java.util.EnumMap class inherits Enum and AbstractMap classes. It’s special type of Map for enum keys.
EnumMap Declaration
public class EnumMap,V> extends AbstractMap implements Serializable, Cloneable
- K: Represent as key in Map of type Enum
- V:Represent as value with respect to K.
Constructors of EnumMap
Constructor |
Description |
EnumMap(Class keyType) |
Create an empty enum map with the given key type. |
EnumMap(EnumMap m) |
Create an enum map with the same key type as the given enum map. |
EnumMap(Map m) |
Create an enum map initialized from the given map. |
Methods of EnumMap
Method |
Description |
clear() |
Clear all the mapping from the map. |
clone() |
Copy the mapped value of one map to another map as sallow cloning. |
containsKey() |
Check whether a given key is present in this map or not. |
containsValue() |
Check whether one or more key is associated with a specified value or not. |
entrySet() |
Create a set of keys/elements contained in the EnumMap. |
equals() |
Compare two maps keys for equality. |
get() |
Get the mapped value with respect to given key. |
hashCode() |
Get the hashcode value of the EnumMap. |
keySet() |
Return the set of the keys contained in the map. |
size() |
Get count of the size of the EnumMap. |
Values() |
Create a collection view of the values contained in this map. |
put() |
Associate the given value with the specified key in this EnumMap. |
putAll() |
Copy all the mappings from one EnumMap to another new EnumMap. |
remove() |
Remove the mapping for the given key from EnumMap if the given key exist in EnumMap. |
EnumMap Example : insert elements and traverse
import java.util.*;
public class EnumMapExample1 {
// create an enum for keys
public enum Days {
Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday
};
public static void main(String[] args) {
// Insert elements in map
EnumMap map = new EnumMap(Days.class);
map.put(Days.Monday, "1");
map.put(Days.Wednesday, "3");
map.put(Days.Friday, "5");
map.put(Days.Sunday, "7");
// traverse map
for (Map.Entry m : map.entrySet()) {
System.out.println(m.getKey() + " " + m.getValue());
}
}
}
Output :
Monday 1
Wednesday 3
Friday 5
Sunday 7
EnumMap Example: insert objects and traverse
import java.util.EnumMap;
import java.util.Map;
class Magzine {
int id;
String name,author,publisher;
int quantity;
public Magzine(int id, String name, String author, String publisher, int quantity) {
this.id = id;
this.name = name;
this.author = author;
this.publisher = publisher;
this.quantity = quantity;
}
}
public class EnumMapWithObjectsExample {
// Creating enum of keys
public enum Key {
One, Two, Three
};
public static void main(String[]args){
EnumMap map = new EnumMap(Key.class);
// Creating Magzines
Magzine m1 = new Magzine(21, "The Sun", "Sy Sunfranchy", "The Sun Company", 8);
Magzine m2 = new Magzine(22, "Glimmer Trains", "Unknown", "Glimmer Train Press", 4);
Magzine m3 = new Magzine(23, "Crazy horse", "Brett Lot", "College of Charleston", 6);
// Adding magzines to Map
map.put(Key.One, m1);
map.put(Key.Two, m2);
map.put(Key.Three, m3);
// Traversing EnumMap
for (Map.Entry entry : map.entrySet()) {
Magzine m = entry.getValue();
System.out.println(m.id + " " + m.name + " " + m.author + " " + m.publisher + " " + m.quantity);
}
}
}
Output :
21 The Sun Sy Sunfranchy The Sun Company 8
22 Glimmer Trains Unknown Glimmer Train Press 4
23 Crazy horse Brett Lot College of Charleston 6
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