Interface ByteArrayDataInput
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- All Superinterfaces:
DataInput
@GwtIncompatible public interface ByteArrayDataInput extends DataInput
An extension ofDataInput
for reading from in-memory byte arrays; its methods offer identical functionality but do not throwIOException
.Warning: The caller is responsible for not attempting to read past the end of the array. If any method encounters the end of the array prematurely, it throws
IllegalStateException
to signify programmer error. This behavior is a technical violation of the supertype's contract, which specifies a checked exception.- Since:
- 1.0
- Author:
- Kevin Bourrillion
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Method Summary
All Methods Instance Methods Abstract 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 two input bytes and returns achar
value.double
readDouble()
Reads eight input bytes and returns adouble
value.float
readFloat()
Reads four input bytes and returns afloat
value.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 four input bytes and returns anint
value.String
readLine()
Reads the next line of text from the input stream.long
readLong()
Reads eight input bytes and returns along
value.short
readShort()
Reads two input bytes and returns ashort
value.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 two input bytes and returns anint
value in the range0
through65535
.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.
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Method Detail
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readFully
void readFully(byte[] b)
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.
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readFully
void readFully(byte[] b, int off, int len)
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
.
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skipBytes
int skipBytes(int n)
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.
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readBoolean
@CanIgnoreReturnValue boolean readBoolean()
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.
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readByte
@CanIgnoreReturnValue byte readByte()
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
.
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readUnsignedByte
@CanIgnoreReturnValue int readUnsignedByte()
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.
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readShort
@CanIgnoreReturnValue short readShort()
Description copied from interface:java.io.DataInput
Reads two input bytes and returns ashort
value. Leta
be the first byte read andb
be the second byte. The value returned is:
This method is suitable for reading the bytes written by the(short)((a << 8) | (b & 0xff))
writeShort
method of interfaceDataOutput
.
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readUnsignedShort
@CanIgnoreReturnValue int readUnsignedShort()
Description copied from interface:java.io.DataInput
Reads two input bytes and returns anint
value in the range0
through65535
. Leta
be the first byte read andb
be the second byte. The value returned is:
This method is suitable for reading the bytes written by the(((a & 0xff) << 8) | (b & 0xff))
writeShort
method of interfaceDataOutput
if the argument towriteShort
was intended to be a value in the range0
through65535
.- Specified by:
readUnsignedShort
in interfaceDataInput
- Returns:
- the unsigned 16-bit value read.
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readChar
@CanIgnoreReturnValue char readChar()
Description copied from interface:java.io.DataInput
Reads two input bytes and returns achar
value. Leta
be the first byte read andb
be the second byte. The value returned is:
This method is suitable for reading bytes written by the(char)((a << 8) | (b & 0xff))
writeChar
method of interfaceDataOutput
.
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readInt
@CanIgnoreReturnValue int readInt()
Description copied from interface:java.io.DataInput
Reads four input bytes and returns anint
value. Leta-d
be the first through fourth bytes read. The value returned is:
This method is suitable for reading bytes written by the(((a & 0xff) << 24) | ((b & 0xff) << 16) | ((c & 0xff) << 8) | (d & 0xff))
writeInt
method of interfaceDataOutput
.
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readLong
@CanIgnoreReturnValue long readLong()
Description copied from interface:java.io.DataInput
Reads eight input bytes and returns along
value. Leta-h
be the first through eighth bytes read. The value returned is:(((long)(a & 0xff) << 56) | ((long)(b & 0xff) << 48) | ((long)(c & 0xff) << 40) | ((long)(d & 0xff) << 32) | ((long)(e & 0xff) << 24) | ((long)(f & 0xff) << 16) | ((long)(g & 0xff) << 8) | ((long)(h & 0xff)))
This method is suitable for reading bytes written by the
writeLong
method of interfaceDataOutput
.
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readFloat
@CanIgnoreReturnValue float readFloat()
Description copied from interface:java.io.DataInput
Reads four input bytes and returns afloat
value. It does this by first constructing anint
value in exactly the manner of thereadInt
method, then converting thisint
value to afloat
in exactly the manner of the methodFloat.intBitsToFloat
. This method is suitable for reading bytes written by thewriteFloat
method of interfaceDataOutput
.
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readDouble
@CanIgnoreReturnValue double readDouble()
Description copied from interface:java.io.DataInput
Reads eight input bytes and returns adouble
value. It does this by first constructing along
value in exactly the manner of thereadLong
method, then converting thislong
value to adouble
in exactly the manner of the methodDouble.longBitsToDouble
. This method is suitable for reading bytes written by thewriteDouble
method of interfaceDataOutput
.- Specified by:
readDouble
in interfaceDataInput
- Returns:
- the
double
value read.
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readLine
@CanIgnoreReturnValue @CheckForNull String readLine()
Description copied from interface:java.io.DataInput
Reads the next line of text from the input stream. It reads successive bytes, converting each byte separately into a character, until it encounters a line terminator or end of file; the characters read are then returned as aString
. Note that because this method processes bytes, it does not support input of the full Unicode character set.If end of file is encountered before even one byte can be read, then
null
is returned. Otherwise, each byte that is read is converted to typechar
by zero-extension. If the character'\n'
is encountered, it is discarded and reading ceases. If the character'\r'
is encountered, it is discarded and, if the following byte converts to the character'\n'
, then that is discarded also; reading then ceases. If end of file is encountered before either of the characters'\n'
and'\r'
is encountered, reading ceases. Once reading has ceased, aString
is returned that contains all the characters read and not discarded, taken in order. Note that every character in this string will have a value less than\u0100
, that is,(char)256
.
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readUTF
@CanIgnoreReturnValue String readUTF()
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.
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