/*
 * Copyright (c) 2018 Goldman Sachs and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * and Eclipse Distribution License v. 1.0 which accompany this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 */

package org.eclipse.collections.impl.list.fixed;

import java.io.Serializable;
import java.util.Comparator;
import java.util.Iterator;
import java.util.ListIterator;
import java.util.NoSuchElementException;
import java.util.function.UnaryOperator;

import org.eclipse.collections.api.block.function.Function;
import org.eclipse.collections.api.block.function.primitive.BooleanFunction;
import org.eclipse.collections.api.block.function.primitive.ByteFunction;
import org.eclipse.collections.api.block.function.primitive.CharFunction;
import org.eclipse.collections.api.block.function.primitive.DoubleFunction;
import org.eclipse.collections.api.block.function.primitive.FloatFunction;
import org.eclipse.collections.api.block.function.primitive.IntFunction;
import org.eclipse.collections.api.block.function.primitive.LongFunction;
import org.eclipse.collections.api.block.function.primitive.ShortFunction;
import org.eclipse.collections.api.block.procedure.Procedure;
import org.eclipse.collections.api.block.procedure.Procedure2;
import org.eclipse.collections.api.block.procedure.primitive.ObjectIntProcedure;
import org.eclipse.collections.api.factory.Lists;
import org.eclipse.collections.api.list.ImmutableList;
import org.eclipse.collections.api.list.MutableList;
import org.eclipse.collections.api.tuple.Pair;
import org.eclipse.collections.impl.EmptyIterator;

This class is a memory efficient list with no elements. It is created by calling Lists.fixedSize.of() which actually returns a singleton instance.
/** * This class is a memory efficient list with no elements. It is created by calling Lists.fixedSize.of() which * actually returns a singleton instance. */
final class EmptyList<T> extends AbstractMemoryEfficientMutableList<T> implements Serializable { private static final long serialVersionUID = 1L; private Object readResolve() { return Lists.fixedSize.empty(); } @Override public SingletonList<T> with(T value) { return new SingletonList<>(value); } // Weird implementation of clone() is ok on final classes @Override public EmptyList<T> clone() { return this; } @Override public int size() { return 0; } @Override public boolean contains(Object obj) { return false; } @Override public T get(int index) { throw new IndexOutOfBoundsException("Index: " + index + ", Size: " + this.size()); } @Override public T set(int index, T element) { throw new IndexOutOfBoundsException("Index: " + index + ", Size: " + this.size()); }
Since:10.0 - Overridden for efficiency
/** * @since 10.0 - Overridden for efficiency */
@Override public void replaceAll(UnaryOperator<T> operator) { }
Since:10.0 - Overridden for efficiency
/** * @since 10.0 - Overridden for efficiency */
@Override public void sort(Comparator<? super T> comparator) { } @Override public EmptyList<T> sortThis(Comparator<? super T> comparator) { return this; } @Override public <V extends Comparable<? super V>> MutableList<T> sortThisBy(Function<? super T, ? extends V> function) { return this; } @Override public MutableList<T> sortThisByInt(IntFunction<? super T> function) { return this; } @Override public MutableList<T> sortThisByBoolean(BooleanFunction<? super T> function) { return this; } @Override public MutableList<T> sortThisByChar(CharFunction<? super T> function) { return this; } @Override public MutableList<T> sortThisByByte(ByteFunction<? super T> function) { return this; } @Override public MutableList<T> sortThisByShort(ShortFunction<? super T> function) { return this; } @Override public MutableList<T> sortThisByFloat(FloatFunction<? super T> function) { return this; } @Override public MutableList<T> sortThisByLong(LongFunction<? super T> function) { return this; } @Override public MutableList<T> sortThisByDouble(DoubleFunction<? super T> function) { return this; } @Override public T getFirst() { return null; } @Override public T getLast() { return null; } @Override public T getOnly() { throw new IllegalStateException("Size must be 1 but was " + this.size()); } @Override public void each(Procedure<? super T> procedure) { } @Override public void forEachWithIndex(ObjectIntProcedure<? super T> objectIntProcedure) { } @Override public <P> void forEachWith(Procedure2<? super T, ? super P> procedure, P parameter) { } @Override public Iterator<T> iterator() { return EmptyIterator.getInstance(); } @Override public ListIterator<T> listIterator() { return EmptyIterator.getInstance(); } @Override public ListIterator<T> listIterator(int index) { if (index != 0) { throw new IndexOutOfBoundsException("Index: " + index); } return EmptyIterator.getInstance(); } @Override public T min(Comparator<? super T> comparator) { throw new NoSuchElementException(); } @Override public T max(Comparator<? super T> comparator) { throw new NoSuchElementException(); } @Override public T min() { throw new NoSuchElementException(); } @Override public T max() { throw new NoSuchElementException(); } @Override public <V extends Comparable<? super V>> T minBy(Function<? super T, ? extends V> function) { throw new NoSuchElementException(); } @Override public <V extends Comparable<? super V>> T maxBy(Function<? super T, ? extends V> function) { throw new NoSuchElementException(); } @Override public <S> MutableList<Pair<T, S>> zip(Iterable<S> that) { return Lists.fixedSize.empty(); } @Override public MutableList<Pair<T, Integer>> zipWithIndex() { return Lists.fixedSize.empty(); } @Override public ImmutableList<T> toImmutable() { return Lists.immutable.empty(); } }