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java.lang.Object org.garret.consus.Persistent org.garret.consus.POCollection
This class provides a skeletion implementation of the Collection interface to minimize the effort required to implement this interface.
To implement an unmodifiable collection, the programmer needs only to extend this class and provide implementations for the iterator and size methods. (The iterator returned by the iterator method must implement hasNext and next methods.)
To implement a modifiable collection, the programmer must override the add method in this (which otherwise throws an UnsupportedOperationException), and the iterator returned by the iterator method must implement its own remove method.
Field Summary |
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Fields inherited from class org.garret.consus.Persistent |
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db, oid, PO_DELETED, PO_LOADED, PO_NEW, PO_STUB, state, type |
Method Summary | |
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boolean |
add(java.lang.Object o)
Ensures that this collection contains the specified element (optional operation). |
boolean |
addAll(java.util.Collection c)
Adds all of the elements in the specified collection to this collection (optional operation). |
void |
clear()
Removes all of the elements from this collection (optional operation). |
boolean |
contains(java.lang.Object o)
Returns true if this collection contains the specified element. |
boolean |
containsAll(java.util.Collection c)
Returns true if this collection contains all of the elements in the specified collection. |
boolean |
equals(java.lang.Object o)
Compares the specified object with this list for equality. |
int |
hashCode()
Returns the hash code value for this list. |
boolean |
isEmpty()
Returns true if this collection contains no elements. |
abstract java.util.Iterator |
iterator()
Returns an iterator of the elements contained in this collection. |
boolean |
remove(java.lang.Object o)
Removes a single instance of the specified element from this collection, if it is present (optional operation). |
boolean |
removeAll(java.util.Collection c)
Removes from this collection all of the elements that are contained in the specified collection (optional operation). |
boolean |
retainAll(java.util.Collection c)
Retains only the elements in this collection that are contained in the specified collection (optional operation). |
abstract int |
size()
Returns the number of elements in this collection. |
java.lang.Object[] |
toArray()
Returns an array containing all of the elements in this collection. |
java.lang.Object[] |
toArray(java.lang.Object[] a)
Returns an array with a runtime type of the specified array and that contains all of the elements in this collection. |
java.lang.String |
toString()
Returns a string representation of this collection. |
Methods inherited from class org.garret.consus.Persistent |
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assignOID, become, beginUpdate, endUpdate, get, get, getOid, getOid, getRef, getRef, isDeleted, isLoaded, isNew, load, loadClosure, loadComponents, lock, remove, save, store, store, unget |
Methods inherited from class java.lang.Object |
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getClass, notify, notifyAll, wait, wait, wait |
Method Detail |
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public boolean add(java.lang.Object o)
This implementation always throws an UnsupportedOperationException.
add
in interface java.util.Collection
o
- element whose presence in this collection is to be ensured.
java.lang.UnsupportedOperationException
- if the add method is not
supported by this collection.
java.lang.NullPointerException
- if this collection does not permit
null elements, and the specified element is
null.
java.lang.ClassCastException
- if the class of the specified element
prevents it from being added to this collection.
java.lang.IllegalArgumentException
- if some aspect of this element
prevents it from being added to this collection.public boolean addAll(java.util.Collection c)
This implementation iterates through the specified collection, and adds each object returned by the iterator to this collection, in turn.
Note that this implementation will throw an UnsupportedOperationException unless add it is overridden.
addAll
in interface java.util.Collection
c
- collection whose elements are to be added to this collection.
java.lang.UnsupportedOperationException
- if the addAll method is
not supported by this collection.add(Object)
public void clear()
This implementation iterates through the collection, removing each element using the Iterator.remove operation. Most implementations will probably choose to override this method for efficiency.
