FilterDirectoryReader.DelegatingCacheHelper (Lucene 9.11.1 core API)

java.lang.Object
- org.apache.lucene.index.FilterDirectoryReader.DelegatingCacheHelper

All Implemented Interfaces:

IndexReader.CacheHelper

Enclosing class:

FilterDirectoryReader
```
protected static class FilterDirectoryReader.DelegatingCacheHelper
extends Object
implements IndexReader.CacheHelper
```
A DelegatingCacheHelper is a CacheHelper specialization for implementing long-lived caching behaviour for FilterDirectoryReader subclasses. It uses a unique CacheKey for the purpose of implementing the onClose listener delegation for the reader.

Constructor Summary

Constructors
Modifier	Constructor	Description
`protected`	`DelegatingCacheHelper(IndexReader.CacheHelper delegate)`	Create a new DelegatingCacheHelper that delegates the cache onClose listener to another CacheHelper, but with its own unique CacheKey.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`addClosedListener(IndexReader.ClosedListener listener)`	Add a `IndexReader.ClosedListener` which will be called when the resource guarded by `IndexReader.CacheHelper.getKey()` is closed.
`IndexReader.CacheKey`	`getKey()`	Get a key that the resource can be cached on.

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

- Constructor Detail
  - DelegatingCacheHelper
```
protected DelegatingCacheHelper(IndexReader.CacheHelper delegate)
```
    Create a new DelegatingCacheHelper that delegates the cache onClose listener to another CacheHelper, but with its own unique CacheKey.
    
    Parameters:
    
    delegate - the CacheHelper to delegate the close listener to
- Method Detail
  - getKey
```
public IndexReader.CacheKey getKey()
```
    Description copied from interface: IndexReader.CacheHelper
    
    Get a key that the resource can be cached on. The given entry can be compared using identity, ie. Object.equals(java.lang.Object) is implemented as == and Object.hashCode() is implemented as System.identityHashCode(java.lang.Object).
    
    Specified by:
    
    getKey in interface IndexReader.CacheHelper
  - addClosedListener
```
public void addClosedListener(IndexReader.ClosedListener listener)
```
    Description copied from interface: IndexReader.CacheHelper
    
    Add a IndexReader.ClosedListener which will be called when the resource guarded by IndexReader.CacheHelper.getKey() is closed.
    
    Specified by:
    
    addClosedListener in interface IndexReader.CacheHelper