In this article, we will discuss Entry interface (i.e.; Map.Entry) with all its important methods in detail
1. Key points about Map.Entry:
- Entry is the inner interface defined inside Map interface
- It contains important methods to operate on Map entries only
- Map entries is also known as Key-Value pairs
2. Map.Entry interface:
- Entry interface is defined inside Map interface (i.e.; inner interface)
- To access Entry interface, we have to go through Map interface only i.e.; Map.Entry
- Reason: Each Key-Value pair of map is known as Entry. So, to perform Entry specific operations, there should exist Map
- There is no need of Entry interface without existence of Map interface
- It is also referred as collection of entry objects
- Entry interface contains several methods to perform various operation on Map entries
- Present in java.util package inside java.util.Map interface
Source: Team BenchResources.Net
3. Map.Entry interface methods:
| Entry method | Description |
| Object getKey(); | returns key from invoking Map.Entry object |
| Object getValue(); | returns value from invoking Map.Entry object |
| Object setValue(Object val); | set specified value into invoking Map.Entry object |
4. Factors to consider while discussing any collection class
We should consider below factors while discussing any implementation class of collection framework or for that matter Map interface,
- Underlying data structure
- Duplicates are allowed or Not
- Insertion order is maintained or Not
- Whether NULL insertion is possible or Not
- If possible, how many NULL values can be inserted
- Whether collection class provide sorting, by default
- Is there any way to apply customized sorting
- Performance, while dealing with retrieval or manipulation (addition/deletion)
- By default, all methods are synchronized or Not
Related Articles:
- Map interface
- Entry interface
- HashMap class
- LinkedHashMap class
- IdentityHashMap class
- WeakHashMap class
- SortedMap interface
- NavigableMap interface
- TreeMap class
- Hashtable class
- HashMap vs LinkedHashMap
- HashMap v/s LinkedHashMap v/s TreeMap
- HashMap v/s HashSet
- HashMap v/s Hashtable
- Properties class
References:
- https://docs.oracle.com/javase/tutorial/collections/intro/
- https://docs.oracle.com/javase/tutorial/collections/interfaces/collection.html
- https://docs.oracle.com/javase/7/docs/api/java/util/Collection.html
- https://docs.oracle.com/javase/7/docs/api/java/util/Map.html
- https://docs.oracle.com/javase/7/docs/api/java/util/Map.Entry.html
- https://docs.oracle.com/javase/tutorial/collections/interfaces/map.html
Happy Coding !!
Happy Learning !!