Note that this implementation will throw an UnsupportedOperationException if the iterator returned by this collection's iterator method does not implement the remove method.
clear
in interface java.util.Collection
java.lang.UnsupportedOperationException
- if the remove method is
not supported by this collection.public boolean contains(java.lang.Object o)
This implementation iterates over the elements in the collection, checking each element in turn for equality with the specified element.
contains
in interface java.util.Collection
o
- object to be checked for existance in this collection.
public boolean containsAll(java.util.Collection c)
This implementation iterates over the specified collection, checking each element returned by the iterator in turn to see if it's contained in this collection. If all elements are found then true is returned, otherwise false.
containsAll
in interface java.util.Collection
c
- collection to be checked for containment in this collection.
contains(Object)
public boolean equals(java.lang.Object o)
This implementation first checks that the specified object is in this list. If yes, it returns true; if not, it checks if the specified object is a list. If not, it returns false; if yes, it iterates through both lists, comparing corresponding pairs of elements. If any comparison returns false, this method returns false. If either iterator runs out of elements before the other, it returns false (as the lists are of unequal length). Otherwise it returns true when the iteration is completed.
equals
in interface java.util.Collection
equals
in class java.lang.Object
o
- the object to be compared for equality with this list.
public int hashCode()
This implementation uses the code that is used to define the list hash function in the documentation for the List.hashCode method.
hashCode
in interface java.util.Collection
hashCode
in class java.lang.Object
public boolean isEmpty()
This implementation returns size() == 0.
isEmpty
in interface java.util.Collection
public abstract java.util.Iterator iterator()
iterator
in interface java.util.Collection
public boolean remove(java.lang.Object o)
This implementation iterates over the collection looking for the specified element. If it finds the element, it removes the element from the collection using the iterator's remove method.
Note that this implementation throws an UnsupportedOperationException if the iterator returned by this collection's iterator method does not implement the remove method.
remove
in interface java.util.Collection
o
- element to be removed from this collection, if present.
java.lang.UnsupportedOperationException
- if the remove method is
not supported by this collection.public boolean removeAll(java.util.Collection c)
This implementation iterates through this collection, checking each element returned by the iterator, to see if it exists in the specified collection. If it does exist, it is removed from this collection with the iterator's remove method.
Note that this implementation will throw an UnsupportedOperationException if the iterator returned by the iterator method does not implement the remove method.
removeAll
in interface java.util.Collection
c
- elements to be removed from this collection.
java.lang.UnsupportedOperationException
- removeAll is not supported
by this collection.remove(Object)
,
contains(Object)
public boolean retainAll(java.util.Collection c)
This implementation iterates through this collection, checking each element, returned by the iterator, to see if it exists in the specified collection. If it does not exist, it is removed from this collection with the iterator's remove method.
Note that this implementation will throw an UnsupportedOperationException if the iterator returned by the iterator method does not implement the remove method.
retainAll
in interface java.util.Collection
java.lang.UnsupportedOperationException
- if the retainAll method
is not supported by this collection.remove(Object)
,
contains(Object)
public abstract int size()
size
in interface java.util.Collection
public java.lang.Object[] toArray()
This implementation allocates the array to be returned, and iterates over the elements in the collection, storing each object reference in the next consecutive element of the array, starting with element 0.
toArray
in interface java.util.Collection
public java.lang.Object[] toArray(java.lang.Object[] a)
If the collection fits in the specified array with room to spare (i.e. the array has more elements than the collection), 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 collection only if the caller knows that the collection does not contain any null elements.)
If this collection makes any guarantees as to what order its elements are returned by its iterator, this method must return the elements in the same order.
This implementation checks if the array is large enough to contain the collection. If not, it allocates a new array of the correct size and type (using reflection). Then it iterates over the collection, storing each object reference in the next consecutive element of the array, starting with element 0. If the array is larger than the collection, a null is stored in the first location after the end of the collection.
toArray
in interface java.util.Collection
a
- the array into which the elements of the collection are to
be stored, if it is big enough; otherwise, a new array of the
same runtime type is allocated for this purpose.
java.lang.NullPointerException
- if the specified array is null.
java.lang.ArrayStoreException
- if the runtime type of the specified array
is not a supertype of the runtime type of every element in this
collection.public java.lang.String toString()
This implementation creates an empty string buffer, appends a left square bracket, and iterates through the collection appending the string representation of each element in turn. After appending each element, except the last, the string ", " is appended. Finally a right bracket is appended. A string is obtained from the string buffer and returned.
toString
in class Persistent
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