What is the EnumMap.remove(key,value) method in Java?

EnumMap is similar to Map, except that EnumMap only takes the Enum type as keys. Also, all the keys must be from a single enum type. For further details, refer here.

In EnumMap, we can use the remove method to remove the mapping, given that the specified key-value mapping is present.

Syntax

public boolean remove(Object key, Value. v)

Parameters

The key and value whose mapping is to be removed are passed as parameters.

Return value

This method returns true if the mapping is removed.

Code

The following example shows how to use the remove method.

import java.util.EnumMap;
class Remove {
    enum Subject {
      MATHS, SCIENCE, PROGRAMMING, ECONOMICS
    };
    public static void main( String args[] ) {
        EnumMap<Subject, Integer> map = new EnumMap<>(Subject.class);
        map.put(Subject.MATHS, 50);
        map.put(Subject.SCIENCE, 60);
        map.put(Subject.PROGRAMMING, 70);
        
        System.out.println("The map is -" + map );
        System.out.println("\nCalling remove(MATHS, 50)" );
        boolean isRemoved = map.remove(Subject.MATHS, 50);
        System.out.println("Is mapping removed -" + isRemoved);
        System.out.println("The map is -" + map );
        
        System.out.println("\nCalling remove(SCIENCE, 60)" );
        isRemoved = map.remove(Subject.SCIENCE, 20);
        System.out.println("Is mapping removed -" + isRemoved);
        System.out.println("The map is -" + map );
    }
}

Explanation

In the code above, we:

  • Create an Enum for the subjects with the name Subject.

  • Create an EnumMap with the name map.

  • Add three entries to the map.

  • Use the remove method to remove the mapping for the Subject.MATHS key and value 50. This method checks if there is an entry present for the Subject.MATHS key with the value 50. In our case, there is an entry, so the mapping is removed and the remove method returns true.

  • Use the remove method to remove the mapping for the Subject.SCIENCE key and value 20. This method checks if there is an entry present for the Subject.SCIENCE key with the value 20. In our case, there is no entry present, so the mapping remains unchanged and the remove method returns false.

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