Conversion of Java Maps to List

Java 8Object Oriented ProgrammingProgramming

At first, let us create a Java Map and initialize −

Map<Integer, String> map = new HashMap<>();
map.put(1, "Tom");
map.put(2, "John");
map.put(3, "Kevin");
map.put(4, "Jacob");
map.put(5, "Ryan");

Now, convert the Map to List −

ArrayList<Integer> key = new ArrayList<Integer>(map.keySet());
ArrayList<String> value = new ArrayList<String>(map.values());

Example

Following is the program to convert Maps to List in Java −

import java.util.HashMap;
import java.util.ArrayList;
import java.util.Map;
public class Demo {
   public static void main(String args[]) {
      Map<Integer, String> map = new HashMap<>();
      map.put(1, "Tom");
      map.put(2, "John");
      map.put(3, "Kevin");
      map.put(4, "Jacob");
      map.put(5, "Ryan");
      map.put(6, "Bradley");
      map.put(7, "Andy");
      map.put(8, "Tim");
      System.out.println("HashMap = " + map);
      ArrayList<Integer> key = new ArrayList<Integer>(map.keySet());
      ArrayList<String> value = new ArrayList<String>(map.values());
      System.out.println("\nList (Map Keys) = "+key);
      System.out.println("List (Map Values) = "+value);
   }
}

Output

HashMap = {1=Tom, 2=John, 3=Kevin, 4=Jacob, 5=Ryan, 6=Bradley, 7=Andy, 8=Tim}
List (Map Keys) = [1, 2, 3, 4, 5, 6, 7, 8]
List (Map Values) = [Tom, John, Kevin, Jacob, Ryan, Bradley, Andy, Tim]
raja
Published on 25-Sep-2019 08:27:22
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