IndexerFunction (dxlib 3.341)

All Superinterfaces:

Serializable

All Known Subinterfaces:

IndexerFunction.IdentityKey<K,V>, IndexerFunction.IntKey<V>, IndexerFunction.LongKey<V>

All Known Implementing Classes:

IdentityIndexer, Indexer, IndexerFunction.DefaultIdentityKey, IndexerFunction.DefaultIndexerFunction, NumberKeyIndexer

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.
```
@FunctionalInterface
public interface IndexerFunction<K,V>
extends Serializable
```
A strategy that distinguishes and identifies elements in an IndexedSet and IndexedMap. The IndexerFunction defines 3 equivalent ways to identify elements:
- by value - mandatory and primary method to identify element by itself
- by object key - optional method that identifies elements using object key
- by number key - optional method that identifies elements using number key
The IndexerFunction is not restricted to use explicit key concept for identification. Identity of an element may be defined by a number of attributes, specified in a value itself, in a template object, in a formal key object, or encoded in a number key. The IndexerFunction may use all these ways interchangeable to distinguish and identify elements.
Being a strategy, the IndexerFunction is required to be stateless, concurrent and thread-safe.
The IndexerFunction is a functional interface with a sole abstract method that shall be implemented in order to use identification using explicit object key - no other methods are required to be overridden in such simple cases. There are two other functional interfaces IndexerFunction.IntKey and IndexerFunction.LongKey which are similarly designed with sole abstract methods to simplify identification using explicit number keys. There is also a functional interface IndexerFunction.IdentityKey which is similarly designed with sole abstract method for cases when explicit object keys must be compared by reference rather than using their equals method.
The IndexerFunction is Serializable, so that all concrete subclasses shall be serializable in order to support serialization of indexed set and map.

Nested Class Summary

Nested Classes
Modifier and Type	Interface and Description
`static class`	`IndexerFunction.DefaultIdentityKey` Default identity strategy that treats values as their own keys (key == value).
`static class`	`IndexerFunction.DefaultIndexerFunction` Default strategy that treats values as their own keys (key == value).
`static interface`	`IndexerFunction.IdentityKey<K,V>` A specialized `IndexerFunction` that distinguishes and identifies elements using identity comparison of object keys.
`static interface`	`IndexerFunction.IntKey<V>` An `IndexerFunction` that distinguishes and identifies elements using int keys.
`static interface`	`IndexerFunction.LongKey<V>` An `IndexerFunction` that distinguishes and identifies elements using long keys.

Field Summary

Fields
Modifier and Type	Field and Description
`static IndexerFunction`	`DEFAULT` Default strategy that treats values as their own keys (key == value) and delegates to `Object.hashCode()` and `Object.equals(Object)` methods as appropriate.
`static IndexerFunction.IdentityKey`	`DEFAULT_IDENTITY_KEY` Default strategy that treats values as their own keys (key == value) and uses object identity to compare keys (see `IndexerFunction.IdentityKey` for details).

Method Summary

All Methods Instance Methods Abstract Methods Default Methods
Modifier and Type	Method and Description
`default long`	`getNumberKey(V value)` Returns number key for specified value to be used for hashing and identification; called when explicit number key is needed or when other methods delegate operations as specified.
`K`	`getObjectKey(V value)` Returns object key for specified value to be used for hashing and identification; called when explicit object key is needed or when other methods delegate operations as specified.
`default int`	`hashCodeByKey(K key)` Returns hash code for specified object key; called when performing operations using object keys.
`default int`	`hashCodeByKey(long key)` Returns hash code for specified number key; called when performing operations using long keys.
`default int`	`hashCodeByValue(V value)` Returns hash code for specified value; called when performing value-based operations, including rehash.
`default boolean`	`matchesByKey(K key, V value)` Determines if specified object key matches specified value; called when performing operations using object keys.
`default boolean`	`matchesByKey(long key, V value)` Determines if specified number key matches specified value; called when performing operations using number keys.
`default boolean`	`matchesByValue(V newValue, V oldValue)` Determines if specified new value matches specified old value; called when performing value-based operations.

- Field Detail
  - DEFAULT
```
static final IndexerFunction DEFAULT
```
    Default strategy that treats values as their own keys (key == value) and delegates to Object.hashCode() and Object.equals(Object) methods as appropriate. This strategy does not support primitive keys.
    This strategy basically turns IndexedSet into plain hash set of objects and IndexedMap into a self-reference mapping.
  - DEFAULT_IDENTITY_KEY
```
static final IndexerFunction.IdentityKey DEFAULT_IDENTITY_KEY
```
    Default strategy that treats values as their own keys (key == value) and uses object identity to compare keys (see IndexerFunction.IdentityKey for details).
- Method Detail
  - getObjectKey
```
K getObjectKey(V value)
```
    Returns object key for specified value to be used for hashing and identification; called when explicit object key is needed or when other methods delegate operations as specified.
  - hashCodeByKey
```
default int hashCodeByKey(K key)
```
    Returns hash code for specified object key; called when performing operations using object keys.
    This implementation delegates to (key == null ? 0 : key.hashCode()) expression.
  - matchesByKey
```
default boolean matchesByKey(K key,
                             V value)
```
    Determines if specified object key matches specified value; called when performing operations using object keys.
    This implementation delegates to (key == null ? getObjectKey(value) == null : key.equals(getObjectKey(value))) expression.
  - hashCodeByValue
```
default int hashCodeByValue(V value)
```
    Returns hash code for specified value; called when performing value-based operations, including rehash.
    This implementation delegates to hashCodeByKey(getObjectKey(value)) expression.
  - matchesByValue
```
default boolean matchesByValue(V newValue,
                               V oldValue)
```
    Determines if specified new value matches specified old value; called when performing value-based operations.
    This implementation delegates to matchesByKey(getObjectKey(newValue), oldValue) expression.
  - getNumberKey
```
default long getNumberKey(V value)
```
    Returns number key for specified value to be used for hashing and identification; called when explicit number key is needed or when other methods delegate operations as specified.
    This implementation delegates to hashCodeByKey(((Number)getObjectKey(value)).longValue()) expression.
  - hashCodeByKey
```
default int hashCodeByKey(long key)
```
    Returns hash code for specified number key; called when performing operations using long keys.
    This implementation delegates to Long.hashCode(key) expression.
  - matchesByKey
```
default boolean matchesByKey(long key,
                             V value)
```
    Determines if specified number key matches specified value; called when performing operations using number keys.
    This implementation delegates to (key == getNumberKey(value)) expression.

Interface IndexerFunction<K,V>

Nested Class Summary

Field Summary

Method Summary

Field Detail

DEFAULT

DEFAULT_IDENTITY_KEY

Method Detail

getObjectKey

hashCodeByKey

matchesByKey

hashCodeByValue

matchesByValue

getNumberKey

hashCodeByKey

matchesByKey