BiMap.java

package com.vitco.util.misc;

import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

/**
 * Bidirection HashMap
 */
public class BiMap<KeyType, ValueType>{
    private final Map<KeyType, ValueType> keyToValueMap = new ConcurrentHashMap<KeyType, ValueType>();
    private final Map<ValueType, KeyType> valueToKeyMap = new ConcurrentHashMap<ValueType, KeyType>();

    synchronized public Set<KeyType> keySet() {
        return keyToValueMap.keySet();
    }

    synchronized public void put(KeyType key, ValueType value){
        keyToValueMap.put(key, value);
        valueToKeyMap.put(value, key);
    }

    synchronized public ValueType removeByKey(KeyType key){
        ValueType removedValue = keyToValueMap.remove(key);
        valueToKeyMap.remove(removedValue);
        return removedValue;
    }

    synchronized public KeyType removeByValue(ValueType value){
        KeyType removedKey = valueToKeyMap.remove(value);
        keyToValueMap.remove(removedKey);
        return removedKey;
    }

    synchronized public void clear() {
        keyToValueMap.clear();
        valueToKeyMap.clear();
    }

    public boolean containsKey(KeyType key){
        return keyToValueMap.containsKey(key);
    }

    public boolean containsValue(ValueType value){
        return keyToValueMap.containsValue(value);
    }

    public KeyType getKey(ValueType value){
        return valueToKeyMap.get(value);
    }

    public ValueType get(KeyType key){
        return keyToValueMap.get(key);
    }

    // retrieve the amount of entries
    public int size() {
        return keyToValueMap.size();
    }
}