AbstractMap remove() Method in Java with Examples

The AbstractMap.remove() is an inbuilt method of AbstractMap class and is used to remove the mapping of any particular key from the map. It basically removes the values for any particular key in the Map.

Syntax:

AbstractMap.remove(Object key)

Parameters: The method takes one parameter key whose mapping is to be removed from the Map.

Return Value: The method returns the value that was previously mapped to the specified key if the key exists else the method returns NULL.

Below programs illustrates the working of AbstractMap.remove() method:

Program 1: When passing an existing key.

// Java code to illustrate the remove() 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 HashMap<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);

        // Removing the existing key mapping
        String
            returned_value
            = (String)abs_map.remove(20);

        // Verifying the returned value
        System.out.println("Returned value is: "
                           + returned_value);

        // Displayin the new map
        System.out.println("New map is: "
                           + abs_map);
    }
}

Output:

Initial Mappings are: {20=Geeks, 25=Welcomes, 10=Geeks, 30=You, 15=4}
Returned value is: Geeks
New map is: {25=Welcomes, 10=Geeks, 30=You, 15=4}

Program 2: When passing a new key.

// Java code to illustrate the remove() 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 HashMap<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);

        // Removing the new key mapping
        String
            returned_value
            = (String)abs_map.remove(50);

        // Verifying the returned value
        System.out.println("Returned value is: "
                           + returned_value);

        // Displayin the new map
        System.out.println("New map is: " + abs_map);
    }
}

Output:

Initial Mappings are: {20=Geeks, 25=Welcomes, 10=Geeks, 30=You, 15=4}
Returned value is: null
New map is: {20=Geeks, 25=Welcomes, 10=Geeks, 30=You, 15=4}

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