CollectionUtils (Apache Juneau 8.1.3)

java.lang.Object
- org.apache.juneau.internal.CollectionUtils

public final class CollectionUtils
extends Object

Utility methods for collections.

Constructor Summary

Constructors
Constructor and Description

CollectionUtils()

Constructors
Constructor and Description
`CollectionUtils()`

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static <T> List<T>`	`addIfNotNull(List<T> l, T o)` Add a value to a list if the value is not null.
`static List<?>`	`addReverse(List list, List append)` Adds the contents of one list to the other in reverse order.
`static List<?>`	`addReverse(List list, Object[] append)` Adds the contents of the array to the list in reverse order.
`static <T> List<T>`	`addToList(List<T> l, Collection<T> val)` Copies the specified values into an existing list.
`static <T> List<T>`	`addToList(List<T> appendTo, Object[] values, Class<T> type, Type... args)` Adds a set of values to an existing list.
`static <K,V> Map<K,V>`	`addToMap(Map<K,V> m, K key, V value)` Adds a single entry into an existing map.
`static <K,V> Map<K,V>`	`addToMap(Map<K,V> m, Map<K,V> val)` Copies the specified values into an existing map.
`static <K,V> Map<K,V>`	`addToMap(Map<K,V> appendTo, Object[] values, Class<K> keyType, Class<V> valueType, Type... valueTypeArgs)` Adds a set of values to an existing map.
`static <K,V> Map<K,V>`	`addToSortedMap(Map<K,V> m, K key, V value, Comparator<K> comparator)` Adds a single entry into an existing map.
`static <K,V> Map<K,V>`	`addToSortedMap(Map<K,V> m, Map<K,V> val, Comparator<K> comparator)` Copies the specified values into an existing map.
`static <T> List<T>`	`emptyList()` Simple passthrough to `Collections.emptyList()`
`static <K,V> Map<K,V>`	`emptyMap()` Simple passthrough to `Collections.emptyMap()`
`static <T> Set<T>`	`emptySet()` Simple passthrough to `Collections.emptySet()`
`static <T> List<T>`	`immutableList(Collection<T> l)` Creates an immutable list from the specified collection.
`static <T> List<T>`	`immutableList(T[] l)` Creates an immutable list from the specified array.
`static <K,V> Map<K,V>`	`immutableMap(Map<K,V> m)` Creates an immutable map from the specified map.
`static <T> Iterable<T>`	`iterable(Collection<T> c, boolean reverse)` Returns an iterable over the specified collection.
`static <E> Iterable<E>`	`iterable(Enumeration<E> e)` Returns an iterable over the specified enumeration.
`static <T> Iterable<T>`	`iterable(List<T> c, boolean reverse)` Returns an iterable over the specified list.
`static <T> Iterable<T>`	`iterable(T[] c, boolean reverse)` Returns an iterable over the specified array.
`static <T> Set<T>`	`newHashSet(T... values)` Converts the specified arguments into a modifiable `HashSet`.
`static <T> Set<T>`	`newLinkedHashSet(T... values)` Converts the specified arguments into a modifiable `LinkedHashSet`.
`static <T> List<T>`	`newList(Collection<T> val)` Creates a new list from the specified collection.
`static <K,V> Map<K,V>`	`newMap(Map<K,V> val)` Creates a new map from the specified map.
`static Set<String>`	`newSortedCaseInsensitiveSet(String... values)` Creates a case-insensitive ordered set out of the specified string values.
`static Set<String>`	`newSortedCaseInsensitiveSet(String values)` Creates a case-insensitive ordered set out of the specified string values.
`static <K,V> Map<K,V>`	`newSortedMap(Map<K,V> val, Comparator<K> comparator)` Creates a new map from the specified map.
`static <T> Set<T>`	`newUnmodifiableHashSet(T... values)` Converts the specified arguments into an unmodifiable `HashSet`.
`static <T> Set<T>`	`newUnmodifiableLinkedHashSet(T... values)` Converts the specified arguments into an unmodifiable `LinkedHashSet`.
`static Set<String>`	`newUnmodifiableSortedCaseInsensitiveSet(String values)` Same as `newSortedCaseInsensitiveSet(String)` but makes the set unmodifiable.
`static <T> Iterable<T>`	`reverseIterable(List<T> c)` Returns a reverse iterable over the specified list.
`static <T> Iterable<T>`	`reverseIterable(T[] c)` Returns a reverse iterable over the specified array.
`static <T> List<T>`	`unmodifiableList(List<T> l)` Creates an unmodifiable list from the specified list.
`static <T> List<T>`	`unmodifiableList(T[] l)` Creates an unmodifiable list from the specified array.
`static <K,V> Map<K,V>`	`unmodifiableMap(Map<K,V> m)` Creates an unmodifiable map from the specified map.

