Java example source code file (SafeTreeMap.java)

This example Java source code file (SafeTreeMap.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

classcastexception, comparator, entry, natural_order, navigablemap, navigableset, nullpointerexception, override, safetreemap, sortedmap, suppresswarnings, util

The SafeTreeMap.java Java example source code

/*
 * Copyright (C) 2010 The Guava Authors
 *
 * 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.google.common.collect.testing;

import com.google.common.annotations.GwtIncompatible;

import java.io.Serializable;
import java.util.AbstractSet;
import java.util.Collection;
import java.util.Comparator;
import java.util.Iterator;
import java.util.Map;
import java.util.NavigableMap;
import java.util.NavigableSet;
import java.util.Set;
import java.util.SortedMap;
import java.util.TreeMap;

/**
 * A wrapper around {@code TreeMap} that aggressively checks to see if keys are
 * mutually comparable. This implementation passes the navigable map test
 * suites.
 *
 * @author Louis Wasserman
 */
@GwtIncompatible
public final class SafeTreeMap<K, V> implements Serializable, NavigableMap {
  @SuppressWarnings("unchecked")
  private static final Comparator<Object> NATURAL_ORDER =
      new Comparator<Object>() {
        @Override
        public int compare(Object o1, Object o2) {
          return ((Comparable<Object>) o1).compareTo(o2);
        }
      };

  private final NavigableMap<K, V> delegate;

  public SafeTreeMap() {
    this(new TreeMap<K, V>());
  }

  public SafeTreeMap(Comparator<? super K> comparator) {
    this(new TreeMap<K, V>(comparator));
  }

  public SafeTreeMap(Map<? extends K, ? extends V> map) {
    this(new TreeMap<K, V>(map));
  }

  public SafeTreeMap(SortedMap<K, ? extends V> map) {
    this(new TreeMap<K, V>(map));
  }

  private SafeTreeMap(NavigableMap<K, V> delegate) {
    this.delegate = delegate;
    if (delegate == null) {
      throw new NullPointerException();
    }
    for (K k : keySet()) {
      checkValid(k);
    }
  }

  @Override
  public Entry<K, V> ceilingEntry(K key) {
    return delegate.ceilingEntry(checkValid(key));
  }

  @Override
  public K ceilingKey(K key) {
    return delegate.ceilingKey(checkValid(key));
  }

  @Override
  public void clear() {
    delegate.clear();
  }

  @SuppressWarnings("unchecked")
  @Override
  public Comparator<? super K> comparator() {
    Comparator<? super K> comparator = delegate.comparator();
    if (comparator == null) {
      comparator = (Comparator<? super K>) NATURAL_ORDER;
    }
    return comparator;
  }

  @Override
  public boolean containsKey(Object key) {
    try {
      return delegate.containsKey(checkValid(key));
    } catch (NullPointerException e) {
      return false;
    } catch (ClassCastException e) {
      return false;
    }
  }

  @Override
  public boolean containsValue(Object value) {
    return delegate.containsValue(value);
  }

  @Override
  public NavigableSet<K> descendingKeySet() {
    return delegate.descendingKeySet();
  }

  @Override
  public NavigableMap<K, V> descendingMap() {
    return new SafeTreeMap<K, V>(delegate.descendingMap());
  }

  @Override
  public Set<Entry entrySet() {
    return new AbstractSet<Entry() {
      private Set<Entry delegate() {
        return delegate.entrySet();
      }

      @Override
      public boolean contains(Object object) {
        try {
          return delegate().contains(object);
        } catch (NullPointerException e) {
          return false;
        } catch (ClassCastException e) {
          return false;
        }
      }

      @Override
      public Iterator<Entry iterator() {
        return delegate().iterator();
      }

      @Override
      public int size() {
        return delegate().size();
      }

      @Override
      public boolean remove(Object o) {
        return delegate().remove(o);
      }

      @Override
      public void clear() {
        delegate().clear();
      }
    };
  }

  @Override
  public Entry<K, V> firstEntry() {
    return delegate.firstEntry();
  }

  @Override
  public K firstKey() {
    return delegate.firstKey();
  }

  @Override
  public Entry<K, V> floorEntry(K key) {
    return delegate.floorEntry(checkValid(key));
  }

  @Override
  public K floorKey(K key) {
    return delegate.floorKey(checkValid(key));
  }

  @Override
  public V get(Object key) {
    return delegate.get(checkValid(key));
  }

  @Override
  public SortedMap<K, V> headMap(K toKey) {
    return headMap(toKey, false);
  }

  @Override
  public NavigableMap<K, V> headMap(K toKey, boolean inclusive) {
    return new SafeTreeMap<K, V>(delegate.headMap(checkValid(toKey), inclusive));
  }

  @Override
  public Entry<K, V> higherEntry(K key) {
    return delegate.higherEntry(checkValid(key));
  }

  @Override
  public K higherKey(K key) {
    return delegate.higherKey(checkValid(key));
  }

  @Override
  public boolean isEmpty() {
    return delegate.isEmpty();
  }

  @Override
  public NavigableSet<K> keySet() {
    return navigableKeySet();
  }

  @Override
  public Entry<K, V> lastEntry() {
    return delegate.lastEntry();
  }

  @Override
  public K lastKey() {
    return delegate.lastKey();
  }

  @Override
  public Entry<K, V> lowerEntry(K key) {
    return delegate.lowerEntry(checkValid(key));
  }

  @Override
  public K lowerKey(K key) {
    return delegate.lowerKey(checkValid(key));
  }

  @Override
  public NavigableSet<K> navigableKeySet() {
    return delegate.navigableKeySet();
  }

  @Override
  public Entry<K, V> pollFirstEntry() {
    return delegate.pollFirstEntry();
  }

  @Override
  public Entry<K, V> pollLastEntry() {
    return delegate.pollLastEntry();
  }

  @Override
  public V put(K key, V value) {
    return delegate.put(checkValid(key), value);
  }

  @Override
  public void putAll(Map<? extends K, ? extends V> map) {
    for (K key : map.keySet()) {
      checkValid(key);
    }
    delegate.putAll(map);
  }

  @Override
  public V remove(Object key) {
    return delegate.remove(checkValid(key));
  }

  @Override
  public int size() {
    return delegate.size();
  }

  @Override
  public NavigableMap<K, V> subMap(K fromKey, boolean fromInclusive, K toKey, boolean toInclusive) {
    return new SafeTreeMap<K, V>(
        delegate.subMap(checkValid(fromKey), fromInclusive, checkValid(toKey), toInclusive));
  }

  @Override
  public SortedMap<K, V> subMap(K fromKey, K toKey) {
    return subMap(fromKey, true, toKey, false);
  }

  @Override
  public SortedMap<K, V> tailMap(K fromKey) {
    return tailMap(fromKey, true);
  }

  @Override
  public NavigableMap<K, V> tailMap(K fromKey, boolean inclusive) {
    return new SafeTreeMap<K, V>(delegate.tailMap(checkValid(fromKey), inclusive));
  }

  @Override
  public Collection<V> values() {
    return delegate.values();
  }

  private <T> T checkValid(T t) {
    // a ClassCastException is what's supposed to happen!
    @SuppressWarnings("unchecked")
    K k = (K) t;
    comparator().compare(k, k);
    return t;
  }

  @Override
  public boolean equals(Object obj) {
    return delegate.equals(obj);
  }

  @Override
  public int hashCode() {
    return delegate.hashCode();
  }

  @Override
  public String toString() {
    return delegate.toString();
  }

  private static final long serialVersionUID = 0L;
}