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A set of some common useful libraries.
package com.github.fmjsjx.libcommon.collection;
import static java.util.Collections.emptyIterator;
import java.util.AbstractSet;
import java.util.Collection;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Objects;
import java.util.Spliterator;
import java.util.Spliterators;
import java.util.function.Consumer;
import java.util.function.Predicate;
import java.util.stream.IntStream;
import java.util.stream.LongStream;
/**
* This class consists exclusively of static methods that operate on or return
* primitive collections ({@link IntSet} or {@link LongSet}).
*
* @see IntSet
* @see IntHashSet
* @see LongSet
* @see LongHashSet
*/
public class PrimitiveCollections {
/**
* Returns an unmodifiable view of the specified set.
*
* @param s the set for which an unmodifiable view is to be returned
* @return an unmodifiable view of the specified set
*/
public static final IntSet unmodifiableSet(IntSet s) {
if (s instanceof UnmodifiableIntSet) {
return s;
}
return new UnmodifiableIntSet(s);
}
/**
* Returns an unmodifiable view of the specified set.
*
* @param s the set for which an unmodifiable view is to be returned
* @return an unmodifiable view of the specified set
*/
public static final LongSet unmodifiableSet(LongSet s) {
if (s instanceof UnmodifiableLongSet) {
return s;
}
return new UnmodifiableLongSet(s);
}
/**
* Returns an empty set.
*
* @return an empty set
*/
public static final IntSet emptyIntSet() {
return EmptyIntSet.INSTANCE;
}
/**
* Returns an empty set.
*
* @return an empty set
*/
public static final LongSet emptyLongSet() {
return EmptyLongSet.INSTANCE;
}
private static final class UnmodifiableIntSet implements IntSet {
private final IntSet s;
private UnmodifiableIntSet(IntSet s) {
this.s = s;
}
@Override
public int size() {
return s.size();
}
@Override
public boolean isEmpty() {
return s.isEmpty();
}
@Override
public boolean contains(Object o) {
return s.contains(o);
}
@Override
public Iterator iterator() {
return new IteratorImpl(s.iterator());
}
@Override
public Object[] toArray() {
return s.toArray();
}
@Override
public T[] toArray(T[] a) {
return s.toArray(a);
}
@Override
public boolean add(Integer e) {
throw new UnsupportedOperationException("add");
}
@Override
public boolean remove(Object o) {
throw new UnsupportedOperationException("remove");
}
@Override
public boolean containsAll(Collection c) {
return s.containsAll(c);
}
@Override
public boolean addAll(Collection c) {
throw new UnsupportedOperationException("addAll");
}
@Override
public boolean retainAll(Collection c) {
throw new UnsupportedOperationException("retainAll");
}
@Override
public boolean removeAll(Collection c) {
throw new UnsupportedOperationException("removeAll");
}
@Override
public void clear() {
throw new UnsupportedOperationException("clear");
}
@Override
public boolean contains(int value) {
return s.contains(value);
}
@Override
public boolean add(int value) {
throw new UnsupportedOperationException("add");
}
@Override
public boolean remove(int value) {
throw new UnsupportedOperationException("remove");
}
@Override
public IntStream intStream() {
return s.intStream();
}
private class IteratorImpl implements Iterator {
final Iterator iter;
private IteratorImpl(Iterator iter) {
this.iter = iter;
}
@Override
public boolean hasNext() {
return iter.hasNext();
}
@Override
public Integer next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
return iter.next();
}
@Override
public void remove() {
throw new UnsupportedOperationException("remove");
}
}
}
private static final class EmptyIntSet extends AbstractSet implements IntSet {
private static final EmptyIntSet INSTANCE = new EmptyIntSet();
public Iterator iterator() {
return emptyIterator();
}
public int size() {
return 0;
}
public boolean isEmpty() {
return true;
}
public void clear() {
}
public boolean contains(Object obj) {
return false;
}
public boolean containsAll(Collection c) {
return c.isEmpty();
}
public Object[] toArray() {
return new Object[0];
}
public T[] toArray(T[] a) {
