http://fastutil.di.unimi.it/: fastutil extends the Java Collections Framework by providing type-specific maps, sets, lists and priority queues with a small memory footprint and fast access and insertion; provides also big (64-bit) arrays, sets and lists, and fast, practical I/O classes for binary and text files.
  • Sebastiano Vigna 
/*
	* Copyright (C) 2002-2019 Sebastiano Vigna
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	*     http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/
package it.unimi.dsi.fastutil.shorts;
import java.util.List;
import java.util.Iterator;
import java.util.ListIterator;
import java.util.Collection;
import java.util.NoSuchElementException;

An abstract class providing basic methods for lists implementing a
type-specific list interface.


As an additional bonus, this class implements on top of the list operations a
type-specific stack.

/**
 * An abstract class providing basic methods for lists implementing a
 * type-specific list interface.
 *
 * <p>
 * As an additional bonus, this class implements on top of the list operations a
 * type-specific stack.
 */
public abstract class AbstractShortList extends AbstractShortCollection implements ShortList, ShortStack {
	protected AbstractShortList() {
	}
	
Ensures that the given index is nonnegative and not greater than the list
size.

Params:
  • index – 
           an index.
Throws:
/**
	 * Ensures that the given index is nonnegative and not greater than the list
	 * size.
	 *
	 * @param index
	 *            an index.
	 * @throws IndexOutOfBoundsException
	 *             if the given index is negative or greater than the list size.
	 */
	protected void ensureIndex(final int index) {
		if (index < 0)
			throw new IndexOutOfBoundsException("Index (" + index + ") is negative");
		if (index > size())
			throw new IndexOutOfBoundsException("Index (" + index + ") is greater than list size (" + (size()) + ")");
	}
	
Ensures that the given index is nonnegative and smaller than the list size.

Params:
  • index – 
           an index.
Throws:
/**
	 * Ensures that the given index is nonnegative and smaller than the list size.
	 *
	 * @param index
	 *            an index.
	 * @throws IndexOutOfBoundsException
	 *             if the given index is negative or not smaller than the list size.
	 */
	protected void ensureRestrictedIndex(final int index) {
		if (index < 0)
			throw new IndexOutOfBoundsException("Index (" + index + ") is negative");
		if (index >= size())
			throw new IndexOutOfBoundsException(
					"Index (" + index + ") is greater than or equal to list size (" + (size()) + ")");
	}
	
{@inheritDoc}

 This implementation always throws an UnsupportedOperationException. 
/**
	 * {@inheritDoc}
	 *
	 * <p>
	 * This implementation always throws an {@link UnsupportedOperationException}.
	 */
	@Override
	public void add(final int index, final short k) {
		throw new UnsupportedOperationException();
	}
	
{@inheritDoc}

 This implementation delegates to the type-specific version of List.add(int, Object). 
/**
	 * {@inheritDoc}
	 *
	 * <p>
	 * This implementation delegates to the type-specific version of
	 * {@link List#add(int, Object)}.
	 */
	@Override
	public boolean add(final short k) {
		add(size(), k);
		return true;
	}
	
{@inheritDoc}

 This implementation always throws an UnsupportedOperationException. 
/**
	 * {@inheritDoc}
	 *
	 * <p>
	 * This implementation always throws an {@link UnsupportedOperationException}.
	 */
	@Override
	public short removeShort(final int i) {
		throw new UnsupportedOperationException();
	}
	
{@inheritDoc}

 This implementation always throws an UnsupportedOperationException. 
/**
	 * {@inheritDoc}
	 *
	 * <p>
	 * This implementation always throws an {@link UnsupportedOperationException}.
	 */
	@Override
	public short set(final int index, final short k) {
		throw new UnsupportedOperationException();
	}
	
Adds all of the elements in the specified collection to this list (optional
operation).

