public abstract class DataInput extends Object implements Cloneable
DataInput
may only be used from one thread, because it is not
thread safe (it keeps internal state like file position). To allow
multithreaded use, every DataInput
instance must be cloned before
used in another thread. Subclasses must therefore implement clone()
,
returning a new DataInput
which operates on the same underlying
resource, but positioned independently.
Constructor and Description |
---|
DataInput() |
Modifier and Type | Method and Description |
---|---|
DataInput |
clone()
Returns a clone of this stream.
|
abstract byte |
readByte()
Reads and returns a single byte.
|
abstract void |
readBytes(byte[] b,
int offset,
int len)
Reads a specified number of bytes into an array at the specified offset.
|
void |
readBytes(byte[] b,
int offset,
int len,
boolean useBuffer)
Reads a specified number of bytes into an array at the
specified offset with control over whether the read
should be buffered (callers who have their own buffer
should pass in "false" for useBuffer).
|
int |
readInt()
Reads four bytes and returns an int.
|
long |
readLong()
Reads eight bytes and returns a long.
|
Map<String,String> |
readMapOfStrings()
Reads a Map<String,String> previously written
with
DataOutput.writeMapOfStrings(Map) . |
Set<String> |
readSetOfStrings()
Reads a Set<String> previously written
with
DataOutput.writeSetOfStrings(Set) . |
short |
readShort()
Reads two bytes and returns a short.
|
String |
readString()
Reads a string.
|
int |
readVInt()
Reads an int stored in variable-length format.
|
long |
readVLong()
Reads a long stored in variable-length format.
|
int |
readZInt()
Read a
zig-zag -encoded
variable-length integer. |
long |
readZLong()
Read a
zig-zag -encoded
variable-length integer. |
void |
skipBytes(long numBytes)
Skip over
numBytes bytes. |
public abstract byte readByte() throws IOException
IOException
DataOutput.writeByte(byte)
public abstract void readBytes(byte[] b, int offset, int len) throws IOException
b
- the array to read bytes intooffset
- the offset in the array to start storing byteslen
- the number of bytes to readIOException
DataOutput.writeBytes(byte[],int)
public void readBytes(byte[] b, int offset, int len, boolean useBuffer) throws IOException
BufferedIndexInput
respects this parameter.b
- the array to read bytes intooffset
- the offset in the array to start storing byteslen
- the number of bytes to readuseBuffer
- set to false if the caller will handle
buffering.IOException
DataOutput.writeBytes(byte[],int)
public short readShort() throws IOException
IOException
DataOutput.writeByte(byte)
public int readInt() throws IOException
IOException
DataOutput.writeInt(int)
public int readVInt() throws IOException
The format is described further in DataOutput.writeVInt(int)
.
IOException
DataOutput.writeVInt(int)
public int readZInt() throws IOException
zig-zag
-encoded
variable-length
integer.IOException
DataOutput.writeZInt(int)
public long readLong() throws IOException
IOException
DataOutput.writeLong(long)
public long readVLong() throws IOException
The format is described further in DataOutput.writeVInt(int)
.
IOException
DataOutput.writeVLong(long)
public long readZLong() throws IOException
zig-zag
-encoded
variable-length
integer. Reads between one and ten
bytes.IOException
DataOutput.writeZLong(long)
public String readString() throws IOException
IOException
DataOutput.writeString(String)
public DataInput clone()
Clones of a stream access the same data, and are positioned at the same point as the stream they were cloned from.
Expert: Subclasses must ensure that clones may be positioned at different points in the input from each other and from the stream they were cloned from.
public Map<String,String> readMapOfStrings() throws IOException
DataOutput.writeMapOfStrings(Map)
.IOException
public Set<String> readSetOfStrings() throws IOException
DataOutput.writeSetOfStrings(Set)
.IOException
public void skipBytes(long numBytes) throws IOException
numBytes
bytes. The contract on this method is that it
should have the same behavior as reading the same number of bytes into a
buffer and discarding its content. Negative values of numBytes
are not supported.IOException
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