataInputStream.readChar() , except using little-endian
byte order. |
double |
readDouble()
Reads a
double as specified by DataInputStream.readDouble() , except using
little-endian byte order. |
float |
readFloat()
Reads a
float as specified by DataInputStream.readFloat() , except using
little-endian byte order. |
void |
readFully(byte[] b)
Reads some bytes from an input
stream and stores them into the buffer
array
b . |
void |
readFully(byte[] b,
int off,
int len)
Reads
len
bytes from
an input stream. |
int |
readInt()
Reads an integer as specified by
DataInputStream.readInt() , except using little-endian
byte order. |
java.lang.String |
readLine()
This method will throw an
UnsupportedOperationException . |
long |
readLong()
Reads a
long as specified by DataInputStream.readLong() , except using
little-endian byte order. |
short |
readShort()
Reads a
short as specified by DataInputStream.readShort() , except using
little-endian byte order. |
int |
readUnsignedByte()
Reads one input byte, zero-extends
it to type
int , and returns
the result, which is therefore in the range
0
through 255 . |
int |
readUnsignedShort()
Reads an unsigned
short as specified by DataInputStream.readUnsignedShort() ,
except using little-endian byte order. |
java.lang.String |
readUTF()
Reads in a string that has been encoded using a
modified UTF-8
format.
|
int |
skipBytes(int n)
Makes an attempt to skip over
n bytes
of data from the input
stream, discarding the skipped bytes. |
public LittleEndianDataInputStream(java.io.InputStream in)
LittleEndianDataInputStream
that wraps the given stream.in
- the stream to delegate to@CanIgnoreReturnValue public java.lang.String readLine()
UnsupportedOperationException
.readLine
in interface java.io.DataInput
null
if the end of file is
encountered before a byte can be read.public void readFully(byte[] b) throws java.io.IOException
java.io.DataInput
b
. The number of bytes
read is equal
to the length of b
.
This method blocks until one of the following conditions occurs:
b.length
bytes of input data are available, in which
case a normal return is made.
EOFException
is thrown.
IOException
other
than EOFException
is thrown.
If b
is null
,
a NullPointerException
is thrown.
If b.length
is zero, then
no bytes are read. Otherwise, the first
byte read is stored into element b[0]
,
the next one into b[1]
, and
so on.
If an exception is thrown from
this method, then it may be that some but
not all bytes of b
have been
updated with data from the input stream.
readFully
in interface java.io.DataInput
b
- the buffer into which the data is read.java.io.EOFException
- if this stream reaches the end before reading
all the bytes.java.io.IOException
- if an I/O error occurs.public void readFully(byte[] b, int off, int len) throws java.io.IOException
java.io.DataInput
len
bytes from
an input stream.
This method blocks until one of the following conditions occurs:
len
bytes
of input data are available, in which case
a normal return is made.
EOFException
is thrown.
IOException
other
than EOFException
is thrown.
If b
is null
,
a NullPointerException
is thrown.
If off
is negative, or len
is negative, or off+len
is
greater than the length of the array b
,
then an IndexOutOfBoundsException
is thrown.
If len
is zero,
then no bytes are read. Otherwise, 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
.
readFully
in interface java.io.DataInput
b
- the buffer into which the data is read.off
- an int specifying the offset into the data.len
- an int specifying the number of bytes to read.java.io.EOFException
- if this stream reaches the end before reading
all the bytes.java.io.IOException
- if an I/O error occurs.public int skipBytes(int n) throws java.io.IOException
java.io.DataInput
n
bytes
of data from the input
stream, discarding the skipped bytes. However,
it may skip
over some smaller number of
bytes, possibly zero. This may result from
any of a
number of conditions; reaching
end of file before n
bytes
have been skipped is
only one possibility.
This method never throws an EOFException
.
The actual
number of bytes skipped is returned.skipBytes
in interface java.io.DataInput
n
- the number of bytes to be skipped.java.io.IOException
- if an I/O error occurs.@CanIgnoreReturnValue public int readUnsignedByte() throws java.io.IOException
java.io.DataInput
int
, and returns
the result, which is therefore in the range
0
through 255
.
