Class DataOutput

Abstract base class for performing write operations of Lucene's low-level data types.

DataOutput may only be used from one thread, because it is not thread safe (it keeps internal state like file position).

Inheritance
System.Object
DataOutput
ByteArrayDataOutput
IndexOutput
OutputStreamDataOutput
GrowableByteArrayDataOutput
PagedBytes.PagedBytesDataOutput
Inherited Members
System.Object.Equals(System.Object)
System.Object.Equals(System.Object, System.Object)
System.Object.GetHashCode()
System.Object.GetType()
System.Object.MemberwiseClone()
System.Object.ReferenceEquals(System.Object, System.Object)
System.Object.ToString()
Namespace: Lucene.Net.Store
Assembly: Lucene.Net.dll
Syntax
public abstract class DataOutput

Methods

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CopyBytes(DataInput, Int64)

Copy numBytes bytes from input to ourself.

Declaration
public virtual void CopyBytes(DataInput input, long numBytes)
Parameters
Type Name Description
DataInput input
System.Int64 numBytes
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WriteByte(Byte)

Writes a single byte.

The most primitive data type is an eight-bit byte. Files are accessed as sequences of bytes. All other data types are defined as sequences of bytes, so file formats are byte-order independent.

Declaration
public abstract void WriteByte(byte b)
Parameters
Type Name Description
System.Byte b
See Also
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WriteBytes(Byte[], Int32)

Writes an array of bytes.

Declaration
public virtual void WriteBytes(byte[] b, int length)
Parameters
Type Name Description
System.Byte[] b

the bytes to write
System.Int32 length

the number of bytes to write
See Also
ReadBytes(System.Byte[], System.Int32, System.Int32)
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WriteBytes(Byte[], Int32, Int32)

Writes an array of bytes.

Declaration
public abstract void WriteBytes(byte[] b, int offset, int length)
Parameters
Type Name Description
System.Byte[] b

the bytes to write

System.Int32 offset

the offset in the byte array

System.Int32 length

the number of bytes to write

See Also
ReadBytes(System.Byte[], System.Int32, System.Int32)
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WriteInt16(Int16)

Writes a short as two bytes.

NOTE: this was writeShort() in Lucene

Declaration
public virtual void WriteInt16(short i)
Parameters
Type Name Description
System.Int16 i
See Also
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WriteInt32(Int32)

Writes an System.Int32 as four bytes.

32-bit unsigned integer written as four bytes, high-order bytes first.

NOTE: this was writeInt() in Lucene

Declaration
public virtual void WriteInt32(int i)
Parameters
Type Name Description
System.Int32 i
See Also
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WriteInt64(Int64)

Writes a System.Int64 as eight bytes.

64-bit unsigned integer written as eight bytes, high-order bytes first.

NOTE: this was writeLong() in Lucene

Declaration
public virtual void WriteInt64(long i)
Parameters
Type Name Description
System.Int64 i
See Also
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WriteString(String)

Writes a string.

Writes strings as UTF-8 encoded bytes. First the length, in bytes, is written as a WriteVInt32(Int32), followed by the bytes.

Declaration
public virtual void WriteString(string s)
Parameters
Type Name Description
System.String s
See Also
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WriteStringSet(ISet<String>)

Writes a System.String set.

First the size is written as an WriteInt32(Int32), followed by each value written as a WriteString(String).

Declaration
public virtual void WriteStringSet(ISet<string> set)
Parameters
Type Name Description
System.Collections.Generic.ISet<System.String> set

Input ISet{string}. May be null (equivalent to an empty set)

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WriteStringStringMap(IDictionary<String, String>)

Writes a .

First the size is written as an WriteInt32(Int32), followed by each key-value pair written as two consecutive WriteString(String)s.

Declaration
public virtual void WriteStringStringMap(IDictionary<string, string> map)
Parameters
Type Name Description
System.Collections.Generic.IDictionary<System.String, System.String> map

Input . May be null (equivalent to an empty dictionary)

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WriteVInt32(Int32)

Writes an System.Int32 in a variable-length format. Writes between one and five bytes. Smaller values take fewer bytes. Negative numbers are supported, but should be avoided.

VByte is a variable-length format for positive integers is defined where the high-order bit of each byte indicates whether more bytes remain to be read. The low-order seven bits are appended as increasingly more significant bits in the resulting integer value. Thus values from zero to 127 may be stored in a single byte, values from 128 to 16,383 may be stored in two bytes, and so on.

VByte Encoding Example

ValueByte 1Byte 2Byte 3
000000000
100000001
200000010
...
12701111111
1281000000000000001
1291000000100000001
1301000001000000001
...
16,3831111111101111111
16,384100000001000000000000001
16,385100000011000000000000001
...

this provides compression while still being efficient to decode.

NOTE: this was writeVInt() in Lucene

Declaration
public void WriteVInt32(int i)
Parameters
Type Name Description
System.Int32 i

Smaller values take fewer bytes. Negative numbers are supported, but should be avoided.

Exceptions
Type Condition
System.IO.IOException

If there is an I/O error writing to the underlying medium.

See Also
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WriteVInt64(Int64)

Writes an System.Int64 in a variable-length format. Writes between one and nine bytes. Smaller values take fewer bytes. Negative numbers are not supported.

The format is described further in WriteVInt32(Int32).

NOTE: this was writeVLong() in Lucene

Declaration
public void WriteVInt64(long i)
Parameters
Type Name Description
System.Int64 i
See Also