java.lang.Object
- org.apache.lucene.codecs.PostingsFormat

All Implemented Interfaces:

NamedSPILoader.NamedSPI

Direct Known Subclasses:

BlockTreeOrdsPostingsFormat, BloomFilteringPostingsFormat, CompletionPostingsFormat, DirectPostingsFormat, FSTPostingsFormat, IDVersionPostingsFormat, Lucene50PostingsFormat, Lucene84PostingsFormat, PerFieldPostingsFormat, SimpleTextPostingsFormat, UniformSplitPostingsFormat
```
public abstract class PostingsFormat
extends java.lang.Object
implements NamedSPILoader.NamedSPI
```
Encodes/decodes terms, postings, and proximity data.
Note, when extending this class, the name (getName()) may written into the index in certain configurations. In order for the segment to be read, the name must resolve to your implementation via forName(String). This method uses Java's Service Provider Interface (SPI) to resolve format names.
If you implement your own format, make sure that it has a no-arg constructor so SPI can load it.

See Also:

ServiceLoader

Nested Class Summary

Nested Classes
Modifier and Type	Class	Description
`private static class`	`PostingsFormat.Holder`	This static holder class prevents classloading deadlock by delaying init of postings formats until needed.

Field Summary

Fields
Modifier and Type	Field	Description
`static PostingsFormat[]`	`EMPTY`	Zero-length `PostingsFormat` array.
`private java.lang.String`	`name`	Unique name that's used to retrieve this format when reading the index.

Constructor Summary

Constructors
Modifier Constructor Description

protected PostingsFormat(java.lang.String name)
Creates a new postings format.

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method	Description
`static java.util.Set<java.lang.String>`	`availablePostingsFormats()`	returns a list of all available format names
`abstract FieldsConsumer`	`fieldsConsumer(SegmentWriteState state)`	Writes a new segment
`abstract FieldsProducer`	`fieldsProducer(SegmentReadState state)`	Reads a segment.
`static PostingsFormat`	`forName(java.lang.String name)`	looks up a format by name
`java.lang.String`	`getName()`	Returns this posting format's name
`static void`	`reloadPostingsFormats(java.lang.ClassLoader classloader)`	Reloads the postings format list from the given `ClassLoader`.
`java.lang.String`	`toString()`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - EMPTY
```
public static final PostingsFormat[] EMPTY
```
    Zero-length PostingsFormat array.
  - name
```
private final java.lang.String name
```
    Unique name that's used to retrieve this format when reading the index.
- Constructor Detail
  - PostingsFormat
```
protected PostingsFormat(java.lang.String name)
```
    Creates a new postings format.
    The provided name will be written into the index segment in some configurations (such as when using PerFieldPostingsFormat): in such configurations, for the segment to be read this class should be registered with Java's SPI mechanism (registered in META-INF/ of your jar file, etc).
    
    Parameters:
    
    name - must be all ascii alphanumeric, and less than 128 characters in length.
- Method Detail
  - getName
```
public final java.lang.String getName()
```
    Returns this posting format's name
    
    Specified by:
    
    getName in interface NamedSPILoader.NamedSPI
  - fieldsConsumer
```
public abstract FieldsConsumer fieldsConsumer(SegmentWriteState state)
                                       throws java.io.IOException
```
    Writes a new segment
    
    Throws:
    
    java.io.IOException
  - fieldsProducer
```
public abstract FieldsProducer fieldsProducer(SegmentReadState state)
                                       throws java.io.IOException
```
    Reads a segment. NOTE: by the time this call returns, it must hold open any files it will need to use; else, those files may be deleted. Additionally, required files may be deleted during the execution of this call before there is a chance to open them. Under these circumstances an IOException should be thrown by the implementation. IOExceptions are expected and will automatically cause a retry of the segment opening logic with the newly revised segments.
    
    Throws:
    
    java.io.IOException
  - toString
```
public java.lang.String toString()
```
    Overrides:
    
    toString in class java.lang.Object
  - forName
```
public static PostingsFormat forName(java.lang.String name)
```
    looks up a format by name
  - availablePostingsFormats
```
public static java.util.Set<java.lang.String> availablePostingsFormats()
```
    returns a list of all available format names
  - reloadPostingsFormats
```
public static void reloadPostingsFormats(java.lang.ClassLoader classloader)
```
    Reloads the postings format list from the given ClassLoader. Changes to the postings formats are visible after the method ends, all iterators (availablePostingsFormats(),...) stay consistent.
    NOTE: Only new postings formats are added, existing ones are never removed or replaced.
    This method is expensive and should only be called for discovery of new postings formats on the given classpath/classloader!

Class PostingsFormat

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

EMPTY

name

Constructor Detail

PostingsFormat

Method Detail

getName

fieldsConsumer

fieldsProducer

toString

forName

availablePostingsFormats

reloadPostingsFormats