Package Summary Overview Summary

### class:ArrayList [NONE]
- Type Parameters: `E` - the type of elements in this list All Implemented Interfaces: `Serializable`, `Cloneable`, `Iterable<E>`, `Collection<E>`, `List<E>`, `RandomAccess` Direct Known Subclasses: `AttributeList`, `RoleList`, `RoleUnresolvedList`
                                                                                      public class ArrayList<E>
      extends AbstractList<E>
      implements List<E>, RandomAccess, Cloneable, Serializable
  Resizable-array implementation of the `List` interface. Implements all optional list operations, and permits all elements, including `null`. In addition to implementing the `List` interface, this class provides methods to manipulate the size of the array that is used internally to store the list. (This class is roughly equivalent to `Vector`, except that it is unsynchronized.) The `size`, `isEmpty`, `get`, `set`, `iterator`, and `listIterator` operations run in constant time. The `add` operation runs in amortized constant time , that is, adding n elements requires O(n) time. All of the other operations run in linear time (roughly speaking). The constant factor is low compared to that for the `LinkedList` implementation. Each `ArrayList` instance has a capacity. The capacity is the size of the array used to store the elements in the list. It is always at least as large as the list size. As elements are added to an ArrayList, its capacity grows automatically. The details of the growth policy are not specified beyond the fact that adding an element has constant amortized time cost. An application can increase the capacity of an `ArrayList` instance before adding a large number of elements using the `ensureCapacity` operation. This may reduce the amount of incremental reallocation. Note that this implementation is not synchronized. If multiple threads access an `ArrayList` instance concurrently, and at least one of the threads modifies the list structurally, it must be synchronized externally. (A structural modification is any operation that adds or deletes one or more elements, or explicitly resizes the backing array; merely setting the value of an element is not a structural modification.) This is typically accomplished by synchronizing on some object that naturally encapsulates the list. If no such object exists, the list should be "wrapped" using the `Collections.synchronizedList` method. This is best done at creation time, to prevent accidental unsynchronized access to the list:
         List list = Collections.synchronizedList(new ArrayList(...));
The iterators returned by this class's `iterator` and `listIterator` methods are fail-fast: if the list is structurally modified at any time after the iterator is created, in any way except through the iterator's own `remove` or `add` methods, the iterator will throw a `ConcurrentModificationException`. Thus, in the face of concurrent modification, the iterator fails quickly and cleanly, rather than risking arbitrary, non-deterministic behavior at an undetermined time in the future. Note that the fail-fast behavior of an iterator cannot be guaranteed as it is, generally speaking, impossible to make any hard guarantees in the presence of unsynchronized concurrent modification. Fail-fast iterators throw `ConcurrentModificationException` on a best-effort basis. Therefore, it would be wrong to write a program that depended on this exception for its correctness: the fail-fast behavior of iterators should be used only to detect bugs. This class is a member of the Java Collections Framework . Since: 1.2 See Also: `Collection`, `List`, `LinkedList`, `Vector`, Serialized Form

### constructor:<init>(int) [NONE]
- #### ArrayList
      public ArrayList​(int initialCapacity)
Constructs an empty list with the specified initial capacity. Parameters: `initialCapacity` - the initial capacity of the list Throws: `IllegalArgumentException` - if the specified initial capacity is negative

### constructor:<init>() [NONE]
- #### ArrayList
      public ArrayList()
Constructs an empty list with an initial capacity of ten.

### constructor:<init>(java.util.Collection) [NONE]
- #### ArrayList
                                                                                                      public ArrayList​(Collection<? extends E> c)
Constructs a list containing the elements of the specified collection, in the order they are returned by the collection's iterator. Parameters: `c` - the collection whose elements are to be placed into this list Throws: `NullPointerException` - if the specified collection is null

### method:trimToSize() [NONE]
- #### trimToSize
      public void trimToSize()
Trims the capacity of this `ArrayList` instance to be the list's current size. An application can use this operation to minimize the storage of an `ArrayList` instance.

### method:ensureCapacity(int) [NONE]
- #### ensureCapacity
      public void ensureCapacity​(int minCapacity)
Increases the capacity of this `ArrayList` instance, if necessary, to ensure that it can hold at least the number of elements specified by the minimum capacity argument. Parameters: `minCapacity` - the desired minimum capacity

### method:size() [NONE]
- #### size
      public int size()
Returns the number of elements in this list. Specified by: `size` in interface `Collection<E>` Specified by: `size` in interface `List<E>` Returns: the number of elements in this list

### method:isEmpty() [NONE]
- #### isEmpty
      public boolean isEmpty()
Returns `true` if this list contains no elements. Specified by: `isEmpty` in interface `Collection<E>` Specified by: `isEmpty` in interface `List<E>` Overrides: `isEmpty` in class `AbstractCollection<E>` Returns: `true` if this list contains no elements

### method:contains(java.lang.Object) [NONE]
- #### contains
                                                                                                      public boolean contains​(Object o)
Returns `true` if this list contains the specified element. More formally, returns `true` if and only if this list contains at least one element `e` such that `Objects.equals(o, e)` . Specified by: `contains` in interface `Collection<E>` Specified by: `contains` in interface `List<E>` Overrides: `contains` in class `AbstractCollection<E>` Parameters: `o` - element whose presence in this list is to be tested Returns: `true` if this list contains the specified element

### method:indexOf(java.lang.Object) [NONE]
- #### indexOf
                                                                                                      public int indexOf​(Object o)
Returns the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element. More formally, returns the lowest index `i` such that `Objects.equals(o, get(i))` , or -1 if there is no such index. Specified by: `indexOf` in interface `List<E>` Overrides: `indexOf` in class `AbstractList<E>` Parameters: `o` - element to search for Returns: the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element

### method:lastIndexOf(java.lang.Object) [NONE]
- #### lastIndexOf
                                                                                                      public int lastIndexOf​(Object o)
Returns the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element. More formally, returns the highest index `i` such that `Objects.equals(o, get(i))` , or -1 if there is no such index. Specified by: `lastIndexOf` in interface `List<E>` Overrides: `lastIndexOf` in class `AbstractList<E>` Parameters: `o` - element to search for Returns: the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element

### method:clone() [NONE]
- #### clone
                                                                                                      public Object clone()
Returns a shallow copy of this `ArrayList` instance. (The elements themselves are not copied.) Overrides: `clone` in class `Object` Returns: a clone of this `ArrayList` instance See Also: `Cloneable`

### method:toArray() [NONE]
- #### toArray
                                                                                                      public Object[] toArray()
Returns an array containing all of the elements in this list in proper sequence (from first to last element). The returned array will be "safe" in that no references to it are maintained by this list. (In other words, this method must allocate a new array). The caller is thus free to modify the returned array. This method acts as bridge between array-based and collection-based APIs. Specified by: `toArray` in interface `Collection<E>` Specified by: `toArray` in interface `List<E>` Overrides: `toArray` in class `AbstractCollection<E>` Returns: an array containing all of the elements in this list in proper sequence See Also: `Arrays.asList(Object[])`

### method:toArray(T[]) [NONE]
- #### toArray
      public <T> T[] toArray​(T[] a)
Returns an array containing all of the elements in this list in proper sequence (from first to last element); the runtime type of the returned array is that of the specified array. If the list fits in the specified array, it is returned therein. Otherwise, a new array is allocated with the runtime type of the specified array and the size of this list. If the list fits in the specified array with room to spare (i.e., the array has more elements than the list), the element in the array immediately following the end of the collection is set to `null`. (This is useful in determining the length of the list only if the caller knows that the list does not contain any null elements.) Specified by: `toArray` in interface `Collection<E>` Specified by: `toArray` in interface `List<E>` Overrides: `toArray` in class `AbstractCollection<E>` Type Parameters: `T` - the component type of the array to contain the collection Parameters: `a` - the array into which the elements of the list are to be stored, if it is big enough; otherwise, a new array of the same runtime type is allocated for this purpose. Returns: an array containing the elements of the list Throws: `ArrayStoreException` - if the runtime type of the specified array is not a supertype of the runtime type of every element in this list `NullPointerException` - if the specified array is null

