Map remove() Method in Java with Examples

This method is used to remove the mapping for a key from this map if it is present in the map. 

Syntax: 

V remove(Object key)

Parameters: This method has the only argument key, whose mapping is to be removed from the map.
Returns: This method returns the value to which this map previously associated the key, or null if the map contained no mapping for the key.
Below programs show the implementation of int remove() method.
Program 1:

Java

// Java code to show the implementation of
// remove method in Map interface
import java.util.*;
public class GfG {

    // Driver code
    public static void main(String[] args)
    {

        // Initializing a Map of type HashMap
        Map<Integer, String> map = new HashMap<>();
        map.put(1, "One");
        map.put(3, "Three");
        map.put(5, "Five");
        map.put(7, "Seven");
        map.put(9, "Nine");
        System.out.println(map);

        map.remove(3);

        System.out.println(map);

        // If it doesn't exists, returns
        // null and does not affects the map
        map.remove(2);

        System.out.println(map);
    }
}

Output:

{1=One, 3=Three, 5=Five, 7=Seven, 9=Nine}
{1=One, 5=Five, 7=Seven, 9=Nine}
{1=One, 5=Five, 7=Seven, 9=Nine}

Program 2: Below is the code to show implementation of put(). 

Java

// Java code to show the implementation of
// remove method in Map interface
import java.util.*;
public class GfG {

    // Driver code
    public static void main(String[] args)
    {

        // Initializing a Map of type HashMap
        Map<String, String> map = new HashMap<>();
        map.put("1", "One");
        map.put("3", "Three");
        map.put("5", "Five");
        map.put("7", "Seven");
        map.put("9", "Nine");
        System.out.println(map);

        map.remove("3");

        System.out.println(map);
    }
}

Output:

{1=One, 3=Three, 5=Five, 7=Seven, 9=Nine}
{1=One, 5=Five, 7=Seven, 9=Nine}

Reference: 
Oracle Docs