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Posted to issues@commons.apache.org by "offbynull (JIRA)" <ji...@apache.org> on 2012/12/28 07:22:12 UTC
[jira] [Created] (LANG-864) Collection wrappers to for unmodifiable
/ null-safe collections
offbynull created LANG-864:
------------------------------
Summary: Collection wrappers to for unmodifiable / null-safe collections
Key: LANG-864
URL: https://issues.apache.org/jira/browse/LANG-864
Project: Commons Lang
Issue Type: New Feature
Reporter: offbynull
Priority: Minor
Would it be possible to add something like this to commons lang? Commons collection looks like it's pretty much dead, and the only alternative for this kind of stuff is Google's horribly designed and massively confusing Guava library.
Below are a couple of quick and dirty (untested) examples of the kind of wrappers I'm talking about. Note the isLocked/locked methods and the viewBlacklist method. Using these methods, it's easy for a component receiving a list/set to identify that it's currently unmodifiable and that the collection restricts certain values (e.g. null? maybe others?).
{code}
public final class LockableBlacklistableList<T> implements List<T> {
private boolean locked;
private List<T> list;
private Set<T> blacklist;
public LockableBlacklistableList(List<T> backingList, T... blacklist) {
if (backingList == null) {
throw new NullPointerException();
}
if (!backingList.isEmpty()) {
throw new IllegalArgumentException();
}
this.blacklist = new HashSet<>(Arrays.asList(blacklist));
this.list = backingList;
}
public void lock() {
locked = true;
}
public boolean isLocked() {
return locked;
}
public Set<T> viewBlacklist() {
return Collections.unmodifiableSet(blacklist);
}
@Override
public int size() {
return list.size();
}
@Override
public boolean isEmpty() {
return list.isEmpty();
}
@Override
public boolean contains(Object o) {
return list.contains(o);
}
@Override
public Iterator<T> iterator() {
final Iterator<T> it = list.iterator();
return new Iterator<T>() {
@Override
public boolean hasNext() {
return it.hasNext();
}
@Override
public T next() {
return it.next();
}
@Override
public void remove() {
if (locked) {
throw new IllegalStateException();
}
it.remove();
}
};
}
@Override
public Object[] toArray() {
return list.toArray();
}
@Override
public <T> T[] toArray(T[] a) {
return list.toArray(a);
}
@Override
public boolean add(T e) {
if (locked) {
throw new IllegalStateException();
}
return list.add(e);
}
@Override
public boolean remove(Object o) {
if (locked) {
throw new IllegalStateException();
}
return list.remove(o);
}
@Override
public boolean containsAll(Collection<?> c) {
return list.containsAll(c);
}
@Override
public boolean addAll(Collection<? extends T> c) {
if (locked) {
throw new IllegalStateException();
}
for (T item : c) {
if (blacklist.contains(item)) {
throw new IllegalArgumentException();
}
}
return list.addAll(c);
}
@Override
public boolean addAll(int index, Collection<? extends T> c) {
if (locked) {
throw new IllegalStateException();
}
for (T item : c) {
if (blacklist.contains(item)) {
throw new IllegalArgumentException();
}
}
return list.addAll(index, c);
}
@Override
public boolean removeAll(Collection<?> c) {
if (locked) {
throw new IllegalStateException();
}
return list.removeAll(c);
}
@Override
public boolean retainAll(Collection<?> c) {
if (locked) {
throw new IllegalStateException();
}
return list.retainAll(c);
}
@Override
public void clear() {
if (locked) {
throw new IllegalStateException();
}
list.clear();
}
@Override
public boolean equals(Object o) {
return list.equals(o);
}
@Override
public int hashCode() {
return list.hashCode();
}
@Override
public T get(int index) {
return list.get(index);
}
@Override
public T set(int index, T element) {
if (locked) {
throw new IllegalStateException();
}
if (blacklist.contains(element)) {
throw new IllegalArgumentException();
}
return list.set(index, element);
}
@Override
public void add(int index, T element) {
if (locked) {
throw new IllegalStateException();
}
if (blacklist.contains(element)) {
throw new IllegalArgumentException();
}
list.add(index, element);
}
@Override
public T remove(int index) {
if (locked) {
throw new IllegalStateException();
}
return list.remove(index);
}
@Override
public int indexOf(Object o) {
return list.indexOf(o);
}
@Override
public int lastIndexOf(Object o) {
return list.lastIndexOf(o);
}
@Override
public ListIterator<T> listIterator() {
