Create a HashMap for counting values in Java

/*  ww  w  . java2s. c  o m*/
//package org.groovymud.utils;

/* Copyright 2008 Matthew Corby-Eaglen
*
* 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. 
*/
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

/**
 * This class wraps a HashMap and provides methods by which key
 * objects can be associated with "counting" values.
 * 
 * useful for timers or other such counting effects
 * 
 * e.g 
 * countingMap.put(object); // puts (object, 0) into the map
 * countingMap.increment(object) // adds 1 to the value of the object (object, 1)
 * countingMap.decrement(object) // decreases the value at the object's key reference by 1 (object, 0)
 * @author matt
 *
 */
public class CountingMap {

  Map<Object, Integer> backingMap = new HashMap<Object, Integer>();

  public void clear() {
    backingMap.clear();
  }

  public boolean containsKey(Object key) {
    return backingMap.containsKey(key);
  }

  public boolean containsValue(Object value) {
    return backingMap.containsValue(value);
  }

  public Set<?> entrySet() {
    return backingMap.entrySet();
  }

  public boolean equals(Object o) {
    return backingMap.equals(o);
  }

  public Integer get(Object key) {
    return backingMap.get(key);
  }

  public int hashCode() {
    return backingMap.hashCode();
  }

  public boolean isEmpty() {
    return backingMap.isEmpty();
  }

  public Set<?> keySet() {
    return backingMap.keySet();
  }

  public Integer remove(Object key) {
    return backingMap.remove(key);
  }

  public int size() {
    return backingMap.size();
  }

  public Collection<Integer> values() {
    return backingMap.values();
  }

  public Integer put(Object key) {
    return put(key, new Integer(0));
  }

  public Integer put(Object key, Integer value) {
    return backingMap.put(key, value);
  }

  public void putAll(Map<Object, Integer> m) {
    backingMap.putAll(m);
  }

  public void increment(Object key) {
    if (!backingMap.containsKey(key)) {
      backingMap.put(key, new Integer(0));
    } else {
      Integer i = backingMap.get(key);
      backingMap.put(key, new Integer(i.intValue() + 1));
    }
  }

  public void decrement(Object key) {
    if (!backingMap.containsKey(key)) {
      backingMap.put(key, new Integer(0));
    } else {
      Integer i = backingMap.get(key);
      backingMap.put(key, new Integer(i.intValue() - 1));
    }
  }

  public Set getKeysAt(int limit) {
    Set ret = new HashSet<Object>();
    for (Object obj : backingMap.keySet()) {
      if (backingMap.get(obj).intValue() == limit) {
        ret.add(obj);
      }
    }
    return ret;
  }

  public Set getKeysAbove(int limit) {
    Set ret = new HashSet<Object>();
    for (Object obj : backingMap.keySet()) {
      if (backingMap.get(obj).intValue() > limit) {
        ret.add(obj);
      }
    }
    return ret;
  }

  public Set getKeysBelow(int limit) {
    Set ret = new HashSet<Object>();
    for (Object obj : backingMap.keySet()) {
      if (backingMap.get(obj).intValue() < limit) {
        ret.add(obj);
      }
    }
    return ret;
  }

}