EnumMap is a class which is available in java.util package which provides provides a map implementation for elements of an enum. In EnumMap, enum elements are used as keys.
EnumMap Syntax:
enum Size {
SMALL, MEDIUM, LARGE, EXTRALARGE
}
EnumMap<Size, Integer> sizes = new EnumMap<>(Size.class);
| Method Name | Description |
|---|---|
| put() | inserts the specified key/value mapping to the enumMap. |
| putAll() | inserts all the entries from the specified map to this map. |
| entrySet() | returns a set of all the keys/values mapping (entry) of an enum map. |
| keySet() | returns a set of all the keys of the enum map. |
| values() | returns a set of all the values of the enum map. |
| get() | The get() method returns the value associated with the specified key. It returns null if the specified key is not found. |
| remove(key) | returns and removes the entry associated with the specified key from the map. |
| remove(key, value) | removes the entry from the map only if the specified key mapped to be the specified value and return a boolean value. |
| replace(key, value) | replaces the value associated with the specified key by the new value. |
| replace(key, old, new) | replaces the old value with the new value only if the old value is already associated with the specified key. |
| replaceAll(function) | replaces each value of the map with the result of the specified function. |
| clone() | Creates a copy of the EnumMap. |
| containsKey() | Searches the EnumMap for the specified key and returns a boolean result. |
| containsValue() | Searches the EnumMap for the specified value and returns a boolean result. |
| size() | returns the size of the map. |
| isEmpty() | checks if the map is empty and returns a boolean value. |
import java.util.EnumMap;
class Main {
enum Size {
SMALL, MEDIUM, LARGE, EXTRALARGE
}
public static void main(String[] args) {
// Creating an EnumMap of the Size enum
EnumMap<Size, Integer> sizes1 = new EnumMap<>(Size.class);
// Using the put() Method
sizes1.put(Size.SMALL, 28);
sizes1.put(Size.MEDIUM, 32);
System.out.println("EnumMap1: " + sizes1);
EnumMap<Size, Integer> sizes2 = new EnumMap<>(Size.class);
// Using the putAll() Method
sizes2.putAll(sizes1);
sizes2.put(Size.LARGE, 36);
System.out.println("EnumMap2: " + sizes2);
}
}
import java.util.EnumMap;
class Main {
enum Size {
SMALL, MEDIUM, LARGE, EXTRALARGE
}
public static void main(String[] args) {
// Creating an EnumMap of the Size enum
EnumMap<Size, Integer> sizes = new EnumMap<>(Size.class);
sizes.put(Size.SMALL, 28);
sizes.put(Size.MEDIUM, 32);
sizes.put(Size.LARGE, 36);
sizes.put(Size.EXTRALARGE, 40);
System.out.println("EnumMap: " + sizes);
// Using the entrySet() Method
System.out.println("Key/Value mappings: " + sizes.entrySet());
// Using the keySet() Method
System.out.println("Keys: " + sizes.keySet());
// Using the values() Method
System.out.println("Values: " + sizes.values());
// Using the get() Method
int value = sizes.get(Size.MEDIUM);
System.out.println("Value of MEDIUM: " + value);
}
}
import java.util.EnumMap;
class Main {
enum Size {
SMALL, MEDIUM, LARGE, EXTRALARGE
}
public static void main(String[] args) {
// Creating an EnumMap of the Size enum
EnumMap<Size, Integer> sizes = new EnumMap<>(Size.class);
sizes.put(Size.SMALL, 28);
sizes.put(Size.MEDIUM, 32);
sizes.put(Size.LARGE, 36);
sizes.put(Size.EXTRALARGE, 40);
System.out.println("EnumMap: " + sizes);
// Using the remove() Method
int value = sizes.remove(Size.MEDIUM);
System.out.println("Removed Value: " + value);
boolean result = sizes.remove(Size.SMALL, 28);
System.out.println("Is the entry {SMALL=28} removed? " + result);
System.out.println("Updated EnumMap: " + sizes);
}
}
import java.util.EnumMap;
class Main {
enum Size {
SMALL, MEDIUM, LARGE, EXTRALARGE
}
public static void main(String[] args) {
// Creating an EnumMap of the Size enum
EnumMap<Size, Integer> sizes = new EnumMap<>(Size.class);
sizes.put(Size.SMALL, 28);
sizes.put(Size.MEDIUM, 32);
sizes.put(Size.LARGE, 36);
sizes.put(Size.EXTRALARGE, 40);
System.out.println("EnumMap: " + sizes);
// Using the replace() Method
sizes.replace(Size.MEDIUM, 30);
sizes.replace(Size.LARGE, 36, 34);
System.out.println("EnumMap using replace(): " + sizes);
// Using the replaceAll() Method
sizes.replaceAll((key, oldValue) -> oldValue + 3);
System.out.println("EnumMap using replaceAll(): " + sizes);
}
}
Both the EnumSet and EnumMap class provides data structures to store enum values. However, there exist some major differences between them.