/**
	 * Adds all of the elements in the specified collection to this list (optional
	 * operation).
	 */
	@Override
	public boolean addAll(int index, final Collection<? extends Short> c) {
		ensureIndex(index);
		final Iterator<? extends Short> i = c.iterator();
		final boolean retVal = i.hasNext();
		while (i.hasNext())
			add(index++, (i.next()).shortValue());
		return retVal;
	}
	
{@inheritDoc}

 This implementation delegates to the type-specific version of List.addAll(int, Collection). 
/**
	 * {@inheritDoc}
	 *
	 * <p>
	 * This implementation delegates to the type-specific version of
	 * {@link List#addAll(int, Collection)}.
	 */
	@Override
	public boolean addAll(final Collection<? extends Short> c) {
		return addAll(size(), c);
	}
	
{@inheritDoc}

 This implementation delegates to listIterator(). 
/**
	 * {@inheritDoc}
	 *
	 * <p>
	 * This implementation delegates to {@link #listIterator()}.
	 */
	@Override
	public ShortListIterator iterator() {
		return listIterator();
	}
	
{@inheritDoc}

 This implementation delegates to listIterator(0). 
/**
	 * {@inheritDoc}
	 *
	 * <p>
	 * This implementation delegates to {@link #listIterator(int) listIterator(0)}.
	 */
	@Override
	public ShortListIterator listIterator() {
		return listIterator(0);
	}
	
{@inheritDoc}


This implementation is based on the random-access methods.

/**
	 * {@inheritDoc}
	 * <p>
	 * This implementation is based on the random-access methods.
	 */
	@Override
	public ShortListIterator listIterator(final int index) {
		ensureIndex(index);
		return new ShortListIterator() {
			int pos = index, last = -1;
			@Override
			public boolean hasNext() {
				return pos < AbstractShortList.this.size();
			}
			@Override
			public boolean hasPrevious() {
				return pos > 0;
			}
			@Override
			public short nextShort() {
				if (!hasNext())
					throw new NoSuchElementException();
				return AbstractShortList.this.getShort(last = pos++);
			}
			@Override
			public short previousShort() {
				if (!hasPrevious())
					throw new NoSuchElementException();
				return AbstractShortList.this.getShort(last = --pos);
			}
			@Override
			public int nextIndex() {
				return pos;
			}
			@Override
			public int previousIndex() {
				return pos - 1;
			}
			@Override
			public void add(final short k) {
				AbstractShortList.this.add(pos++, k);
				last = -1;
			}
			@Override
			public void set(final short k) {
				if (last == -1)
					throw new IllegalStateException();
				AbstractShortList.this.set(last, k);
			}
			@Override
			public void remove() {
				if (last == -1)
					throw new IllegalStateException();
				AbstractShortList.this.removeShort(last);
				/*
				 * If the last operation was a next(), we are removing an element *before* us,
				 * and we must decrease pos correspondingly.
				 */
				if (last < pos)
					pos--;
				last = -1;
			}
		};
	}
	
Returns true if this list contains the specified element.

 This implementation delegates to indexOf(). 
See Also:
/**
	 * Returns true if this list contains the specified element.
	 * <p>
	 * This implementation delegates to {@code indexOf()}.
	 * 
	 * @see List#contains(Object)
	 */
	@Override
	public boolean contains(final short k) {
		return indexOf(k) >= 0;
	}
	@Override
	public int indexOf(final short k) {
		final ShortListIterator i = listIterator();
		short e;
		while (i.hasNext()) {
			e = i.nextShort();
			if (((k) == (e)))
				return i.previousIndex();
		}
		return -1;
	}
	@Override
	public int lastIndexOf(final short k) {
		ShortListIterator i = listIterator(size());
		short e;
		while (i.hasPrevious()) {
			e = i.previousShort();
			if (((k) == (e)))
				return i.nextIndex();
		}
		return -1;
	}
	@Override
	public void size(final int size) {
		int i = size();
		if (size > i)
			while (i++ < size)
				add(((short) 0));
		else
			while (i-- != size)
				removeShort(i);
	}
	@Override
	public ShortList subList(final int from, final int to) {
		ensureIndex(from);
		ensureIndex(to);
		if (from > to)
			throw new IndexOutOfBoundsException("Start index (" + from + ") is greater than end index (" + to + ")");
		return new ShortSubList(this, from, to);
	}
	
{@inheritDoc}


This is a trivial iterator-based implementation. It is expected that
implementations will override this method with a more optimized version.

/**
	 * {@inheritDoc}
	 *
	 * <p>
	 * This is a trivial iterator-based implementation. It is expected that
	 * implementations will override this method with a more optimized version.
	 */
	@Override
	public void removeElements(final int from, final int to) {
		ensureIndex(to);
		ShortListIterator i = listIterator(from);
		int n = to - from;
		if (n < 0)
			throw new IllegalArgumentException("Start index (" + from + ") is greater than end index (" + to + ")");
		while (n-- != 0) {
			i.nextShort();
			i.remove();
		}
	}
	
{@inheritDoc}


This is a trivial iterator-based implementation. It is expected that
implementations will override this method with a more optimized version.

