网捷达

The AbstractMap.size() method of AbstractMap class is used to get the size of the map which refers to the number of the key-value pair or mappings in the Map. Syntax:

AbstractMap.size()

Parameters: The method does not take any parameters. Return Value: The method returns the size of the map which also means the number of key-value pairs present in the map. Below programs illustrates the working of AbstractMap.size(): Program 1: Mapping String Values to Integer Keys.

Java

// Java code to illustrate the size() method

import java.util.*;

public class Abstract_Map_Demo {
    public static void main(String[] args)
    {

        // Creating an empty AbstractMap
        AbstractMap<Integer, String>
            abs_map = new TreeMap<Integer, String>();

        // Mapping string values to int keys
        abs_map.put(10, "Geeks");
        abs_map.put(15, "4");
        abs_map.put(20, "Geeks");
        abs_map.put(25, "Welcomes");
        abs_map.put(30, "You");

        // Displaying the AbstractMap
        System.out.println("Initial Mappings are: "
                           + abs_map);

        // Displaying the size of the map
        System.out.println("The size of the map is "
                           + abs_map.size());
    }
}

Output:

Initial Mappings are: {10=Geeks, 15=4, 20=Geeks, 25=Welcomes, 30=You}
The size of the map is 5

Program 2: Mapping Integer Values to String Keys.

Java

// Java code to illustrate the size() method

import java.util.*;

public class Abstract_Map_Demo {
    public static void main(String[] args)
    {

        // Creating an empty AbstractMap
        AbstractMap<String, Integer>
            abs_map = new TreeMap<String, Integer>();

        // Mapping int values to string keys
        abs_map.put("Geeks", 10);
        abs_map.put("4", 15);
        abs_map.put("Geeks", 20);
        abs_map.put("Welcomes", 25);
        abs_map.put("You", 30);

        // Displaying the AbstractMap
        System.out.println("Initial Mappings are: "
                           + abs_map);

        // Displaying the size of the map
        System.out.println("The size of the map is "
                           + abs_map.size());
    }
}

Output:

Initial Mappings are: {4=15, Geeks=20, Welcomes=25, You=30}
The size of the map is 4

Note: The same operation can be performed with any type of Mappings with variation and combination of different data types.

AbstractMap size() Method in Java with Examples

Explore