final ListIterator<T> backingListIt = list.listIterator();
return new ListIterator<T>() {
@Override
public boolean hasNext() {
return backingListIt.hasNext();
}
@Override
public T next() {
return backingListIt.next();
}
@Override
public boolean hasPrevious() {
return backingListIt.hasPrevious();
}
@Override
public T previous() {
return backingListIt.previous();
}
@Override
public int nextIndex() {
return backingListIt.nextIndex();
}
@Override
public int previousIndex() {
return backingListIt.previousIndex();
}
@Override
public void remove() {
if (locked) {
throw new IllegalStateException();
}
backingListIt.remove();
}
@Override
public void set(T e) {
if (locked) {
throw new IllegalStateException();
}
if (blacklist.contains(e)) {
throw new IllegalArgumentException();
}
backingListIt.set(e);
}
@Override
public void add(T e) {
if (locked) {
throw new IllegalStateException();
}
if (blacklist.contains(e)) {
throw new IllegalArgumentException();
}
backingListIt.add(e);
}
};
}
@Override
public ListIterator<T> listIterator(int index) {
final ListIterator<T> backingListIt = list.listIterator(index);
return new ListIterator<T>() {
@Override
public boolean hasNext() {
return backingListIt.hasNext();
}
@Override
public T next() {
return backingListIt.next();
}
@Override
public boolean hasPrevious() {
return backingListIt.hasPrevious();
}
@Override
public T previous() {
return backingListIt.previous();
}
@Override
public int nextIndex() {
return backingListIt.nextIndex();
}
@Override
public int previousIndex() {
return backingListIt.previousIndex();
}
@Override
public void remove() {
if (locked) {
throw new IllegalStateException();
}
backingListIt.remove();
}
@Override
public void set(T e) {
if (locked) {
throw new IllegalStateException();
}
if (blacklist.contains(e)) {
throw new IllegalArgumentException();
}
backingListIt.set(e);
}
@Override
public void add(T e) {
if (locked) {
throw new IllegalStateException();
}
if (blacklist.contains(e)) {
throw new IllegalArgumentException();
}
backingListIt.add(e);
}
};
}
@Override
public List<T> subList(int fromIndex, int toIndex) {
LockableBlacklistableList<T> ret = new LockableBlacklistableList<>(
list.subList(fromIndex, toIndex));
ret.locked = locked;
ret.blacklist = blacklist;
return ret;
}
}
{code}
{code}
public final class LockableBlacklistableSet<T> implements Set<T> {
private boolean locked;
private Set<T> set;
private Set<T> blacklist;
public LockableBlacklistableSet(Set<T> backingSet, T... blacklist) {
if (backingSet == null) {
throw new NullPointerException();
}
if (!backingSet.isEmpty()) {
throw new IllegalArgumentException();
}
this.blacklist = new HashSet<>(Arrays.asList(blacklist));
this.set = backingSet;
}
public void lock() {
locked = true;
}
public boolean isLocked() {
return locked;
}
public Set<T> viewBlacklist() {
return Collections.unmodifiableSet(blacklist);
}
public int size() {
return set.size();
}
public boolean isEmpty() {
return set.isEmpty();
}
public boolean contains(Object o) {
return set.contains(o);
}
public Iterator<T> iterator() {
final Iterator<T> it = set.iterator();
return new Iterator<T>() {
@Override
public boolean hasNext() {
return it.hasNext();
}
@Override
public T next() {
return it.next();
}
@Override
public void remove() {
if (locked) {
throw new IllegalStateException();
}
it.remove();
}
};
}
public Object[] toArray() {
return set.toArray();
}
public <T> T[] toArray(T[] a) {
return set.toArray(a);
}
public boolean add(T e) {
if (locked) {
throw new IllegalStateException();
}
return set.add(e);
}
public boolean remove(Object o) {
if (locked) {
throw new IllegalStateException();
}
return set.remove(o);
}
public boolean containsAll(Collection<?> c) {
return set.containsAll(c);
}
public boolean addAll(Collection<? extends T> c) {
if (locked) {
throw new IllegalStateException();
}
for (T item : c) {
if (blacklist.contains(item)) {
throw new IllegalArgumentException();
}
}
return set.addAll(c);
}
public boolean retainAll(Collection<?> c) {
if (locked) {
throw new IllegalStateException();
}
return set.retainAll(c);
}
public boolean removeAll(Collection<?> c) {
if (locked) {
throw new IllegalStateException();
}
return set.removeAll(c);
}
public void clear() {
if (locked) {
throw new IllegalStateException();
}
set.clear();
}
public boolean equals(Object o) {
return set.equals(o);
}
public int hashCode() {
return set.hashCode();
}
}
{code}
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