/**
	 * {@inheritDoc}
	 *
	 * <p>
	 * This is a trivial iterator-based implementation. It is expected that
	 * implementations will override this method with a more optimized version.
	 */
	@Override
	public void addElements(int index, final short a[], int offset, int length) {
		ensureIndex(index);
		if (offset < 0)
			throw new ArrayIndexOutOfBoundsException("Offset (" + offset + ") is negative");
		if (offset + length > a.length)
			throw new ArrayIndexOutOfBoundsException(
					"End index (" + (offset + length) + ") is greater than array length (" + a.length + ")");
		while (length-- != 0)
			add(index++, a[offset++]);
	}
	
{@inheritDoc}


This implementation delegates to the analogous method for array fragments.

/**
	 * {@inheritDoc}
	 *
	 * <p>
	 * This implementation delegates to the analogous method for array fragments.
	 */
	@Override
	public void addElements(final int index, final short a[]) {
		addElements(index, a, 0, a.length);
	}
	
{@inheritDoc}


This is a trivial iterator-based implementation. It is expected that
implementations will override this method with a more optimized version.

/**
	 * {@inheritDoc}
	 *
	 * <p>
	 * This is a trivial iterator-based implementation. It is expected that
	 * implementations will override this method with a more optimized version.
	 */
	@Override
	public void getElements(final int from, final short a[], int offset, int length) {
		ShortListIterator i = listIterator(from);
		if (offset < 0)
			throw new ArrayIndexOutOfBoundsException("Offset (" + offset + ") is negative");
		if (offset + length > a.length)
			throw new ArrayIndexOutOfBoundsException(
					"End index (" + (offset + length) + ") is greater than array length (" + a.length + ")");
		if (from + length > size())
			throw new IndexOutOfBoundsException(
					"End index (" + (from + length) + ") is greater than list size (" + size() + ")");
		while (length-- != 0)
			a[offset++] = i.nextShort();
	}
	
{@inheritDoc}

 This implementation delegates to removeElements(int, int). 
/**
	 * {@inheritDoc}
	 * <p>
	 * This implementation delegates to {@link #removeElements(int, int)}.
	 */
	@Override
	public void clear() {
		removeElements(0, size());
	}
	private boolean valEquals(final Object a, final Object b) {
		return a == null ? b == null : a.equals(b);
	}
	
Returns the hash code for this list, which is identical to List.hashCode(). 
Returns:the hash code for this list.
/**
	 * Returns the hash code for this list, which is identical to
	 * {@link java.util.List#hashCode()}.
	 *
	 * @return the hash code for this list.
	 */
	@Override
	public int hashCode() {
		ShortIterator i = iterator();
		int h = 1, s = size();
		while (s-- != 0) {
			short k = i.nextShort();
			h = 31 * h + (k);
		}
		return h;
	}
	@Override
	public boolean equals(final Object o) {
		if (o == this)
			return true;
		if (!(o instanceof List))
			return false;
		final List<?> l = (List<?>) o;
		int s = size();
		if (s != l.size())
			return false;
		if (l instanceof ShortList) {
			final ShortListIterator i1 = listIterator(), i2 = ((ShortList) l).listIterator();
			while (s-- != 0)
				if (i1.nextShort() != i2.nextShort())
					return false;
			return true;
		}
		final ListIterator<?> i1 = listIterator(), i2 = l.listIterator();
		while (s-- != 0)
			if (!valEquals(i1.next(), i2.next()))
				return false;
		return true;
	}
	
Compares this list to another object. If the argument is a List, this method performs a lexicographical comparison; otherwise, it throws a ClassCastException. 
Params:
  • l – 
           a list.
Throws:
Returns:if the argument is a List, a negative integer, zero, or a positive integer as this list is lexicographically less than, equal to, or greater than the argument.
/**
	 * Compares this list to another object. If the argument is a
	 * {@link java.util.List}, this method performs a lexicographical comparison;
	 * otherwise, it throws a {@code ClassCastException}.
	 *
	 * @param l
	 *            a list.
	 * @return if the argument is a {@link java.util.List}, a negative integer,
	 *         zero, or a positive integer as this list is lexicographically less
	 *         than, equal to, or greater than the argument.
	 * @throws ClassCastException
	 *             if the argument is not a list.
	 */

