Java EnumMap putAll() Method

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Description

The Java EnumMap putAll(Map<? extends K,? extends V> m) method copies all of the mappings from the specified map to this map. Older values are replaced.

Declaration

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

public void putAll(Map<? extends K,? extends V> m)

Parameters

m − the mappings to be stored in this map

Return Value

This method does not return any value.

Exception

NullPointerException − the specified map is null, or if one or more keys in the specified map are null

Adding Multiple Values to an EnumMap of Enum, Integer Pairs Example

The following example shows the usage of Java EnumMap putAll() method to populate the EnumMap instance. We've created a enum Numbers. Then Two EnumMap instance are created of enum Numbers and Integer. Few entries are added and enumMap is printed. Using putAll() method, enumMap is populated with values of first enumMap and 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);
		 
      EnumMap<Numbers,Integer> map2 = 
         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); 

      // copy the map
      map2.putAll(map);

      // print the map2
      System.out.println(map2); 
   }
}

Output

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

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

Adding Multiple Values to an EnumMap of Enum, String Pairs Example

The following example shows the usage of Java EnumMap putAll() method to populate the EnumMap instance. We've created a enum Numbers. Then Two EnumMap instance are created of enum Numbers and Strings. Few entries are added and enumMap is printed. Using putAll() method, enumMap is populated with values of first enumMap and 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);

      EnumMap<Numbers,String> map2 = 
         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); 

      // copy the map
      map2.putAll(map);

      // print the map2
      System.out.println(map2);  
   }
}

Output

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

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

Adding Multiple Values to an EnumMap of Enum, Object Pairs Example

The following example shows the usage of Java EnumMap putAll() method to populate the EnumMap instance. We've created a enum Numbers. Then Two EnumMap instance are created of enum Numbers and Student objects. Few entries are added and enumMap is printed. Using putAll() method, enumMap is populated with values of first enumMap and 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);

      EnumMap<Numbers,Student> map2 = 
         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); 

      // copy the map
      map2.putAll(map);

      // print the map2
      System.out.println(map2); 
   }
}
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 ]}
{ONE=[ 1, Julie ], TWO=[ 2, Robert ], THREE=[ 3, Adam ], FOUR=[ 4, Jene ]}