### method:get(int) [NONE]
- #### get
                                                                                                      public E get​(int index)
Returns the element at the specified position in this list. Specified by: `get` in interface `List<E>` Specified by: `get` in class `AbstractList<E>` Parameters: `index` - index of the element to return Returns: the element at the specified position in this list Throws: `IndexOutOfBoundsException` - if the index is out of range (`index < 0 || index >= size()` )

### method:set(int,E) [NONE]
- #### set
                                                                                                      public E set​(int index,
                   E element)
Replaces the element at the specified position in this list with the specified element. Specified by: `set` in interface `List<E>` Overrides: `set` in class `AbstractList<E>` Parameters: `index` - index of the element to replace `element` - element to be stored at the specified position Returns: the element previously at the specified position Throws: `IndexOutOfBoundsException` - if the index is out of range (`index < 0 || index >= size()` )

### method:add(E) [NONE]
- #### add
                                                                                                      public boolean add​(E e)
Appends the specified element to the end of this list. Specified by: `add` in interface `Collection<E>` Specified by: `add` in interface `List<E>` Overrides: `add` in class `AbstractList<E>` Parameters: `e` - element to be appended to this list Returns: `true` (as specified by `Collection.add(E)`)

### method:add(int,E) [NONE]
- #### add
                                                                                                      public void add​(int index,
                      E element)
Inserts the specified element at the specified position in this list. Shifts the element currently at that position (if any) and any subsequent elements to the right (adds one to their indices). Specified by: `add` in interface `List<E>` Overrides: `add` in class `AbstractList<E>` Parameters: `index` - index at which the specified element is to be inserted `element` - element to be inserted Throws: `IndexOutOfBoundsException` - if the index is out of range (`index < 0 || index > size()` )

### method:remove(int) [NONE]
- #### remove
                                                                                                      public E remove​(int index)
Removes the element at the specified position in this list. Shifts any subsequent elements to the left (subtracts one from their indices). Specified by: `remove` in interface `List<E>` Overrides: `remove` in class `AbstractList<E>` Parameters: `index` - the index of the element to be removed Returns: the element that was removed from the list Throws: `IndexOutOfBoundsException` - if the index is out of range (`index < 0 || index >= size()` )

### method:remove(java.lang.Object) [NONE]
- #### remove
                                                                                                      public boolean remove​(Object o)
Removes the first occurrence of the specified element from this list, if it is present. If the list does not contain the element, it is unchanged. More formally, removes the element with the lowest index `i` such that `Objects.equals(o, get(i))` (if such an element exists). Returns `true` if this list contained the specified element (or equivalently, if this list changed as a result of the call). Specified by: `remove` in interface `Collection<E>` Specified by: `remove` in interface `List<E>` Overrides: `remove` in class `AbstractCollection<E>` Parameters: `o` - element to be removed from this list, if present Returns: `true` if this list contained the specified element

### method:clear() [NONE]
- #### clear
      public void clear()
Removes all of the elements from this list. The list will be empty after this call returns. Specified by: `clear` in interface `Collection<E>` Specified by: `clear` in interface `List<E>` Overrides: `clear` in class `AbstractList<E>`

### method:addAll(java.util.Collection) [NONE]
- #### addAll
                                                                                                      public boolean addAll​(Collection<? extends E> c)
Appends all of the elements in the specified collection to the end of this list, in the order that they are returned by the specified collection's Iterator. The behavior of this operation is undefined if the specified collection is modified while the operation is in progress. (This implies that the behavior of this call is undefined if the specified collection is this list, and this list is nonempty.) Specified by: `addAll` in interface `Collection<E>` Specified by: `addAll` in interface `List<E>` Overrides: `addAll` in class `AbstractCollection<E>` Parameters: `c` - collection containing elements to be added to this list Returns: `true` if this list changed as a result of the call Throws: `NullPointerException` - if the specified collection is null See Also: `AbstractCollection.add(Object)`