	@Override
	public int compareTo(final List<? extends Short> l) {
		if (l == this)
			return 0;
		if (l instanceof ShortList) {
			final ShortListIterator i1 = listIterator(), i2 = ((ShortList) l).listIterator();
			int r;
			short e1, e2;
			while (i1.hasNext() && i2.hasNext()) {
				e1 = i1.nextShort();
				e2 = i2.nextShort();
				if ((r = (Short.compare((e1), (e2)))) != 0)
					return r;
			}
			return i2.hasNext() ? -1 : (i1.hasNext() ? 1 : 0);
		}
		ListIterator<? extends Short> i1 = listIterator(), i2 = l.listIterator();
		int r;
		while (i1.hasNext() && i2.hasNext()) {
			if ((r = ((Comparable<? super Short>) i1.next()).compareTo(i2.next())) != 0)
				return r;
		}
		return i2.hasNext() ? -1 : (i1.hasNext() ? 1 : 0);
	}
	@Override
	public void push(final short o) {
		add(o);
	}
	@Override
	public short popShort() {
		if (isEmpty())
			throw new NoSuchElementException();
		return removeShort(size() - 1);
	}
	@Override
	public short topShort() {
		if (isEmpty())
			throw new NoSuchElementException();
		return getShort(size() - 1);
	}
	@Override
	public short peekShort(final int i) {
		return getShort(size() - 1 - i);
	}
	
Removes a single instance of the specified element from this collection, if
it is present (optional operation).

 This implementation delegates to indexOf(). 
See Also:
/**
	 * Removes a single instance of the specified element from this collection, if
	 * it is present (optional operation).
	 * <p>
	 * This implementation delegates to {@code indexOf()}.
	 * 
	 * @see List#remove(Object)
	 */
	@Override
	public boolean rem(final short k) {
		int index = indexOf(k);
		if (index == -1)
			return false;
		removeShort(index);
		return true;
	}
	@Override
	public boolean addAll(int index, final ShortCollection c) {
		ensureIndex(index);
		final ShortIterator i = c.iterator();
		final boolean retVal = i.hasNext();
		while (i.hasNext())
			add(index++, i.nextShort());
		return retVal;
	}
	
{@inheritDoc}

 This implementation delegates to the type-specific version of List.addAll(int, Collection). 
/**
	 * {@inheritDoc}
	 *
	 * <p>
	 * This implementation delegates to the type-specific version of
	 * {@link List#addAll(int, Collection)}.
	 */
	@Override
	public boolean addAll(final int index, final ShortList l) {
		return addAll(index, (ShortCollection) l);
	}
	
{@inheritDoc}

 This implementation delegates to the type-specific version of List.addAll(int, Collection). 
/**
	 * {@inheritDoc}
	 *
	 * <p>
	 * This implementation delegates to the type-specific version of
	 * {@link List#addAll(int, Collection)}.
	 */
	@Override
	public boolean addAll(final ShortCollection c) {
		return addAll(size(), c);
	}
	
{@inheritDoc}

 This implementation delegates to the type-specific list version of List.addAll(int, Collection). 
/**
	 * {@inheritDoc}
	 *
	 * <p>
	 * This implementation delegates to the type-specific list version of
	 * {@link List#addAll(int, Collection)}.
	 */
	@Override
	public boolean addAll(final ShortList l) {
		return addAll(size(), l);
	}
	@Override
	public String toString() {
		final StringBuilder s = new StringBuilder();
		final ShortIterator i = iterator();
		int n = size();
		short k;
		boolean first = true;
		s.append("[");
		while (n-- != 0) {
			if (first)
				first = false;
			else
				s.append(", ");
			k = i.nextShort();
			s.append(String.valueOf(k));
		}
		s.append("]");
		return s.toString();
	}
	
A class implementing a sublist view. 
/** A class implementing a sublist view. */
	public static class ShortSubList extends AbstractShortList implements java.io.Serializable {
		private static final long serialVersionUID = -7046029254386353129L;
		
The list this sublist restricts. 
/** The list this sublist restricts. */
		protected final ShortList l;
		
