Java 中的 EnumMap size()方法
原文:https://www.geeksforgeeks.org/enummap-size-method-in-java/
Java 中的 Java.util.EnumMap.size()方法用于知道地图的大小或地图中存在的元素数量。
语法:
Enum_Map.size()
参数:该方法不取任何参数。
返回值:该方法返回地图的大小。
以下程序说明了 size()函数的工作: 程序 1:
// Java program to demonstrate size()
import java.util.*;
// An enum of geeksforgeeks
public enum gfg {
India_today,
United_States_today
}
;
class Enum_demo {
public static void main(String[] args)
{
EnumMap<gfg, Integer> mp = new
EnumMap<gfg, Integer>(gfg.class);
// Values are associated
mp.put(gfg.India_today, 69);
mp.put(gfg.United_States_today, 1073);
// Prints the map
System.out.println("The EnumMap: " + mp);
// Store the size of the map
int numberOf_kv = mp.size();
// Prints the map_size
System.out.println("Size of map: " + numberOf_kv);
}
}
Output:
The EnumMap: {India_today=69, United_States_today=1073}
Size of map: 2
程序 2:
// Java program to demonstrate size()
import java.util.*;
// An enum of geeksforgeeks
public enum gfg {
India_today,
United_States_today
}
;
class Enum_demo {
public static void main(String[] args)
{
EnumMap<gfg, Integer> mp = new
EnumMap<gfg, Integer>(gfg.class);
// Values are associated
mp.put(gfg.India_today, 69);
mp.put(gfg.United_States_today, 1073);
// Prints the map
System.out.println("The EnumMap: " + mp);
// Remove mapping of this key
mp.remove(gfg.United_States_today);
// Prints the final map
System.out.println("The EnumMap: " + mp);
// Store the size pf map after removal of
// The key
int numberOf_kv = mp.size();
// Prints the map_size
System.out.println("Size of map: " + numberOf_kv);
}
}
Output:
The EnumMap: {India_today=69, United_States_today=1073}
The EnumMap: {India_today=69}
Size of map: 1
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