Java util abstractlist clear

Java util abstractlist clear

This class provides a skeletal implementation of the List interface to minimize the effort required to implement this interface backed by a «random access» data store (such as an array). For sequential access data (such as a linked list), AbstractSequentialList should be used in preference to this class. To implement an unmodifiable list, the programmer needs only to extend this class and provide implementations for the get(int) and size() methods. To implement a modifiable list, the programmer must additionally override the set(int, E) method (which otherwise throws an UnsupportedOperationException ). If the list is variable-size the programmer must additionally override the add(int, E) and remove(int) methods. The programmer should generally provide a void (no argument) and collection constructor, as per the recommendation in the Collection interface specification. Unlike the other abstract collection implementations, the programmer does not have to provide an iterator implementation; the iterator and list iterator are implemented by this class, on top of the «random access» methods: get(int) , set(int, E) , add(int, E) and remove(int) . The documentation for each non-abstract method in this class describes its implementation in detail. Each of these methods may be overridden if the collection being implemented admits a more efficient implementation. This class is a member of the Java Collections Framework.

Field Summary

Constructor Summary

Method Summary

Inserts all of the elements in the specified collection into this list at the specified position (optional operation).

Returns the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element.

Returns the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element.

Returns a list iterator over the elements in this list (in proper sequence), starting at the specified position in the list.

Removes from this list all of the elements whose index is between fromIndex , inclusive, and toIndex , exclusive.

Replaces the element at the specified position in this list with the specified element (optional operation).

Returns a view of the portion of this list between the specified fromIndex , inclusive, and toIndex , exclusive.

Methods declared in class java.util.AbstractCollection

Methods declared in class java.lang.Object

Methods declared in interface java.util.Collection

Methods declared in interface java.lang.Iterable

Methods declared in interface java.util.List

Field Detail

modCount

protected transient int modCount

The number of times this list has been structurally modified. Structural modifications are those that change the size of the list, or otherwise perturb it in such a fashion that iterations in progress may yield incorrect results. This field is used by the iterator and list iterator implementation returned by the iterator and listIterator methods. If the value of this field changes unexpectedly, the iterator (or list iterator) will throw a ConcurrentModificationException in response to the next , remove , previous , set or add operations. This provides fail-fast behavior, rather than non-deterministic behavior in the face of concurrent modification during iteration. Use of this field by subclasses is optional. If a subclass wishes to provide fail-fast iterators (and list iterators), then it merely has to increment this field in its add(int, E) and remove(int) methods (and any other methods that it overrides that result in structural modifications to the list). A single call to add(int, E) or remove(int) must add no more than one to this field, or the iterators (and list iterators) will throw bogus ConcurrentModificationExceptions . If an implementation does not wish to provide fail-fast iterators, this field may be ignored.

Constructor Detail

AbstractList

Method Detail

add

Appends the specified element to the end of this list (optional operation). Lists that support this operation may place limitations on what elements may be added to this list. In particular, some lists will refuse to add null elements, and others will impose restrictions on the type of elements that may be added. List classes should clearly specify in their documentation any restrictions on what elements may be added.

get

set

Replaces the element at the specified position in this list with the specified element (optional operation).

add

Inserts the specified element at the specified position in this list (optional operation). Shifts the element currently at that position (if any) and any subsequent elements to the right (adds one to their indices).

remove

Removes the element at the specified position in this list (optional operation). Shifts any subsequent elements to the left (subtracts one from their indices). Returns the element that was removed from the list.

indexOf

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.

lastIndexOf

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.

clear

Removes all of the elements from this list (optional operation). The list will be empty after this call returns.

addAll

Inserts all of the elements in the specified collection into this list at the specified position (optional operation). 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 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. (Note that this will occur if the specified collection is this list, and it’s nonempty.)

iterator

listIterator

listIterator

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.

subList

public ListE> 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 supported by this list. 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:

Similar idioms may be constructed for indexOf and lastIndexOf , 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.)

equals

Compares the specified object with this list for equality. Returns true if and only if the specified object is also a list, both lists have the same size, and all corresponding pairs of elements in the two lists are equal. (Two elements e1 and e2 are equal if (e1==null ? e2==null : e1.equals(e2)) .) In other words, two lists are defined to be equal if they contain the same elements in the same order.

hashCode

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.) This method is called by the clear operation on this list and its subLists. Overriding this method to take advantage of the internals of the list implementation can substantially improve the performance of the clear operation on this list and its subLists.

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