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/**
 * Copyright (C) 2006-2015 phloc systems
 * http://www.phloc.com
 * office[at]phloc[dot]com
 *
 * 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 com.phloc.commons.collections;

import java.util.AbstractSet;
import java.util.Comparator;
import java.util.Iterator;
import java.util.SortedSet;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;

import com.phloc.commons.collections.iterate.EmptyIterator;
import com.phloc.commons.lang.GenericReflection;

/**
 * Default implementation of an empty sorted set.
 * 
 * @author Philip Helger
 */
public final class EmptySortedSet extends AbstractSet  implements SortedSet 
{
  private static final EmptySortedSet INSTANCE = new EmptySortedSet ();

  private EmptySortedSet ()
  {}

  @Override
  public Iterator  iterator ()
  {
    return EmptyIterator. getInstance ();
  }

  @Override
  public int size ()
  {
    return 0;
  }

  @Override
  public boolean contains (final Object obj)
  {
    return false;
  }

  @Nullable
  public Comparator  comparator ()
  {
    return null;
  }

  public SortedSet  subSet (final Object fromElement, final Object toElement)
  {
    return this;
  }

  public SortedSet  headSet (final Object toElement)
  {
    return this;
  }

  public SortedSet  tailSet (final Object fromElement)
  {
    return this;
  }

  public Object first ()
  {
    return null;
  }

  public Object last ()
  {
    return null;
  }

  // ESCA-JAVA0130:
  // ESCA-JAVA0029:
  // Preserves singleton property
  private Object readResolve ()
  {
    return INSTANCE;
  }

  @Nonnull
  public static  SortedSet  getInstance ()
  {
    return GenericReflection.> uncheckedCast (INSTANCE);
  }
}
    

    

    

            

    

            



    
    






    
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