Interface Map<K,V>
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- All Known Implementing Classes:
- AbstractHashMap, AbstractMap, AbstractSortedMap, ChainHashMap, ProbeHashMap, SortedTableMap, TreeMap, UnsortedTableMap
public interface Map<K,V>
An interface for an associative collecction, i.e., a map, that contains key/value entries.
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method and Description java.lang.Iterable<Entry<K,V>>
entrySet()
Returns an iterable collection of all key-value entries of the map.V
get(K key)
Returns the value associated with the specified key, or null if no such entry exists.boolean
isEmpty()
Tests whether the map is empty.V
put(K key, V value)
Associates the given value with the given key.V
remove(K key)
Removes the entry with the specified key, if present, and returns its associated value.int
size()
Returns the number of entries in the map.
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Method Detail
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size
int size()
Returns the number of entries in the map.- Returns:
- number of entries in the map
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isEmpty
boolean isEmpty()
Tests whether the map is empty.- Returns:
- true if the map is empty, false otherwise
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get
V get(K key)
Returns the value associated with the specified key, or null if no such entry exists.- Parameters:
key
- the key whose associated value is to be returned- Returns:
- the associated value, or null if no such entry exists
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put
V put(K key, V value)
Associates the given value with the given key. If an entry with the key was already in the map, this replaces the previous value with the new one and returns the old value. Otherwise, a new entry is added and null is returned.- Parameters:
key
- key with which the specified value is to be associatedvalue
- value to be associated with the specified key- Returns:
- the previous value associated with the key (or null, if no such i entry)
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remove
V remove(K key)
Removes the entry with the specified key, if present, and returns its associated value. Otherwise does nothing and returns null.- Parameters:
key
- the key whose entry is to be removed from the map- Returns:
- the previous value associated with the removed key, or null if no such entry exists
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