The Java Map Interface is crucial for managing key-value pairs in Java programming. It allows for efficient data storage, retrieval, and manipulation through various implementations like HashMap, TreeMap, and LinkedHashMap. Each offers unique features such as constant-time performance, key ordering, and entry insertion order maintenance. Understanding these implementations and their methods is essential for effective data management in Java.
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The Java Map Interface is designed for storing unique key-value pairs and allows for efficient operations such as searching and updating
Ordering guarantees
The Map Interface does not guarantee any specific order of entries unless using a SortedMap or LinkedHashMap
Sub-interfaces and implementing classes
The Map Interface has several important sub-interfaces and implementing classes, such as SortedMap and HashMap
Performance characteristics and use cases
Each implementation of the Map Interface has its own performance characteristics and use cases, such as HashMap's efficiency in storing and retrieving elements
The Map Interface can be used to instantiate and populate HashMaps, iterate over their contents, and access and remove elements
SortedMap maintains keys in a sorted order
NavigableMap includes methods for navigating keys
ConcurrentMap is designed for concurrent access
HashMap offers constant-time performance for basic operations
TreeMap organizes entries based on key ordering
LinkedHashMap maintains insertion order
EnumMap
EnumMap is designed for use with enum keys
WeakHashMap
WeakHashMap allows keys to be garbage-collected
IdentityHashMap
IdentityHashMap uses reference equality for comparisons
Hashtable
Hashtable is synchronized and thread-safe
Properties
Properties is a subclass of Hashtable used for maintaining lists of values
The Map.Entry Interface facilitates the manipulation of individual map entries
getKey()
The getKey() method obtains the key of a map entry
getValue()
The getValue() method obtains the value of a map entry
setValue()
The setValue() method replaces the value associated with a key in a map entry
HashMap can be used to instantiate, populate, and iterate over key-value pairs
LinkedHashMap maintains insertion order
TreeMap automatically sorts key-value pairs based on keys' natural ordering or a specified Comparator
get()
The get() method is used to access elements in a map
remove()
The remove() method is used to remove elements from a map
Other methods
The Map Interface also offers methods for clearing the map, checking for specific keys or values, comparing maps, and obtaining collection views of keys, values, or entries
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In a Java Map, keys are unique and can be used to fetch the corresponding ______, with allowances for one ______ key and multiple null values.
value
null
01
Purpose of SortedMap
Maintains keys in sorted order, extends Map interface.
02
Function of NavigableMap
Includes methods to navigate keys, extends SortedMap.
