Java Doc for ListUtils.java in  » Library » Apache-common-Collections » org » apache » commons » collections » Java Source Code / Java DocumentationJava Source Code and Java Documentation

This method is useful for implementing List when you cannot extend AbstractList.

This method is useful for implementing List when you cannot extend AbstractList.

When the index passed to the returned list's List.get(int) get method is greater than the list's size, then the factory will be used to create a new object and that object will be inserted at that index.

For instance:

 Factory factory = new Factory() {
 public Object create() {
 return new Date();
 }
 }
 List lazy = ListUtils.lazyList(new ArrayList(), factory);
 Object obj = lazy.get(3);
 

Each object is passed through the transformer as it is added to the List.

This method is useful for implementing List when you cannot extend AbstractList. The method takes Collection instances to enable other collection types to use the List implementation algorithm.
See Also:   java.util.List.hashCode
Parameters:
  list - the list to generate the hashCode for, may be null the hash code

This method is useful for implementing List when you cannot extend AbstractList. The method takes Collection instances to enable other collection types to use the List implementation algorithm.

The relevant text (slightly paraphrased as this is a static method) is:

Compares the two list objects for equality. Returns true if and only if 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. This definition ensures that the equals method works properly across different implementations of the List interface.

When the index passed to the returned list's List.get(int) get method is greater than the list's size, then the factory will be used to create a new object and that object will be inserted at that index.

For instance:

 Factory factory = new Factory() {
 public Object create() {
 return new Date();
 }
 }
 List lazy = ListUtils.lazyList(new ArrayList(), factory);
 Object obj = lazy.get(3);
 

Only objects that pass the test in the given predicate can be added to the list. Trying to add an invalid object results in an IllegalArgumentException. It is important not to use the original list after invoking this method, as it is a backdoor for adding invalid objects.
Parameters:
  list - the list to predicate, must not be null
Parameters:
  predicate - the predicate for the list, must not be null a predicated list backed by the given list
throws:
  IllegalArgumentException - if the List or Predicate is null

This differs from List.removeAll(Collection) in that cardinality is respected; if list1 contains two occurrences of null and list2 only contains one occurrence, then the returned list will still contain one occurrence.
Parameters:
  list1 - the list to subtract from
Parameters:
  list2 - the list to subtract a new list containing the results
throws:
  NullPointerException - if either list is null

You must manually synchronize on the returned buffer's iterator to avoid non-deterministic behavior:

 List list = ListUtils.synchronizedList(myList);
 synchronized (list) {
 Iterator i = list.iterator();
 while (i.hasNext()) {
 process (i.next());
 }
 }
 

Each object is passed through the transformer as it is added to the List. It is important not to use the original list after invoking this method, as it is a backdoor for adding untransformed objects.
Parameters:
  list - the list to predicate, must not be null
Parameters:
  transformer - the transformer for the list, must not be null a transformed list backed by the given list
throws:
  IllegalArgumentException - if the List or Transformer is null

Only objects of the specified type can be added to the list.
Parameters:
  list - the list to limit to a specific type, must not be null
Parameters:
  type - the type of objects which may be added to the list a typed list backed by the specified list

This method uses the implementation in the decorators subpackage.
Parameters:
  list - the list to make unmodifiable, must not be null an unmodifiable list backed by the given list
throws:
  IllegalArgumentException - if the list is null