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

- Constructor Detail
  - CollectionUtils
```
public CollectionUtils()
```
- Method Detail
  - addIfNotNull
```
public static <T> List<T> addIfNotNull(List<T> l,
                                       T o)
```
    Add a value to a list if the value is not null.
    
    Parameters:
    
    l - The list to add to.
    
    o - The element to add.
    
    Returns:
    
    The same list.
  - addReverse
```
public static List<?> addReverse(List list,
                                 List append)
```
    Adds the contents of one list to the other in reverse order.
    i.e. add values from 2nd list from end-to-start order to the end of the 1st list.
    
    Parameters:
    
    list - The list to append to.
    
    append - Contains the values to append to the list.
    
    Returns:
    
    The same list.
  - addReverse
```
public static List<?> addReverse(List list,
                                 Object[] append)
```
    Adds the contents of the array to the list in reverse order.
    i.e. add values from the array from end-to-start order to the end of the list.
    
    Parameters:
    
    list - The list to append to.
    
    append - Contains the values to append to the list.
    
    Returns:
    
    The same list.
  - iterable
```
public static <T> Iterable<T> iterable(Collection<T> c,
                                       boolean reverse)
```
    Returns an iterable over the specified collection.
    
    Parameters:
    
    c - The collection to iterate over.
    
    reverse - If true, iterate in reverse order.
    
    Returns:
    
    An iterable over the collection.
  - iterable
```
public static <T> Iterable<T> iterable(List<T> c,
                                       boolean reverse)
```
    Returns an iterable over the specified list.
    
    Parameters:
    
    c - The collection to iterate over.
    
    reverse - If true, iterate in reverse order.
    
    Returns:
    
    An iterable over the collection.
  - reverseIterable
```
public static <T> Iterable<T> reverseIterable(List<T> c)
```
    Returns a reverse iterable over the specified list.
    
    Parameters:
    
    c - The collection to iterate over.
    
    Returns:
    
    An iterable over the collection.
  - iterable
```
public static <T> Iterable<T> iterable(T[] c,
                                       boolean reverse)
```
    Returns an iterable over the specified array.
    
    Parameters:
    
    c - The collection to iterate over.
    
    reverse - If true, iterate in reverse order.
    
    Returns:
    
    An iterable over the collection.
  - reverseIterable
```
public static <T> Iterable<T> reverseIterable(T[] c)
```
    Returns a reverse iterable over the specified array.
    
    Parameters:
    
    c - The collection to iterate over.
    
    Returns:
    
    An iterable over the collection.
  - iterable
```
public static <E> Iterable<E> iterable(Enumeration<E> e)
```
    Returns an iterable over the specified enumeration.
    
    Parameters:
    
    e - The collection to iterate over.
    
    Returns:
    
    An iterable over the enumeration.
  - unmodifiableList
```
public static <T> List<T> unmodifiableList(List<T> l)
```
    Creates an unmodifiable list from the specified list.
    
    Parameters:
    
    l - The collection to copy from.
    
    Returns:
    
    An unmodifiable view of the list, or a Collections.emptyList() if the list was empty or null.
  - unmodifiableList
```
public static <T> List<T> unmodifiableList(T[] l)
```
    Creates an unmodifiable list from the specified array.
    
    Parameters:
    
    l - The collection to copy from.
    
    Returns:
    
    An unmodifiable view of the list, or a Collections.emptyList() if the list was empty or null.
  - immutableList
```
public static <T> List<T> immutableList(Collection<T> l)
```
    Creates an immutable list from the specified collection.
    
    Parameters:
    
    l - The collection to copy from.
    
    Returns:
    
    An unmodifiable ArrayList copy of the collection, or a Collections.emptyList() if the collection was empty or null.
  - immutableList
```
public static <T> List<T> immutableList(T[] l)
```
    Creates an immutable list from the specified array.
    
