Class LittleEndianDataInputStream
- java.lang.Object
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- java.io.InputStream
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- java.io.FilterInputStream
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- com.google.common.io.LittleEndianDataInputStream
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- All Implemented Interfaces:
Closeable
,DataInput
,AutoCloseable
@Beta @GwtIncompatible public final class LittleEndianDataInputStream extends FilterInputStream implements DataInput
An implementation ofDataInput
that uses little-endian byte ordering for readingshort
,int
,float
,double
, andlong
values.Note: This class intentionally violates the specification of its supertype
DataInput
, which explicitly requires big-endian byte order.- Since:
- 8.0
- Author:
- Chris Nokleberg, Keith Bottner
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Field Summary
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Fields inherited from class java.io.FilterInputStream
in
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Constructor Summary
Constructors Constructor Description LittleEndianDataInputStream(InputStream in)
Creates aLittleEndianDataInputStream
that wraps the given stream.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description boolean
readBoolean()
Reads one input byte and returnstrue
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 byDataInputStream.readChar()
, except using little-endian byte order.double
readDouble()
Reads adouble
as specified byDataInputStream.readDouble()
, except using little-endian byte order.float
readFloat()
Reads afloat
as specified byDataInputStream.readFloat()
, except using little-endian byte order.void
readFully(byte[] b)
Reads some bytes from an input stream and stores them into the buffer arrayb
.void
readFully(byte[] b, int off, int len)
Readslen
bytes from an input stream.int
readInt()
Reads an integer as specified byDataInputStream.readInt()
, except using little-endian byte order.String
readLine()
This method will throw anUnsupportedOperationException
.long
readLong()
Reads along
as specified byDataInputStream.readLong()
, except using little-endian byte order.short
readShort()
Reads ashort
as specified byDataInputStream.readShort()
, except using little-endian byte order.int
readUnsignedByte()
Reads one input byte, zero-extends it to typeint
, and returns the result, which is therefore in the range0
through255
.int
readUnsignedShort()
Reads an unsignedshort
as specified byDataInputStream.readUnsignedShort()
, except using little-endian byte order.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 overn
bytes of data from the input stream, discarding the skipped bytes.-
Methods inherited from class java.io.FilterInputStream
available, close, mark, markSupported, read, read, read, reset, skip
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Methods inherited from class java.io.InputStream
nullInputStream, readAllBytes, readNBytes, readNBytes, transferTo
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Constructor Detail
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LittleEndianDataInputStream
public LittleEndianDataInputStream(InputStream in)
Creates aLittleEndianDataInputStream
that wraps the given stream.- Parameters:
in
- the stream to delegate to
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Method Detail
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readLine
@CanIgnoreReturnValue public String readLine()
This method will throw anUnsupportedOperationException
.
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readFully
public void readFully(byte[] b) throws IOException
Description copied from interface:java.io.DataInput
Reads some bytes from an input stream and stores them into the buffer arrayb
. The number of bytes read is equal to the length ofb
.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.- End of
file is detected, in which case an
EOFException
is thrown. - An I/O error occurs, in
which case an
IOException
other thanEOFException
is thrown.
If
b
isnull
, aNullPointerException
is thrown. Ifb.length
is zero, then no bytes are read. Otherwise, the first byte read is stored into elementb[0]
, the next one intob[1]
, and so on. If an exception is thrown from this method, then it may be that some but not all bytes ofb
have been updated with data from the input stream.- Specified by:
readFully
in interfaceDataInput
- Parameters:
b
- the buffer into which the data is read.- Throws:
EOFException
- if this stream reaches the end before reading all the bytes.IOException
- if an I/O error occurs.
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readFully
public void readFully(byte[] b, int off, int len) throws IOException
Description copied from interface:java.io.DataInput
Readslen
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.- End of file
is detected, in which case an
EOFException
is thrown. - An I/O error occurs, in
which case an
IOException
other thanEOFException
is thrown.
If
b
isnull
, aNullPointerException
is thrown. Ifoff
is negative, orlen
is negative, oroff+len
is greater than the length of the arrayb
, then anIndexOutOfBoundsException
is thrown. Iflen
is zero, then no bytes are read. Otherwise, the first byte read is stored into elementb[off]
, the next one intob[off+1]
, and so on. The number of bytes read is, at most, equal tolen
.- Specified by:
readFully
in interfaceDataInput
- Parameters:
b
- the buffer into which the data is read.off
- an int specifying the offset in the data arrayb
.len
- an int specifying the number of bytes to read.- Throws:
EOFException
- if this stream reaches the end before reading all the bytes.IOException
- if an I/O error occurs.
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skipBytes
public int skipBytes(int n) throws IOException
Description copied from interface:java.io.DataInput
Makes an attempt to skip overn
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 beforen
bytes have been skipped is only one possibility. This method never throws anEOFException
. The actual number of bytes skipped is returned.- Specified by:
skipBytes
in interfaceDataInput
- Parameters:
n
- the number of bytes to be skipped.- Returns:
- the number of bytes actually skipped.
- Throws:
IOException
- if an I/O error occurs.
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readUnsignedByte
@CanIgnoreReturnValue public int readUnsignedByte() throws IOException
Description copied from interface:java.io.DataInput
Reads one input byte, zero-extends it to typeint
, and returns the result, which is therefore in the range0
through255
. This method is suitable for reading the byte written by thewriteByte
method of interfaceDataOutput
if the argument towriteByte
was intended to be a value in the range0
through255
.- Specified by:
readUnsignedByte
in interfaceDataInput
- Returns:
- the unsigned 8-bit value read.
