Java 中的 ConcurrentHashMap size()方法

原文:https://www . geeksforgeeks . org/concurrenthashmap-size-method-in-Java/

java . util . concurrent . concurrenthashmap . size()方法是 Java 中的一个内置函数，它计算该映射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，该值表示该映射中键值映射的数量。

下面程序举例说明使用大小()的方法:

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

程序二:

// 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:

The number of key-value mappings is 6

参考:https://docs . Oracle . com/javase/7/docs/API/Java/util/concurrenthashmap . html # size()

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