    Parameters:
    
    l - The array to copy from.
    
    Returns:
    
    An unmodifiable ArrayList copy of the collection, or a Collections.emptyList() if the collection was empty or null.
  - immutableMap
```
public static <K,V> Map<K,V> immutableMap(Map<K,V> m)
```
    Creates an immutable map from the specified map.
    
    Parameters:
    
    m - The map to copy from.
    
    Returns:
    
    An unmodifiable LinkedHashMap copy of the collection, or a Collections.emptyMap() if the collection was empty or null.
  - unmodifiableMap
```
public static <K,V> Map<K,V> unmodifiableMap(Map<K,V> m)
```
    Creates an unmodifiable map from the specified map.
    
    Parameters:
    
    m - The map to copy from.
    
    Returns:
    
    An unmodifiable view of the collection, or a Collections.emptyMap() if the collection was empty or null.
  - addToList
```
public static <T> List<T> addToList(List<T> appendTo,
                                    Object[] values,
                                    Class<T> type,
                                    Type... args)
```
    Adds a set of values to an existing list.
    
    Parameters:
    
    appendTo - The list to append to.
    If null, a new ArrayList will be created.
    
    values - The values to add.
    
    type - The data type of the elements.
    
    args - The generic type arguments of the data type.
    
    Returns:
    
    The converted value, or null if the input was null.
  - addToMap
```
public static <K,V> Map<K,V> addToMap(Map<K,V> appendTo,
                                      Object[] values,
                                      Class<K> keyType,
                                      Class<V> valueType,
                                      Type... valueTypeArgs)
```
    Adds a set of values to an existing map.
    
    Parameters:
    
    appendTo - The map to append to.
    If null, a new LinkedHashMap will be created.
    
    values - The values to add.
    
    keyType - The data type of the keys.
    
    valueType - The data type of the values.
    
    valueTypeArgs - The generic type arguments of the data type of the values.
    
    Returns:
    
    The converted value, or null if the input was null.
  - newList
```
public static <T> List<T> newList(Collection<T> val)
```
    Creates a new list from the specified collection.
    
    Parameters:
    
    val - The value to copy from.
    
    Returns:
    
    A new ArrayList, or null if the input was null.
  - addToList
```
public static <T> List<T> addToList(List<T> l,
                                    Collection<T> val)
```
    Copies the specified values into an existing list.
    
    Parameters:
    
    l - The list to add to.
    If null, a new ArrayList will be created.
    
    val - The values to add.
    
    Returns:
    
    The list with values copied into it.
  - newMap
```
public static <K,V> Map<K,V> newMap(Map<K,V> val)
```
    Creates a new map from the specified map.
    
    Parameters:
    
    val - The value to copy from.
    
    Returns:
    
    A new LinkedHashMap, or null if the input was null.
  - addToMap
```
public static <K,V> Map<K,V> addToMap(Map<K,V> m,
                                      Map<K,V> val)
```
    Copies the specified values into an existing map.
    
    Parameters:
    
    m - The map to add to.
    If null, a new LinkedHashMap will be created.
    
    val - The values to add.
    
    Returns:
    
    The list with values copied into it.
  - addToMap
```
public static <K,V> Map<K,V> addToMap(Map<K,V> m,
                                      K key,
                                      V value)
```
    Adds a single entry into an existing map.
    
    Parameters:
    
    m - The map to add to.
    If null, a new LinkedHashMap will be created.
    
    key - The entry key.
    
    value - The entry value.
    
    Returns:
    
    The list with values copied into it.
  - newSortedMap
```
public static <K,V> Map<K,V> newSortedMap(Map<K,V> val,
                                          Comparator<K> comparator)
```
    Creates a new map from the specified map.
    
    Parameters:
    
    val - The value to copy from.
    
    comparator - The key comparator to use, or null to use natural ordering.
    
    Returns:
    
    A new LinkedHashMap, or null if the input was null.
  - newSortedCaseInsensitiveSet
```
public static Set<String> newSortedCaseInsensitiveSet(String... values)
```
    Creates a case-insensitive ordered set out of the specified string values.
    
    Parameters:
    
    values - The values to populate the set with.
    
