Java EnumMap size()方法

Java.util.EnumMap.size()方法用于了解Map的大小或Map中存在的元素数量。

语法

Enum_Map.size()

参数： 该方法不接受任何参数。

返回值： 该方法返回Map的大小。

以下程序说明了size()函数的工作原理：

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);
    }
}

输出：

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);
    }
}

输出：

The EnumMap: {India_today=69, United_States_today=1073}
The EnumMap: {India_today=69}
Size of map: 1