org.infinispan.commons.api.functional

Interface EntryView.ReadEntryView<K,V>

All Superinterfaces:

MetaParam.Lookup

All Known Subinterfaces:

EntryView.ReadWriteEntryView<K,V>

Enclosing class:

EntryView

public static interface EntryView.ReadEntryView<K,V>
extends MetaParam.Lookup

Expose read-only information about a cache entry potentially associated with a key in the functional map. Typically, if the key is associated with a cache entry, that information will include value and optional MetaParam information. DESIGN RATIONALES:

• Why does ReadEntryView expose both get() and find() methods for retrieving the value? Convenience. If the caller knows for sure that the value will be present, get() offers the convenience of retrieving the value directly without having to get an Optional first.
• Why have find() return Optional? Why not get rid of it and only have get() method return null? Because nulls are evil. If a value might not be there, the user can use Optional to find out if the value might be there and deal with non-present values in a more functional way.
• Why does get() throw NoSuchElementException? Because you should only use it if you know for sure that the value will be there. If unsure, use find(). We don't want to return null to avoid people doing null checks.

Method Summary

Modifier and Type	Method and Description
Optional<V>	find() Optional value.
V	get() Returns a non-null value if the key has a value associated with it or throws NoSuchElementException if no value is associated with the.
K	key() Key of the read-only entry view.

Methods inherited from interface org.infinispan.commons.api.functional.MetaParam.Lookup

findMetaParam

Method Detail

key

K key()

Key of the read-only entry view. Guaranteed to return a non-null value.

get

V get()
throws NoSuchElementException

Returns a non-null value if the key has a value associated with it or throws NoSuchElementException if no value is associated with the.

Throws:

NoSuchElementException - if no value is associated with the key.

find

Optional<V> find()

Optional value. It'll return a non-empty value when the value is present, and empty when the value is not present.