What is the EnumMap.clear() method in Java?

EnumMap is similar to Map, except EnumMap only takes the Enum type as a key. Also, all the keys must be from a single Enum type.

The clear() method of the EnumMap class removes all of the key and value mappings from a specified EnumMap object. When we call this method, the EnumMap object becomes empty.

Syntax

public void clear()

This method doesn’t take any parameters and does not return a value.

Code

The code below shows how we can use the clear() method.

import java.util.EnumMap;
class Clear {
    enum Days{
      MON, TUE, WED, THUR, FRI, SAT, SUN 
    };
    public static void main( String args[] ) {
        EnumMap<Days, String> gymSchedule = new EnumMap<>(Days.class);
        gymSchedule.put(Days.MON, "chest");
        gymSchedule.put(Days.TUE, "shoulder");
        gymSchedule.put(Days.WED, "arms");
        System.out.println( "The map is" +  gymSchedule);
        gymSchedule.clear();
        System.out.println( "\nAfter calling clear metthod.\nThe map is" +  gymSchedule);
    }
}

Code explanation

  • Line 1: We import the EnumMap class.

  • Line 3: We create an enum named Days for the days of the week.

  • Lines 7 to 11: We create an EnumMap object and use the put() method to add three mappings (Days.MON="chest", Days.MON="shoulder", Days.WED="arms") to the map.

  • Line 12: We use the clear() method to remove all mappings from the map. This makes the map empty.

  • Line 13: We print the map to ensure that it’s empty.

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