org.infinispan.commons.util.EmptyIntSet Maven / Gradle / Ivy
package org.infinispan.commons.util;
import java.util.Collection;
import java.util.NoSuchElementException;
import java.util.PrimitiveIterator;
import java.util.Set;
import java.util.stream.IntStream;
/**
* Immutable empty IntSet
* @author wburns
* @since 9.3
*/
class EmptyIntSet extends AbstractImmutableIntSet {
// We just use default hashCode as we only have 1 instance
private final static EmptyIntSet INSTANCE = new EmptyIntSet();
public static IntSet getInstance() {
return INSTANCE;
}
@Override
public boolean contains(int i) {
return false;
}
@Override
public boolean containsAll(IntSet set) {
return set.isEmpty();
}
@Override
public int size() {
return 0;
}
@Override
public boolean isEmpty() {
return true;
}
@Override
public boolean contains(Object o) {
return false;
}
@Override
public PrimitiveIterator.OfInt iterator() {
return EmptyIntIterator.INSTANCE;
}
private static class EmptyIntIterator implements PrimitiveIterator.OfInt {
private static final EmptyIntIterator INSTANCE = new EmptyIntIterator();
@Override
public int nextInt() {
throw new NoSuchElementException();
}
@Override
public boolean hasNext() {
return false;
}
}
@Override
public Object[] toArray() {
return new Object[0];
}
@Override
public T[] toArray(T[] a) {
return a;
}
@Override
public boolean containsAll(Collection c) {
return c.isEmpty();
}
@Override
public IntStream intStream() {
return IntStream.empty();
}
@Override
public byte[] toBitSet() {
return Util.EMPTY_BYTE_ARRAY;
}
@Override
public boolean equals(Object obj) {
if (obj instanceof Set) {
return ((Set) obj).size() == 0;
}
return false;
}
@Override
public String toString() {
return "{}";
}
}