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 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());
}
} |
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 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());
}
} |
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.