Java EnumMap remove() Method

Description

The Java EnumMap remove(Object key) method removes the mapping for this key from this map if present.

Declaration

Following is the declaration for java.util.EnumMap.remove() method

public V remove(Object key)

Parameters

key − the key whose mapping is to be removed from the map

Return Value

This method returns the previous value associated with specified key, or null if there was no entry for key.

Exception

NA

Removing A Value from an EnumMap of Enum, Integer Pairs Example

The following example shows the usage of Java EnumMap remove(Object) method to remove a value from the EnumMap instance based on a key passed. We've created a enum Numbers. Then EnumMap is created of enum Numbers and Integer. Few entries are added and enumMap is printed. Using remove() method, a value of enumMap is remove and enumMap is printed.

package com.tutorialspoint;

import java.util.EnumMap;

public class EnumMapDemo {
   
   // create an enum
   public enum Numbers{ONE, TWO, THREE, FOUR, FIVE}; 

   public static void main(String[] args) {
      
      EnumMap<Numbers,Integer> map = 
         new EnumMap<>(Numbers.class);

      // associate values in map
      map.put(Numbers.ONE, 1);
      map.put(Numbers.TWO, 2);
      map.put(Numbers.THREE,3);
      map.put(Numbers.FOUR, 4);

      // print the whole map
      System.out.println(map); 

      // remove a value based on a key
      System.out.println(map.remove(Numbers.TWO));
	  
      // print the map again
      System.out.println(map); 
   }
}

Output

Let us compile and run the above program, this will produce the following result −

{ONE=1, TWO=2, THREE=3, FOUR=4}
2
{ONE=1, THREE=3, FOUR=4}

Removing A Value from an EnumMap of Enum, String Pairs Example

The following example shows the usage of Java EnumMap remove(Object) method to remove a value from the EnumMap instance based on a key passed. We've created a enum Numbers. Then EnumMap is created of enum Numbers and Strings. Few entries are added and enumMap is printed. Using remove() method, a value of enumMap is remove and enumMap is printed.

package com.tutorialspoint;

import java.util.EnumMap;

public class EnumMapDemo {
   
   // create an enum
   public enum Numbers{ONE, TWO, THREE, FOUR, FIVE}; 

   public static void main(String[] args) {
      
      EnumMap<Numbers,String> map = 
         new EnumMap<>(Numbers.class);

      // associate values in map
      map.put(Numbers.ONE, "1");
      map.put(Numbers.TWO, "2");
      map.put(Numbers.THREE,"3");
      map.put(Numbers.FOUR, "4");

      // print the whole map
      System.out.println(map); 

      // remove a value based on a key
      System.out.println(map.remove(Numbers.TWO));
	  
      // print the map again
      System.out.println(map);
   }
}

Output

Let us compile and run the above program, this will produce the following result −

{ONE=1, TWO=2, THREE=3, FOUR=4}
2
{ONE=1, THREE=3, FOUR=4}

Removing A Value from an EnumMap of Enum, Object Pairs Example

The following example shows the usage of Java EnumMap remove(Object) method to remove a value from the EnumMap instance based on a key passed. We've created a enum Numbers. Then EnumMap is created of enum Numbers and Student objects. Few entries are added and enumMap is printed. Using remove() method, a value of enumMap is remove and enumMap is printed.

package com.tutorialspoint;

import java.util.EnumMap;

public class EnumMapDemo {
   
   // create an enum
   public enum Numbers{ONE, TWO, THREE, FOUR, FIVE}; 

   public static void main(String[] args) {
      
      EnumMap<Numbers,Student> map = 
         new EnumMap<>(Numbers.class);

      // associate values in map
      map.put(Numbers.ONE, new Student(1, "Julie"));
      map.put(Numbers.TWO, new Student(2, "Robert"));
      map.put(Numbers.THREE,new Student(3, "Adam"));
      map.put(Numbers.FOUR, new Student(4, "Jene"));

      // print the whole map
      System.out.println(map); 

      // remove a value based on a key
      System.out.println(map.remove(Numbers.TWO));
	  
      // print the map again
      System.out.println(map); 
   }
}
class Student {
   int rollNo;
   String name;

   Student(int rollNo, String name){
      this.rollNo = rollNo;
      this.name = name;
   }

   @Override
   public String toString() {
      return "[ " + this.rollNo + ", " + this.name + " ]";
   }
}

Output

Let us compile and run the above program, this will produce the following result −

{ONE=[ 1, Julie ], TWO=[ 2, Robert ], THREE=[ 3, Adam ], FOUR=[ 4, Jene ]}
[ 2, Robert ]
{ONE=[ 1, Julie ], THREE=[ 3, Adam ], FOUR=[ 4, Jene ]}