비슷한 문제가있었습니다. 나는 주문한 세트가 필요하지 않았지만 빠른 indexOf/ contains. 거기에서 아무것도 찾지 못했기 때문에 직접 구현했습니다. 다음은 코드입니다. 모든 대량 목록 작업이 버전 만큼 빠르지는 않지만 Set및을 모두 구현합니다 .ListArrayList
면책 조항 : 테스트되지 않음
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Set;
import java.util.Collection;
import java.util.Comparator;
import java.util.function.Predicate;
import java.util.function.UnaryOperator;
import static java.util.Objects.requireNonNull;
/**
* An ArrayList that keeps an index of its content so that contains()/indexOf() are fast. Duplicate entries are
* ignored as most other java Set's do.
*/
public class IndexedArraySet<E> extends ArrayList<E> implements Set<E> {
public IndexedArraySet() { super(); }
public IndexedArraySet(Iterable<E> c) {
super();
addAll(c);
}
private HashMap<E, Integer> indexMap = new HashMap<>();
private void reindex() {
indexMap.clear();
int idx = 0;
for (E item: this) {
addToIndex(item, idx++);
}
}
private E addToIndex(E e, int idx) {
indexMap.putIfAbsent(requireNonNull(e), idx);
return e;
}
@Override
public boolean add(E e) {
if(indexMap.putIfAbsent(requireNonNull(e), size()) != null) return false;
super.add(e);
return true;
}
@Override
public boolean addAll(Collection<? extends E> c) {
return addAll((Iterable<? extends E>) c);
}
public boolean addAll(Iterable<? extends E> c) {
boolean rv = false;
for (E item: c) {
rv |= add(item);
}
return rv;
}
@Override
public boolean contains(Object e) {
return indexMap.containsKey(e);
}
@Override
public int indexOf(Object e) {
if (e == null) return -1;
Integer i = indexMap.get(e);
return (i == null) ? -1 : i;
}
@Override
public int lastIndexOf(Object e) {
return indexOf(e);
}
@Override @SuppressWarnings("unchecked")
public Object clone() {
IndexedArraySet clone = (IndexedArraySet) super.clone();
clone.indexMap = (HashMap) indexMap.clone();
return clone;
}
@Override
public void add(int idx, E e) {
if(indexMap.putIfAbsent(requireNonNull(e), -1) != null) return;
super.add(idx, e);
reindex();
}
@Override
public boolean remove(Object e) {
boolean rv;
try { rv = super.remove(e); }
finally { reindex(); }
return rv;
}
@Override
public void clear() {
super.clear();
indexMap.clear();
}
@Override
public boolean addAll(int idx, Collection<? extends E> c) {
boolean rv;
try {
for(E item : c) {
// check uniqueness
addToIndex(item, -1);
}
rv = super.addAll(idx, c);
} finally {
reindex();
}
return rv;
}
@Override
public boolean removeAll(Collection<?> c) {
boolean rv;
try { rv = super.removeAll(c); }
finally { reindex(); }
return rv;
}
@Override
public boolean retainAll(Collection<?> c) {
boolean rv;
try { rv = super.retainAll(c); }
finally { reindex(); }
return rv;
}
@Override
public boolean removeIf(Predicate<? super E> filter) {
boolean rv;
try { rv = super.removeIf(filter); }
finally { reindex(); }
return rv;
}
@Override
public void replaceAll(final UnaryOperator<E> operator) {
indexMap.clear();
try {
int duplicates = 0;
for (int i = 0; i < size(); i++) {
E newval = requireNonNull(operator.apply(this.get(i)));
if(indexMap.putIfAbsent(newval, i-duplicates) == null) {
super.set(i-duplicates, newval);
} else {
duplicates++;
}
}
removeRange(size()-duplicates, size());
} catch (Exception ex) {
// If there's an exception the indexMap will be inconsistent
reindex();
throw ex;
}
}
@Override
public void sort(Comparator<? super E> c) {
try { super.sort(c); }
finally { reindex(); }
}
}