我必须将带有 String 键和两个 String 值的文件读入双向哈希图中。如何实现 put() 方法以将键和值添加到哈希图中？
经过数小时的研究，我只发现了一个使用forward和backward的例子。
backward.put(value, key);
return forward.put(key, value)
不幸的是，它只是给了我null。非常感谢任何指导。
这是课程。我不希望你们为我做任务。我只需要帮助实现 put() 方法……仅此而已。我只需要一些正确方向的指导。
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
@SuppressWarnings("serial")
public class TwoWayHashMap<K, V> extends HashMap<K, V>
{
// Declare all the data members and instance variables
// that are required for this class
/**
* Construct an empty two-way hash map.
*/
public TwoWayHashMap()
{
// Provide your definition/implementation of this constructor
}
/**
* Construct a two-way hash map with the given hash map, which must have a
* one-to-one relationship between elements.
*
* @param map The hash map.
*/
public TwoWayHashMap(Map<? extends K, ? extends V> map)
{
// Provide your definition/implementation of this constructor
}
/**
* Construct an empty two-way hash map with an initial capacity.
*
* @param initialCapacity The initial capacity.
*/
public TwoWayHashMap(int initialCapacity)
{
// Provide your definition/implementation of this constructor
}
/**
* Construct an empty two-way hash map with an initial capacity and a load
* factor.
*
* @param initialCapacity The initial capacity.
* @param loadFactor The load factor.
*/
public TwoWayHashMap(int initialCapacity, float loadFactor)
{
// Provide your definition/implementation of this constructor
}
/**
* Clear this two-way hash map.
*/
@Override
public void clear()
{
// Provide your definition/implementation of this method
}
/**
* Clone this two-way hash map and return the clone.
*
* @return The clone.
*/
@Override
public Object clone()
{
// Provide your definition/implementation of this method
}
/**
* Test whether this two-way hash map contains the given value.
*
* @param value The value.
* @return true if the value is contained.
*/
@Override
public boolean containsValue(Object value)
{
// Provide your definition/implementation of this method
}
/**
* Given a value, return the corresponding key in this two-way hash map.
*
* @param value The value.
* @return the key.
*/
public K getKey(Object value)
{
// Provide your definition/implementation of this method
}
/**
* Put a value into this two-way hash map and associate it with a key.
*
* @param key The key.
* @param value The value.
* @return The value previously associated with the key in this two-way
* hash map.
*/
@Override
public V put(K key, V value)
{
// Provide your definition/implementation of this method
}
/**
* Remove the value associated with the given key.
*
* @param key The key.
* @return The removed value, or null if not found.
*/
@Override
public V remove(Object key)
{
// Provide your definition/implementation of this method
}
/**
* Returns the inverse view of this TwoWayHashMap, which maps each
* of this TwoWayHashMap's values to its associated key.
*
* @return the inverse view of this TwoWayHashMap
*/
public HashMap<V, K> inverse()
{
// Provide your definition/implementation of this method
}
/**
* Return a set containing all the values in this two-way hash map.
*
* @return The set.
*/
@Override
public Set<V> values()
{
// Provide your definition/implementation of this method
}
/**
* Return a string representation of this object
*
* @return The string object
*/
@Override
public String toString()
{
// Provide your definition/implementation of this method
}
}