if (a.length > 0)
a[0] = null;
return a;
}
// Override default methods in Collection
@Override
public void forEach(Consumer action) {
Objects.requireNonNull(action);
}
@Override
public boolean removeIf(Predicate filter) {
Objects.requireNonNull(filter);
return false;
}
@Override
public Spliterator spliterator() {
return Spliterators.emptySpliterator();
}
@Override
public int hashCode() {
return 0;
}
@Override
public boolean contains(int value) {
return false;
}
@Override
public boolean add(int value) {
throw new UnsupportedOperationException("add");
}
@Override
public boolean retainAll(Collection c) {
throw new UnsupportedOperationException("retainAll");
}
@Override
public boolean remove(int value) {
return false;
}
@Override
public IntStream intStream() {
return IntStream.empty();
}
}
private static final class UnmodifiableLongSet implements LongSet {
private final LongSet s;
private UnmodifiableLongSet(LongSet s) {
this.s = s;
}
@Override
public int size() {
return s.size();
}
@Override
public boolean isEmpty() {
return s.isEmpty();
}
@Override
public boolean contains(Object o) {
return s.contains(o);
}
@Override
public Iterator iterator() {
return new IteratorImpl(s.iterator());
}
@Override
public Object[] toArray() {
return s.toArray();
}
@Override
public T[] toArray(T[] a) {
return s.toArray(a);
}
@Override
public boolean add(Long e) {
throw new UnsupportedOperationException("add");
}
@Override
public boolean remove(Object o) {
throw new UnsupportedOperationException("remove");
}
@Override
public boolean containsAll(Collection c) {
return s.containsAll(c);
}
@Override
public boolean addAll(Collection c) {
throw new UnsupportedOperationException("addAll");
}
@Override
public boolean retainAll(Collection c) {
throw new UnsupportedOperationException("retainAll");
}
@Override
public boolean removeAll(Collection c) {
throw new UnsupportedOperationException("removeAll");
}
@Override
public void clear() {
throw new UnsupportedOperationException("clear");
}
@Override
public boolean contains(long value) {
return s.contains(value);
}
@Override
public boolean add(long value) {
throw new UnsupportedOperationException("add");
}
@Override
public boolean remove(long value) {
throw new UnsupportedOperationException("remove");
}
@Override
public LongStream longStream() {
return s.longStream();
}
private class IteratorImpl implements Iterator {
final Iterator iter;
private IteratorImpl(Iterator iter) {
this.iter = iter;
}
@Override
public boolean hasNext() {
return iter.hasNext();
}
@Override
public Long next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
return iter.next();
}
@Override
public void remove() {
throw new UnsupportedOperationException("remove");
}
}
}
private static final class EmptyLongSet extends AbstractSet implements LongSet {
private static final EmptyLongSet INSTANCE = new EmptyLongSet();
public Iterator iterator() {
return emptyIterator();
}
public int size() {
return 0;
}
public boolean isEmpty() {
return true;
}
public void clear() {
}
public boolean contains(Object obj) {
return false;
}
public boolean containsAll(Collection c) {
return c.isEmpty();
}
public Object[] toArray() {
return new Object[0];
}
public T[] toArray(T[] a) {
if (a.length > 0)
a[0] = null;
return a;
}
// Override default methods in Collection
@Override
public void forEach(Consumer action) {
Objects.requireNonNull(action);
}
@Override
public boolean removeIf(Predicate filter) {
Objects.requireNonNull(filter);
return false;
}
@Override
public Spliterator spliterator() {
return Spliterators.emptySpliterator();
}
@Override
public int hashCode() {
return 0;
}
@Override
public boolean contains(long value) {
return false;
}
@Override
public boolean add(long value) {
throw new UnsupportedOperationException("add");
}
@Override
public boolean retainAll(Collection c) {
throw new UnsupportedOperationException("retainAll");
}
@Override
public boolean remove(long value) {
return false;
}
@Override
public LongStream longStream() {
return LongStream.empty();
}
}
private PrimitiveCollections() {
}
}
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