    Returns:
    
    A new ordered set.
  - newSortedCaseInsensitiveSet
```
public static Set<String> newSortedCaseInsensitiveSet(String values)
```
    Creates a case-insensitive ordered set out of the specified string values.
    
    Parameters:
    
    values - A comma-delimited list of the values to populate the set with.
    
    Returns:
    
    A new ordered set.
  - newUnmodifiableSortedCaseInsensitiveSet
```
public static Set<String> newUnmodifiableSortedCaseInsensitiveSet(String values)
```
    Same as newSortedCaseInsensitiveSet(String) but makes the set unmodifiable.
    
    Parameters:
    
    values - A comma-delimited list of the values to populate the set with.
    
    Returns:
    
    A new ordered set.
  - addToSortedMap
```
public static <K,V> Map<K,V> addToSortedMap(Map<K,V> m,
                                            Map<K,V> val,
                                            Comparator<K> comparator)
```
    Copies the specified values into an existing map.
    
    Parameters:
    
    m - The map to add to.
    If null, a new LinkedHashMap will be created.
    
    val - The values to add.
    
    comparator - The key comparator to use, or null to use natural ordering.
    
    Returns:
    
    The list with values copied into it.
  - addToSortedMap
```
public static <K,V> Map<K,V> addToSortedMap(Map<K,V> m,
                                            K key,
                                            V value,
                                            Comparator<K> comparator)
```
    Adds a single entry into an existing map.
    
    Parameters:
    
    m - The map to add to.
    If null, a new LinkedHashMap will be created.
    
    key - The entry key.
    
    value - The entry value.
    
    comparator - The key comparator to use, or null to use natural ordering.
    
    Returns:
    
    The list with values copied into it.
  - newUnmodifiableHashSet
```
@SafeVarargs
public static <T> Set<T> newUnmodifiableHashSet(T... values)
```
    Converts the specified arguments into an unmodifiable HashSet.
    
    Parameters:
    
    values - The entries to populate the hashset with.
    
    Returns:
    
    A new HashSet populated with the specified arguments.
  - newHashSet
```
@SafeVarargs
public static <T> Set<T> newHashSet(T... values)
```
    Converts the specified arguments into a modifiable HashSet.
    
    Parameters:
    
    values - The entries to populate the hashset with.
    
    Returns:
    
    A new HashSet populated with the specified arguments.
  - newUnmodifiableLinkedHashSet
```
@SafeVarargs
public static <T> Set<T> newUnmodifiableLinkedHashSet(T... values)
```
    Converts the specified arguments into an unmodifiable LinkedHashSet.
    
    Parameters:
    
    values - The entries to populate the hashset with.
    
    Returns:
    
    A new LinkedHashSet populated with the specified arguments.
  - newLinkedHashSet
```
@SafeVarargs
public static <T> Set<T> newLinkedHashSet(T... values)
```
    Converts the specified arguments into a modifiable LinkedHashSet.
    
    Parameters:
    
    values - The entries to populate the hashset with.
    
    Returns:
    
    A new LinkedHashSet populated with the specified arguments.
  - emptySet
```
public static <T> Set<T> emptySet()
```
    Simple passthrough to Collections.emptySet()
    
    Returns:
    
    A new unmodifiable empty set.
  - emptyList
```
public static <T> List<T> emptyList()
```
    Simple passthrough to Collections.emptyList()
    
    Returns:
    
    A new unmodifiable empty list.
  - emptyMap
```
public static <K,V> Map<K,V> emptyMap()
```
    Simple passthrough to Collections.emptyMap()
    
    Returns:
    
    A new unmodifiable empty set.

Class CollectionUtils

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

CollectionUtils

Method Detail

addIfNotNull

addReverse

addReverse

iterable

iterable

reverseIterable

iterable

reverseIterable

iterable

unmodifiableList

unmodifiableList

immutableList

immutableList

immutableMap

unmodifiableMap

addToList

addToMap

newList

addToList

newMap

addToMap

addToMap

newSortedMap

newSortedCaseInsensitiveSet

newSortedCaseInsensitiveSet

newUnmodifiableSortedCaseInsensitiveSet

addToSortedMap

addToSortedMap

newUnmodifiableHashSet

newHashSet

newUnmodifiableLinkedHashSet

newLinkedHashSet

emptySet

emptyList

emptyMap