TreeMap size() Method in Java

The java.util.TreeMap.size() method of TreeMap 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:

Tree_Map.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 java.util.TreeMap.size():
Program 1: Mapping String Values to Integer Keys.



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// Java code to illustrate the size() method
import java.util.*;
  
public class Tree_Map_Demo {
    public static void main(String[] args)
    {
  
        // Creating an empty TreeMap
        TreeMap<Integer, String> tree_map = new TreeMap<Integer, String>();
  
        // Mapping string values to int keys
        tree_map.put(10, "Geeks");
        tree_map.put(15, "4");
        tree_map.put(20, "Geeks");
        tree_map.put(25, "Welcomes");
        tree_map.put(30, "You");
  
        // Displaying the TreeMap
        System.out.println("Initial Mappings are: " + tree_map);
  
        // Displaying the size of the map
        System.out.println("The size of the map is " + tree_map.size());
    }
}

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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.

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// Java code to illustrate the size() method
import java.util.*;
  
public class Tree_Map_Demo {
    public static void main(String[] args)
    {
  
        // Creating an empty TreeMap
        TreeMap<String, Integer> tree_map = new TreeMap<String, Integer>();
  
        // Mapping int values to string keys
        tree_map.put("Geeks", 10);
        tree_map.put("4", 15);
        tree_map.put("Geeks", 20);
        tree_map.put("Welcomes", 25);
        tree_map.put("You", 30);
  
        // Displaying the TreeMap
        System.out.println("Initial Mappings are: " + tree_map);
  
        // Displaying the size of the map
        System.out.println("The size of the map is " + tree_map.size());
    }
}

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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.

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