### method:addAll(int,java.util.Collection) [NONE]
- #### addAll
                                                                                                      public boolean addAll​(int index,
                            Collection<? extends E> c)
Inserts all of the elements in the specified collection into this list, starting at the specified position. Shifts the element currently at that position (if any) and any subsequent elements to the right (increases their indices). The new elements will appear in the list in the order that they are returned by the specified collection's iterator. Specified by: `addAll` in interface `List<E>` Overrides: `addAll` in class `AbstractList<E>` Parameters: `index` - index at which to insert the first element from the specified collection `c` - collection containing elements to be added to this list Returns: `true` if this list changed as a result of the call Throws: `IndexOutOfBoundsException` - if the index is out of range (`index < 0 || index > size()` ) `NullPointerException` - if the specified collection is null

### method:removeRange(int,int) [NONE]
- #### removeRange
      protected void removeRange​(int fromIndex,
                                 int toIndex)
Removes from this list all of the elements whose index is between `fromIndex`, inclusive, and `toIndex`, exclusive. Shifts any succeeding elements to the left (reduces their index). This call shortens the list by `(toIndex - fromIndex)` elements. (If `toIndex==fromIndex`, this operation has no effect.) Overrides: `removeRange` in class `AbstractList<E>` Parameters: `fromIndex` - index of first element to be removed `toIndex` - index after last element to be removed Throws: `IndexOutOfBoundsException` - if `fromIndex` or `toIndex` is out of range (`fromIndex < 0 || toIndex > size() || toIndex < fromIndex` )

### method:removeAll(java.util.Collection) [NONE]
- #### removeAll
                                                                                                      public boolean removeAll​(Collection<?> c)
Removes from this list all of its elements that are contained in the specified collection. Specified by: `removeAll` in interface `Collection<E>` Specified by: `removeAll` in interface `List<E>` Overrides: `removeAll` in class `AbstractCollection<E>` Parameters: `c` - collection containing elements to be removed from this list Returns: `true` if this list changed as a result of the call Throws: `ClassCastException` - if the class of an element of this list is incompatible with the specified collection (optional) `NullPointerException` - if this list contains a null element and the specified collection does not permit null elements (optional), or if the specified collection is null See Also: `Collection.contains(Object)`

### method:retainAll(java.util.Collection) [NONE]
- #### retainAll
                                                                                                      public boolean retainAll​(Collection<?> c)
Retains only the elements in this list that are contained in the specified collection. In other words, removes from this list all of its elements that are not contained in the specified collection. Specified by: `retainAll` in interface `Collection<E>` Specified by: `retainAll` in interface `List<E>` Overrides: `retainAll` in class `AbstractCollection<E>` Parameters: `c` - collection containing elements to be retained in this list Returns: `true` if this list changed as a result of the call Throws: `ClassCastException` - if the class of an element of this list is incompatible with the specified collection (optional) `NullPointerException` - if this list contains a null element and the specified collection does not permit null elements (optional), or if the specified collection is null See Also: `Collection.contains(Object)`

### method:listIterator(int) [NONE]
- #### listIterator
                                                                                                      public ListIterator<E> listIterator​(int index)
Returns a list iterator over the elements in this list (in proper sequence), starting at the specified position in the list. The specified index indicates the first element that would be returned by an initial call to `next`. An initial call to `previous` would return the element with the specified index minus one. The returned list iterator is fail-fast. Specified by: `listIterator` in interface `List<E>` Overrides: `listIterator` in class `AbstractList<E>` Parameters: `index` - index of the first element to be returned from the list iterator (by a call to `next`) Returns: a list iterator over the elements in this list (in proper sequence), starting at the specified position in the list Throws: `IndexOutOfBoundsException` - if the index is out of range (`index < 0 || index > size()` )

### method:listIterator() [NONE]
- #### listIterator
                                                                                                      public ListIterator<E> listIterator()
Returns a list iterator over the elements in this list (in proper sequence). The returned list iterator is fail-fast. Specified by: `listIterator` in interface `List<E>` Overrides: `listIterator` in class `AbstractList<E>` Returns: a list iterator over the elements in this list (in proper sequence) See Also: `listIterator(int)`

