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TreeMap clear() Method in Java

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  • Last Updated : 28 Jun, 2018
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The java.util.TreeMap.clear() method in Java is used to clear and remove all of the elements or mappings from a specified TreeMap.

Syntax:

Tree_Map.clear()

Parameters: The method does not accept any parameters.

Return Value: The method does not return any value.

Below programs are used to illustrate the working of java.util.TreeMap.clear() Method:
Program 1: Mapping String Values to Integer Keys.




// Java code to illustrate the clear() 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);
  
        // Clearing the tree map using clear()
        tree_map.clear();
  
        // Displaying the final TreeMap
        System.out.println("Finally the map looks like: " + tree_map);
    }
}

Output:

Initial Mappings are: {10=Geeks, 15=4, 20=Geeks, 25=Welcomes, 30=You}
Finally the map looks like this: {}

Program 2: Mapping Integer Values to String Keys.




// Java code to illustrate the clear() 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);
  
        // Clearing the tree map using clear()
        tree_map.clear();
  
        // Displaying the final TreeMap
        System.out.println("Finally the map looks like: " + tree_map);
    }
}

Output:

Initial Mappings are: {4=15, Geeks=20, Welcomes=25, You=30}
Finally the map looks like: {}

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


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