programming-examples/java/Collection_API_Problems/Java Program to Implement EnumMap API.java

import java.util.Collection;
import java.util.EnumMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

public class EnumMapImpl<K extends Enum<K>, V>
{
    private EnumMap<K, V> enumMap;

    /** Creates an empty enum map with the specified key type. **/
    public EnumMapImpl(Class<K> keyType)
    {
        enumMap = new EnumMap<K, V>(keyType);
    }

    /**
     * Creates an enum map with the same key type as the specified enum map,
     * initially containing the same mappings (if any).
     **/
    public EnumMapImpl(EnumMap<K, ? extends V> m)
    {
        enumMap = new EnumMap<K, V>(m);
    }

    /** Creates an enum map initialized from the specified map. **/
    public EnumMapImpl(Map<K, ? extends V> m)
    {
        enumMap = new EnumMap<K, V>(m);
    }

    /** Removes all of the mappings from this map. **/
    public void clear()
    {
        enumMap.clear();
    }

    /** Returns true if this map contains a mapping for the specified key. **/
    public boolean containsKey(Object key)
    {
        return enumMap.containsKey(key);
    }

    /** Returns true if this map maps one or more keys to the specified value. **/
    public boolean containsValue(Object value)
    {
        return enumMap.containsValue(value);
    }

    /** Returns a Set view of the mappings contained in this map. **/
    public Set<Map.Entry<K, V>> entrySet()
    {
        return enumMap.entrySet();
    }

    /** Returns a Set view of the keys contained in this map. **/
    public Set<K> keySet()
    {
        return enumMap.keySet();
    }

    /**
     * Returns the value to which the specified key is mapped, or null if this
     * map contains no mapping for the key.
     **/
    public V get(Object key)
    {
        return enumMap.get(key);
    }

    /** Associates the specified value with the specified key in this map. **/
    public V put(K key, V value)
    {
        return enumMap.put(key, value);
    }

    /** Copies all of the mappings from the specified map to this map. **/
    public void putAll(Map<? extends K, ? extends V> map)
    {
        enumMap.putAll(map);
    }

    /** Removes the mapping for this key from this TreeMap if present. **/
    public V remove(Object key)
    {
        return enumMap.remove(key);
    }

    /** Returns the number of key-value mappings in this map. **/
    public int size()
    {
        return enumMap.size();
    }

    /** Returns a Collection view of the values contained in this map. **/
    public Collection<V> values()
    {
        return enumMap.values();
    }

    /** Returns true if this map contains no key-value mappings. **/
    public boolean isEmpty()
    {
        return enumMap.isEmpty();
    }

    public enum NUMBER
    {
        FIRST, SECOND, THIRD, FOURTH;
    }

    public static void main(String... arg)
    {
        EnumMapImpl<NUMBER, Integer> enumMap = new EnumMapImpl<NUMBER, Integer>(NUMBER.class);
        enumMap.put(NUMBER.FIRST, 100);
        enumMap.put(NUMBER.SECOND, 200);
        enumMap.put(NUMBER.THIRD, 300);
        System.out.println("the key set of the enumMap is ");
        Set<NUMBER> keySet = enumMap.keySet();
        Iterator<NUMBER> itr = keySet.iterator();
        while (itr.hasNext())
            {
                System.out.print(itr.next() + "\t");
            }
        System.out.println();
        System.out.println("the values of the enumMap is ");
        Collection<Integer> collectionValues = enumMap.values();
        Iterator<Integer> itr2 = collectionValues.iterator();
        while (itr2.hasNext())
            {
                System.out.print(itr2.next() + "\t");
            }
        System.out.println();
        System.out.println("the entry set of the enumMap is ");
        Iterator<Entry<NUMBER, Integer>> eitr;
        Set<Entry<NUMBER, Integer>> entrySet = enumMap.entrySet();
        eitr = entrySet.iterator();
        while (eitr.hasNext())
            {
                System.out.println(eitr.next() + "\t");
            }
        System.out.println("the enumMap contains Key THIRD :" + enumMap.containsKey(NUMBER.THIRD));
        System.out.println("the enumMap contains Value 600 :" + enumMap.containsValue(600));
        System.out.println("the size of the enumMap is " + enumMap.size());
        enumMap.clear();
        if (enumMap.isEmpty())
            System.out.println("the enumMap is empty");
        else
            System.out.println("the enumMap is not empty");
    }
}

/*
the key set of the enumMap is
FIRST   SECOND  THIRD
the values of the enumMap is
100 200 300
the entry set of the enumMap is
FIRST=100
SECOND=200
THIRD=300
the enumMap contains Key THIRD :true
the enumMap contains Value 600 :false
the size of the enumMap is 3
the enumMap is empty