### method:iterator() [NONE]
- #### iterator
                                                                                                      public Iterator<E> iterator()
Returns an iterator over the elements in this list in proper sequence. The returned iterator is fail-fast. Specified by: `iterator` in interface `Collection<E>` Specified by: `iterator` in interface `Iterable<E>` Specified by: `iterator` in interface `List<E>` Overrides: `iterator` in class `AbstractList<E>` Returns: an iterator over the elements in this list in proper sequence

### method:subList(int,int) [NONE]
- #### subList
                                                                                                      public List<E> subList​(int fromIndex,
                             int toIndex)
  Returns a view of the portion of this list between the specified `fromIndex`, inclusive, and `toIndex`, exclusive. (If `fromIndex` and `toIndex` are equal, the returned list is empty.) The returned list is backed by this list, so non-structural changes in the returned list are reflected in this list, and vice-versa. The returned list supports all of the optional list operations. This method eliminates the need for explicit range operations (of the sort that commonly exist for arrays). Any operation that expects a list can be used as a range operation by passing a subList view instead of a whole list. For example, the following idiom removes a range of elements from a list:
            list.subList(from, to).clear();
Similar idioms may be constructed for `indexOf(Object)` and `lastIndexOf(Object)`, and all of the algorithms in the `Collections` class can be applied to a subList. The semantics of the list returned by this method become undefined if the backing list (i.e., this list) is structurally modified in any way other than via the returned list. (Structural modifications are those that change the size of this list, or otherwise perturb it in such a fashion that iterations in progress may yield incorrect results.) Specified by: `subList` in interface `List<E>` Overrides: `subList` in class `AbstractList<E>` Parameters: `fromIndex` - low endpoint (inclusive) of the subList `toIndex` - high endpoint (exclusive) of the subList Returns: a view of the specified range within this list Throws: `IndexOutOfBoundsException` - if an endpoint index value is out of range `(fromIndex < 0 || toIndex > size)` `IllegalArgumentException` - if the endpoint indices are out of order `(fromIndex > toIndex)`

### method:forEach(java.util.function.Consumer) [NONE]
- #### forEach
                                                                                                      public void forEach​(Consumer<? super E> action)
Description copied from interface: `Iterable` Performs the given action for each element of the `Iterable` until all elements have been processed or the action throws an exception. Actions are performed in the order of iteration, if that order is specified. Exceptions thrown by the action are relayed to the caller. The behavior of this method is unspecified if the action performs side-effects that modify the underlying source of elements, unless an overriding class has specified a concurrent modification policy. Specified by: `forEach` in interface `Iterable<E>` Parameters: `action` - The action to be performed for each element Throws: `NullPointerException` - if the specified action is null

### method:spliterator() [NONE]
- #### spliterator
                                                                                                      public Spliterator<E> spliterator()
Creates a late-binding and fail-fast `Spliterator` over the elements in this list. The `Spliterator` reports `Spliterator.SIZED`, `Spliterator.SUBSIZED`, and `Spliterator.ORDERED`. Overriding implementations should document the reporting of additional characteristic values. Specified by: `spliterator` in interface `Collection<E>` Specified by: `spliterator` in interface `Iterable<E>` Specified by: `spliterator` in interface `List<E>` Returns: a `Spliterator` over the elements in this list Since: 1.8

### method:removeIf(java.util.function.Predicate) [NONE]
- #### removeIf
                                                                                                      public boolean removeIf​(Predicate<? super E> filter)
Description copied from interface: `Collection` Removes all of the elements of this collection that satisfy the given predicate. Errors or runtime exceptions thrown during iteration or by the predicate are relayed to the caller. Specified by: `removeIf` in interface `Collection<E>` Parameters: `filter` - a predicate which returns `true` for elements to be removed Returns: `true` if any elements were removed Throws: `NullPointerException` - if the specified filter is null