Contents | Package | Class | Tree | Deprecated | Index | Help | Java 1.2 Beta 3 | ||
PREV | NEXT | SHOW LISTS | HIDE LISTS |
java.lang.Object | +----java.util.AbstractCollection | +----java.util.AbstractList
To implement an unmodifiable List, the programmer needs only to extend this class and provide implementations for the get(int index) and size() methods.
To implement a modifiable List, the programmer must additionally override the set(int index, Object element) method (which otherwise throws an UnsupportedOperationException. If the List is variable-size the programmer must additionally override the add(int index, Object element) and remove(int index) 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 listIterator are implemented by this class, on top the "random access" methods: get(int index), set(int index, Object element), set(int index, Object element), add(int index, Object element) and remove(int index).
The documentation for each non-abstract methods 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.
Field Summary | |
int | modCount
|
Constructor Summary | |
AbstractList()
|
Method Summary | |
boolean | add(Object o)
|
void | add(int index,
Object element)
|
boolean | addAll(int index,
Collection c)
|
boolean | equals(Object o)
|
Object | get(int index)
|
int | hashCode()
|
int | indexOf(Object o)
|
int | indexOf(Object o,
int index)
|
Iterator | iterator()
|
int | lastIndexOf(Object o)
|
int | lastIndexOf(Object o,
int index)
|
ListIterator | listIterator()
|
ListIterator | listIterator(int index)
|
Object | remove(int index)
|
void | removeRange(int fromIndex,
int toIndex)
|
Object | set(int index,
Object element)
|
Methods inherited from class java.util.AbstractCollection |
add, addAll, clear, contains, containsAll, isEmpty, iterator, remove, removeAll, retainAll, size, toArray, toArray, toString |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
protected transient int modCount
This field is used by the the Iterator and ListIterator implementation returned by the iterator and listIterator methods. If the value of this field changes unexpectedly, the Iterator (or ListIterator) 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 ListIterators), then it merely has to increment this field in its add(int, Object) 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, Object) or remove(int) must add no more than one to this field, or the Iterators (and ListIterators) will throw bogus ConcurrentModificationExceptions. If an implementation does not wish to provide fail-fast Iterators, this field may be ignored.
Constructor Detail |
public AbstractList()
Method Detail |
public boolean add(Object o)
This implementation calls add(size(), o)
.
Note that this implementation will throw an UnsupportedOperationException unless add(int, Object) is overridden.
o
- element to be appended to this List.
public abstract Object get(int index)
index
- index of element to return.
public Object set(int index, Object element)
This implementation always throws an UnsupportedOperationException.
index
- index of element to replace.
element
- element to be stored at the specified position.
public void add(int index, Object element)
This implementation always throws an UnsupportedOperationException.
index
- index at which the specified element is to be inserted.
element
- element to be inserted.
public Object remove(int index)
This implementation always throws an UnsupportedOperationException.
index
- the index of the element to removed.
public int indexOf(Object o)
(o==null ? get(i)==null : o.equals(get(i)))
,
or -1 if there is no such index.
This implementation returns indexOf(o, 0)
.
o
- element to search for.
public int indexOf(Object o, int index)
(o==null ? get(i)==null :
o.equals(get(i)))
, or -1 if there is no such index.
This implementation first gets a ListIterator pointing to the indexed element (with listIterator(index)). Then, it iterates over the remainder of the List until the specified element is found or the end of the List is reached.
o
- element to search for.
index
- initial position to search for the specified element.
public int lastIndexOf(Object o)
(o==null ? get(i)==null : o.equals(get(i)))
,
or -1 if there is no such index.
This implementation returns lastIndexOf(o, size()-1)
.
o
- element to search for.
public int lastIndexOf(Object o, int index)
(o==null ? get(i)==null :
o.equals(get(i)))
, or -1 if there is no such index.
This implementation first gets a ListIterator pointing to the element after the indexed element (with listIterator(index)). Then, it iterates backwards over the list until the specified element is found, or the beginning of the list is reached.
o
- element to search for.
index
- initial position to search for the specified element.
public void removeRange(int fromIndex, int toIndex)
This implementation first checks to see that the indices are in range. Then, it calls remove(fromIndex) repeatedly, toIndex-fromIndex times. Many implementations will override this method for efficiency.
Note that this implementation will throw an UnsupportedOperationException unless remove(int) is overridden.
fromIndex
- index of first element to be removed.
toIndex
- index after last element to be removed.
public boolean addAll(int index, Collection c)
This implementation gets an Iterator over the specified Collection and iterates over it, inserting the elements obtained from the Iterator into this List at the appropriate position, one at a time, using add(int, Object). Many implementations will override this method for efficiency.
Note that this implementation will throw an UnsupportedOperationException unless add(int, Object) is overridden.
index
- index at which to insert first element from the
specified collection.
c
- elements to be inserted into this List.
public Iterator iterator()
This implementation returns a straightforward implementation of the Iterator interface, relying on the the backing List's size(), get(int), and remove(int) methods.
Note that the Iterator returned by this method will throw an UnsupportedOperationException in response to its remove method unless the List's remove(int) method is overridden.
This implementation can be made to throw runtime exceptions in the face of concurrent modification, as described in the specification for the (protected) modCount field.
public ListIterator listIterator()
listIterator(0)
.public ListIterator listIterator(int index)
This implementation returns a straightforward implementation of the ListIterator interface that extends the implementation of the Iterator interface returned by iterator(). The ListIterator implementation relies on the the backing List's get(int), set(int, Object), add(int, Object) and remove(int) methods.
Note that the ListIterator returned by this implementation will throw an UnsupportedOperationException in response to its remove, set and add methods unless the List's remove(int), set(int, Object), and add(int, Object) methods are overridden (respectively).
This implementation can be made to throw runtime exceptions in the face of concurrent modification, as described in the specification for the (protected) modCount field.
index
- index of first element to be returned from the
ListIterator (by a call to getNext).
public boolean equals(Object o)
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.
This implementation first checks if the specified object is this List. If so, it returns true; if not, it checks if the specified object is a List. If not, it returns false; if so, it iterates over both lists, comparing corresponding pairs of elements. If any comparison returns false, this method returns false. If either Iterator runs out of elements before before the other it returns false (as the Lists are of unequal length); otherwise it returns true when the iterations complete.
o
- the Object to be compared for equality with this List.
public int hashCode()
This implementation uses exactly the code that is used to define the List hash function in the documentation for List.hashCode.
Contents | Package | Class | Tree | Deprecated | Index | Help | Java 1.2 Beta 3 | ||
PREV | NEXT | SHOW LISTS | HIDE LISTS |