This method is suitable for reading
the byte written by the writeByte
method of interface DataOutput
if the argument to writeByte
was intended to be a value in the range
0
through 255
.readUnsignedByte
in interface java.io.DataInput
java.io.EOFException
- if this stream reaches the end before reading
all the bytes.java.io.IOException
- if an I/O error occurs.@CanIgnoreReturnValue public int readUnsignedShort() throws java.io.IOException
short
as specified by DataInputStream.readUnsignedShort()
,
except using little-endian byte order.readUnsignedShort
in interface java.io.DataInput
java.io.IOException
- if an I/O error occurs@CanIgnoreReturnValue public int readInt() throws java.io.IOException
DataInputStream.readInt()
, except using little-endian
byte order.readInt
in interface java.io.DataInput
int
in little-endian
byte orderjava.io.IOException
- if an I/O error occurs@CanIgnoreReturnValue public long readLong() throws java.io.IOException
long
as specified by DataInputStream.readLong()
, except using
little-endian byte order.readLong
in interface java.io.DataInput
long
in
little-endian byte orderjava.io.IOException
- if an I/O error occurs@CanIgnoreReturnValue public float readFloat() throws java.io.IOException
float
as specified by DataInputStream.readFloat()
, except using
little-endian byte order.readFloat
in interface java.io.DataInput
float
in
little-endian byte orderjava.io.IOException
- if an I/O error occurs@CanIgnoreReturnValue public double readDouble() throws java.io.IOException
double
as specified by DataInputStream.readDouble()
, except using
little-endian byte order.readDouble
in interface java.io.DataInput
double
in
little-endian byte orderjava.io.IOException
- if an I/O error occurs@CanIgnoreReturnValue public java.lang.String readUTF() throws java.io.IOException
java.io.DataInput
readUTF
is that it reads a representation of a Unicode
character string encoded in modified
UTF-8 format; this string of characters
is then returned as a String
.
First, two bytes are read and used to
construct an unsigned 16-bit integer in
exactly the manner of the readUnsignedShort
method . This integer value is called the
UTF length and specifies the number
of additional bytes to be read. These bytes
are then converted to characters by considering
them in groups. The length of each group
is computed from the value of the first
byte of the group. The byte following a
group, if any, is the first byte of the
next group.
If the first byte of a group
matches the bit pattern 0xxxxxxx
(where x
means "may be 0
or 1
"), then the group consists
of just that byte. The byte is zero-extended
to form a character.
If the first byte
of a group matches the bit pattern 110xxxxx
,
then the group consists of that byte a
and a second byte b
. If there
is no byte b
(because byte
a
was the last of the bytes
to be read), or if byte b
does
not match the bit pattern 10xxxxxx
,
then a UTFDataFormatException
is thrown. Otherwise, the group is converted
to the character:
(char)(((a & 0x1F) << 6) | (b & 0x3F))
If the first byte of a group
matches the bit pattern 1110xxxx
,
then the group consists of that byte a
and two more bytes b
and c
.
If there is no byte c
(because
byte a
was one of the last
two of the bytes to be read), or either
byte b
or byte c
does not match the bit pattern 10xxxxxx
,
then a UTFDataFormatException
is thrown. Otherwise, the group is converted
to the character:
(char)(((a & 0x0F) << 12) | ((b & 0x3F) << 6) | (c & 0x3F))
If the first byte of a group matches the
pattern 1111xxxx
or the pattern
10xxxxxx
, then a UTFDataFormatException
is thrown.
If end of file is encountered
at any time during this entire process,
then an EOFException
is thrown.
After every group has been converted to
a character by this process, the characters
are gathered, in the same order in which
their corresponding groups were read from
the input stream, to form a String
,
which is returned.
The writeUTF
method of interface DataOutput
may be used to write data that is suitable
for reading by this method.
readUTF
in interface java.io.DataInput
java.io.EOFException
- if this stream reaches the end
before reading all the bytes.java.io.IOException
- if an I/O error occurs.@CanIgnoreReturnValue public short readShort() throws java.io.IOException
short
as specified by DataInputStream.readShort()
, except using
little-endian byte order.readShort
in interface java.io.DataInput
short
in little-endian
byte order.java.io.IOException
- if an I/O error occurs.@CanIgnoreReturnValue public char readChar() throws java.io.IOException
DataInputStream.readChar()
, except using little-endian
byte order.readChar
in interface java.io.DataInput
char
in little-endian
byte orderjava.io.IOException
- if an I/O error occurs@CanIgnoreReturnValue public byte readByte() throws java.io.IOException
java.io.DataInput
-128
through 127
,
inclusive.
This method is suitable for
reading the byte written by the writeByte
method of interface DataOutput
.readByte
in interface java.io.DataInput
java.io.EOFException
- if this stream reaches the end before reading
all the bytes.java.io.IOException
- if an I/O error occurs.@CanIgnoreReturnValue public boolean readBoolean() throws java.io.IOException
java.io.DataInput
true
if that byte is nonzero,
false
if that byte is zero.
This method is suitable for reading
the byte written by the writeBoolean
method of interface DataOutput
.readBoolean
in interface java.io.DataInput
boolean
value read.java.io.EOFException
- if this stream reaches the end before reading
all the bytes.java.io.IOException
- if an I/O error occurs.Copyright © 2010–2021. All rights reserved.