AoCollections (AO Code Public 1.2 API)

java.lang.Object
- com.aoindustries.util.AoCollections

```
public class AoCollections
extends Object
```
General-purpose collection utilities and constants.

Author:

AO Industries, Inc.

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static class AoCollections.PeekIterator<E>
Allows peeking the first element of iteration.

Nested Classes
Modifier and Type	Class and Description
`static class`	`AoCollections.PeekIterator<E>` Allows peeking the first element of iteration.

Field Summary

Fields
Modifier and Type Field and Description

static SortedSet<?> EMPTY_SORTED_SET

Fields
Modifier and Type	Field and Description
`static SortedSet<?>`	`EMPTY_SORTED_SET`

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static <E> Iterator<E>`	`emptyIterator()` Gets the empty iterator.
`static <T> SortedSet<T>`	`emptySortedSet()` Java 1.8: use standard version
`static boolean`	`equals(Collection<?> collection1, Collection<?> collection2)` Two collections are considered equal when they are the same size and have the same elements in the same iteration order.
`static <E,R extends E> List<R>`	`filter(List<E> list, Class<R> clazz)` Filters a list for all elements of a given class.
`static int`	`hashCode(Iterable<?> iterable)` Computes the hashCode of a collection in a manner consistent with AbstractList.
`static <T> Collection<T>`	`optimalUnmodifiableCollection(Collection<T> collection)` Gets the optimal implementation for unmodifiable collection.
`static <T> List<T>`	`optimalUnmodifiableList(List<T> list)` Gets the optimal implementation for unmodifiable list.
`static <K,V> Map<K,V>`	`optimalUnmodifiableMap(Map<K,V> map)` Gets the optimal implementation for unmodifiable map.
`static <T> Set<T>`	`optimalUnmodifiableSet(Set<T> set)` Gets the optimal implementation for unmodifiable set.
`static <K,V> SortedMap<K,V>`	`optimalUnmodifiableSortedMap(SortedMap<K,V> sortedMap)` Gets the optimal implementation for unmodifiable sorted map.
`static <T> SortedSet<T>`	`optimalUnmodifiableSortedSet(SortedSet<T> sortedSet)` Gets the optimal implementation for unmodifiable sorted set.
`static <E> AoCollections.PeekIterator<E>`	`peekIterator(Iterator<? extends E> iter)` Wraps the provided iterator, allowing peek of first element.
`static <E> Iterator<E>`	`singletonIterator(E value)` Gets an unmodifiable iterator for a single object.
`static <T> SortedSet<T>`	`singletonSortedSet(T o)`
`static <T> Collection<T>`	`unmodifiableCopyCollection(Collection<T> collection)` Performs defensive shallow copy and returns unmodifiable collection.
`static <T> List<T>`	`unmodifiableCopyList(Collection<T> collection)` Performs defensive shallow copy and returns unmodifiable list.
`static <K,V> Map<K,V>`	`unmodifiableCopyMap(Map<K,V> map)` Performs defensive shallow copy and returns unmodifiable map.
`static <T> Set<T>`	`unmodifiableCopySet(Collection<T> collection)` Performs defensive shallow copy and returns unmodifiable set.
`static <K,V> SortedMap<K,V>`	`unmodifiableCopySortedMap(Map<K,V> map)` Performs defensive shallow copy and returns unmodifiable sorted map.
`static <T> SortedSet<T>`	`unmodifiableCopySortedSet(Collection<T> collection)` Performs defensive shallow copy and returns unmodifiable sorted set.
`static <E> Iterator<E>`	`unmodifiableIterator(Iterator<E> iter)` Wraps an iterator to make it unmodifiable.

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

- Field Detail
  - EMPTY_SORTED_SET
```
public static final SortedSet<?> EMPTY_SORTED_SET
```
- Method Detail
  - emptySortedSet
```
public static final <T> SortedSet<T> emptySortedSet()
```
    Java 1.8: use standard version
  - singletonSortedSet
```
public static <T> SortedSet<T> singletonSortedSet(T o)
```
  - optimalUnmodifiableCollection
```
public static <T> Collection<T> optimalUnmodifiableCollection(Collection<T> collection)
```
    Gets the optimal implementation for unmodifiable collection. If the collection is already unmodifiable, returns the same collection. If collection is empty, uses Collections.emptyList. If collection has one element, uses Collections.singletonList. Otherwise, wraps the collection with Collections.unmodifiableCollection.
  - unmodifiableCopyCollection
```
public static <T> Collection<T> unmodifiableCopyCollection(Collection<T> collection)
```
    Performs defensive shallow copy and returns unmodifiable collection.
  - optimalUnmodifiableList
```
public static <T> List<T> optimalUnmodifiableList(List<T> list)
```
    Gets the optimal implementation for unmodifiable list. If list is empty, uses Collections.emptyList. If list has one element, uses Collections.singletonList. Otherwise, wraps the list with Collections.unmodifiableList, and will also call "trimToSize" if the list is an ArrayList.
    