- Throws:
EOFException
- if this stream reaches the end before reading all the bytes.IOException
- if an I/O error occurs.
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readUnsignedShort
@CanIgnoreReturnValue public int readUnsignedShort() throws IOException
Reads an unsignedshort
as specified byDataInputStream.readUnsignedShort()
, except using little-endian byte order.- Specified by:
readUnsignedShort
in interfaceDataInput
- Returns:
- the next two bytes of the input stream, interpreted as an unsigned 16-bit integer in little-endian byte order
- Throws:
IOException
- if an I/O error occurs
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readInt
@CanIgnoreReturnValue public int readInt() throws IOException
Reads an integer as specified byDataInputStream.readInt()
, except using little-endian byte order.- Specified by:
readInt
in interfaceDataInput
- Returns:
- the next four bytes of the input stream, interpreted as an
int
in little-endian byte order - Throws:
IOException
- if an I/O error occurs
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readLong
@CanIgnoreReturnValue public long readLong() throws IOException
Reads along
as specified byDataInputStream.readLong()
, except using little-endian byte order.- Specified by:
readLong
in interfaceDataInput
- Returns:
- the next eight bytes of the input stream, interpreted as a
long
in little-endian byte order - Throws:
IOException
- if an I/O error occurs
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readFloat
@CanIgnoreReturnValue public float readFloat() throws IOException
Reads afloat
as specified byDataInputStream.readFloat()
, except using little-endian byte order.- Specified by:
readFloat
in interfaceDataInput
- Returns:
- the next four bytes of the input stream, interpreted as a
float
in little-endian byte order - Throws:
IOException
- if an I/O error occurs
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readDouble
@CanIgnoreReturnValue public double readDouble() throws IOException
Reads adouble
as specified byDataInputStream.readDouble()
, except using little-endian byte order.- Specified by:
readDouble
in interfaceDataInput
- Returns:
- the next eight bytes of the input stream, interpreted as a
double
in little-endian byte order - Throws:
IOException
- if an I/O error occurs
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readUTF
@CanIgnoreReturnValue public String readUTF() throws IOException
Description copied from interface:java.io.DataInput
Reads in a string that has been encoded using a modified UTF-8 format. The general contract ofreadUTF
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 aString
.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
(wherex
means "may be0
or1
"), 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 bytea
and a second byteb
. If there is no byteb
(because bytea
was the last of the bytes to be read), or if byteb
does not match the bit pattern10xxxxxx
, then aUTFDataFormatException
is thrown. Otherwise, the group is converted to the character:
If the first byte of a group matches the bit pattern(char)(((a & 0x1F) << 6) | (b & 0x3F))
1110xxxx
, then the group consists of that bytea
and two more bytesb
andc
. If there is no bytec
(because bytea
was one of the last two of the bytes to be read), or either byteb
or bytec
does not match the bit pattern10xxxxxx
, then aUTFDataFormatException
is thrown. Otherwise, the group is converted to the character:
If the first byte of a group matches the pattern(char)(((a & 0x0F) << 12) | ((b & 0x3F) << 6) | (c & 0x3F))
1111xxxx
or the pattern10xxxxxx
, then aUTFDataFormatException
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 interfaceDataOutput
may be used to write data that is suitable for reading by this method.- Specified by:
readUTF
in interfaceDataInput
- Returns:
- a Unicode string.
- Throws:
EOFException
- if this stream reaches the end before reading all the bytes.IOException
- if an I/O error occurs.UTFDataFormatException
- if the bytes do not represent a valid modified UTF-8 encoding of a string.
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readShort
@CanIgnoreReturnValue public short readShort() throws IOException
Reads ashort
as specified byDataInputStream.readShort()
, except using little-endian byte order.- Specified by:
readShort
in interfaceDataInput
- Returns:
- the next two bytes of the input stream, interpreted as a
short
in little-endian byte order. - Throws:
IOException
- if an I/O error occurs.
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readChar
@CanIgnoreReturnValue public char readChar() throws IOException
Reads a char as specified byDataInputStream.readChar()
, except using little-endian byte order.- Specified by:
readChar
in interfaceDataInput
- Returns:
- the next two bytes of the input stream, interpreted as a
char
in little-endian byte order - Throws:
IOException
- if an I/O error occurs
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readByte
@CanIgnoreReturnValue public byte readByte() throws IOException
Description copied from interface:java.io.DataInput
Reads and returns one input byte. The byte is treated as a signed value in the range-128
through127
, inclusive. This method is suitable for reading the byte written by thewriteByte
method of interfaceDataOutput
.- Specified by:
readByte
in interfaceDataInput
- Returns:
- the 8-bit value read.
- Throws:
EOFException
- if this stream reaches the end before reading all the bytes.IOException
- if an I/O error occurs.
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readBoolean
@CanIgnoreReturnValue public boolean readBoolean() throws IOException
Description copied from interface:java.io.DataInput
Reads one input byte and returnstrue
if that byte is nonzero,false
if that byte is zero. This method is suitable for reading the byte written by thewriteBoolean
method of interfaceDataOutput
.- Specified by:
readBoolean
in interfaceDataInput
- Returns:
- the
boolean
value read. - Throws:
EOFException
- if this stream reaches the end before reading all the bytes.IOException
- if an I/O error occurs.
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