Initial (inclusive) index of this sublist. 
/** Initial (inclusive) index of this sublist. */
		protected final int from;
		
Final (exclusive) index of this sublist. 
/** Final (exclusive) index of this sublist. */
		protected int to;
		public ShortSubList(final ShortList l, final int from, final int to) {
			this.l = l;
			this.from = from;
			this.to = to;
		}
		private boolean assertRange() {
			assert from <= l.size();
			assert to <= l.size();
			assert to >= from;
			return true;
		}
		@Override
		public boolean add(final short k) {
			l.add(to, k);
			to++;
			assert assertRange();
			return true;
		}
		@Override
		public void add(final int index, final short k) {
			ensureIndex(index);
			l.add(from + index, k);
			to++;
			assert assertRange();
		}
		@Override
		public boolean addAll(final int index, final Collection<? extends Short> c) {
			ensureIndex(index);
			to += c.size();
			return l.addAll(from + index, c);
		}
		@Override
		public short getShort(final int index) {
			ensureRestrictedIndex(index);
			return l.getShort(from + index);
		}
		@Override
		public short removeShort(final int index) {
			ensureRestrictedIndex(index);
			to--;
			return l.removeShort(from + index);
		}
		@Override
		public short set(final int index, final short k) {
			ensureRestrictedIndex(index);
			return l.set(from + index, k);
		}
		@Override
		public int size() {
			return to - from;
		}
		@Override
		public void getElements(final int from, final short[] a, final int offset, final int length) {
			ensureIndex(from);
			if (from + length > size())
				throw new IndexOutOfBoundsException(
						"End index (" + from + length + ") is greater than list size (" + size() + ")");
			l.getElements(this.from + from, a, offset, length);
		}
		@Override
		public void removeElements(final int from, final int to) {
			ensureIndex(from);
			ensureIndex(to);
			l.removeElements(this.from + from, this.from + to);
			this.to -= (to - from);
			assert assertRange();
		}
		@Override
		public void addElements(int index, final short a[], int offset, int length) {
			ensureIndex(index);
			l.addElements(this.from + index, a, offset, length);
			this.to += length;
			assert assertRange();
		}
		@Override
		public ShortListIterator listIterator(final int index) {
			ensureIndex(index);
			return new ShortListIterator() {
				int pos = index, last = -1;
				@Override
				public boolean hasNext() {
					return pos < size();
				}
				@Override
				public boolean hasPrevious() {
					return pos > 0;
				}
				@Override
				public short nextShort() {
					if (!hasNext())
						throw new NoSuchElementException();
					return l.getShort(from + (last = pos++));
				}
				@Override
				public short previousShort() {
					if (!hasPrevious())
						throw new NoSuchElementException();
					return l.getShort(from + (last = --pos));
				}
				@Override
				public int nextIndex() {
					return pos;
				}
				@Override
				public int previousIndex() {
					return pos - 1;
				}
				@Override
				public void add(short k) {
					if (last == -1)
						throw new IllegalStateException();
					ShortSubList.this.add(pos++, k);
					last = -1;
					assert assertRange();
				}
				@Override
				public void set(short k) {
					if (last == -1)
						throw new IllegalStateException();
					ShortSubList.this.set(last, k);
				}
				@Override
				public void remove() {
					if (last == -1)
						throw new IllegalStateException();
					ShortSubList.this.removeShort(last);
					/*
					 * If the last operation was a next(), we are removing an element *before* us,
					 * and we must decrease pos correspondingly.
					 */
					if (last < pos)
						pos--;
					last = -1;
					assert assertRange();
				}
			};
		}
		@Override
		public ShortList subList(final int from, final int to) {
			ensureIndex(from);
			ensureIndex(to);
			if (from > to)
				throw new IllegalArgumentException("Start index (" + from + ") is greater than end index (" + to + ")");
			return new ShortSubList(this, from, to);
		}
		@Override
		public boolean rem(final short k) {
			int index = indexOf(k);
			if (index == -1)
				return false;
			to--;
			l.removeShort(from + index);
			assert assertRange();
			return true;
		}
		@Override
		public boolean addAll(final int index, final ShortCollection c) {
			ensureIndex(index);
			return super.addAll(index, c);
		}
		@Override
		public boolean addAll(final int index, final ShortList l) {
			ensureIndex(index);
			return super.addAll(index, l);
		}
	}
}