    See Also:
    
    Collections.emptyList(), Collections.singletonList(java.lang.Object), ArrayList.trimToSize(), Collections.unmodifiableList(java.util.List)
  - unmodifiableCopyList
```
public static <T> List<T> unmodifiableCopyList(Collection<T> collection)
```
    Performs defensive shallow copy and returns unmodifiable list.
  - optimalUnmodifiableSet
```
public static <T> Set<T> optimalUnmodifiableSet(Set<T> set)
```
    Gets the optimal implementation for unmodifiable set. If set is empty, uses Collections.emptySet. If set has one element, uses Collections.singleton. Otherwise, wraps the set with Collections.unmodifiableSet.
  - unmodifiableCopySet
```
public static <T> Set<T> unmodifiableCopySet(Collection<T> collection)
```
    Performs defensive shallow copy and returns unmodifiable set. The iteration order of the original set is maintained.
  - optimalUnmodifiableSortedSet
```
public static <T> SortedSet<T> optimalUnmodifiableSortedSet(SortedSet<T> sortedSet)
```
    Gets the optimal implementation for unmodifiable sorted set. If sorted set is empty, uses emptySortedSet. If sorted set has one element, uses singletonSortedSet. Otherwise, wraps the sorted set with Collections.unmodifiableSortedSet.
  - unmodifiableCopySortedSet
```
public static <T> SortedSet<T> unmodifiableCopySortedSet(Collection<T> collection)
```
    Performs defensive shallow copy and returns unmodifiable sorted set.
  - optimalUnmodifiableMap
```
public static <K,V> Map<K,V> optimalUnmodifiableMap(Map<K,V> map)
```
    Gets the optimal implementation for unmodifiable map. If map is empty, uses Collections.emptyMap. If map has one element, uses Collections.singletonMap. Otherwise, wraps the map with Collections.unmodifiableMap.
  - unmodifiableCopyMap
```
public static <K,V> Map<K,V> unmodifiableCopyMap(Map<K,V> map)
```
    Performs defensive shallow copy and returns unmodifiable map. The iteration order of the original set is maintained.
  - optimalUnmodifiableSortedMap
```
public static <K,V> SortedMap<K,V> optimalUnmodifiableSortedMap(SortedMap<K,V> sortedMap)
```
    Gets the optimal implementation for unmodifiable sorted map. If sorted map is empty, uses emptySortedMap. If sorted map has one element, uses singletonSortedMap. Otherwise, wraps the sorted map with Collections.unmodifiableSortedMap.
  - unmodifiableCopySortedMap
```
public static <K,V> SortedMap<K,V> unmodifiableCopySortedMap(Map<K,V> map)
```
    Performs defensive shallow copy and returns unmodifiable sorted map.
  - emptyIterator
```
public static <E> Iterator<E> emptyIterator()
```
    Gets the empty iterator.
  - singletonIterator
```
public static <E> Iterator<E> singletonIterator(E value)
```
    Gets an unmodifiable iterator for a single object.
  - unmodifiableIterator
```
public static <E> Iterator<E> unmodifiableIterator(Iterator<E> iter)
```
    Wraps an iterator to make it unmodifiable.
  - peekIterator
```
public static <E> AoCollections.PeekIterator<E> peekIterator(Iterator<? extends E> iter)
```
    Wraps the provided iterator, allowing peek of first element. Does not support null elements.
  - equals
```
public static boolean equals(Collection<?> collection1,
                             Collection<?> collection2)
```
    Two collections are considered equal when they are the same size and have the same elements in the same iteration order. If both collections are null they are also considered equal.
  - hashCode
```
public static int hashCode(Iterable<?> iterable)
```
    Computes the hashCode of a collection in a manner consistent with AbstractList.
    
    See Also:
    
    AbstractList.hashCode()
  - filter
```
public static <E,R extends E> List<R> filter(List<E> list,
                                             Class<R> clazz)
```
    Filters a list for all elements of a given class.

Class AoCollections

Nested Class Summary

Field Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

EMPTY_SORTED_SET

Method Detail

emptySortedSet

singletonSortedSet

optimalUnmodifiableCollection

unmodifiableCopyCollection

optimalUnmodifiableList

unmodifiableCopyList

optimalUnmodifiableSet

unmodifiableCopySet

optimalUnmodifiableSortedSet

unmodifiableCopySortedSet

optimalUnmodifiableMap

unmodifiableCopyMap

optimalUnmodifiableSortedMap

unmodifiableCopySortedMap

emptyIterator

singletonIterator

unmodifiableIterator

peekIterator

equals

hashCode

filter