Java ConcurrentHashMap size()方法

java.util.concurrent.ConcurrentHashMap.size() 方法是Java中的一个内置函数，它计算该地图中键值映射的数量并返回整数值。

语法

public int size()

返回值： 该函数返回一个整数值，表示该地图中键值映射的数量。

下面的程序说明了 size() 方法的使用。

程序 1:

// Java Program Demonstrate size()
// method of ConcurrentHashMap
  
import java.util.concurrent.*;
  
class GFG {
    public static void main(String[] args)
    {
  
        ConcurrentHashMap<Integer, String>
            chm = new ConcurrentHashMap<Integer, String>();
  
        chm.put(100, "Geeks");
        chm.put(101, "for");
        chm.put(102, "Geeks");
  
        // Display the number of
        // key-value mappings
        System.out.println("The number of "
                           + "key-value mappings is "
                           + chm.size());
    }
}

输出:

The number of key-value mappings is 3

计划2。

// Java Program Demonstrate size()
// method of ConcurrentHashMap
  
import java.util.concurrent.*;
  
class GFG {
    public static void main(String[] args)
    {
  
        ConcurrentHashMap<Integer, Integer>
            chm = new ConcurrentHashMap<Integer, Integer>();
  
        chm.put(1, 100);
        chm.put(2, 200);
        chm.put(3, 300);
        chm.put(4, 400);
        chm.put(5, 500);
        chm.put(6, 600);
  
        // Display the number of
        // key-value mappings
        System.out.println("The number of "
                           + "key-value mappings is "
                           + chm.size());
    }
}

输出: