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Merge Sets and Convert to List in Java

Last updated Apr 25, 2024

In this tutorial, we will explore an example in Java that demonstrates how to merge the values of two sets and convert them into a list. Managing collections efficiently is crucial in many programming scenarios, and this tutorial provides a practical solution to this common task.

Here's an example that demonstrates how to merge the values of two sets and convert them into a list in Java:

import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.stream.Collectors;

public class Example {

   public static void main(String[] args) {
      HashSet fruits = new HashSet<>();
      fruits.add("Grapes");
      fruits.add("Mango");
      fruits.add("Apple");
      fruits.add("Papaya");
      fruits.add("Pineapple");

      HashSet flowers = new HashSet<>();
      flowers.add("Tulip");
      flowers.add("Rose");
      flowers.add("Sunflower");
      flowers.add("Marigold");

      Map map = new HashMap<>();
      map.put("fruits", fruits);
      map.put("flowers", flowers);

      Set mergedSet = map.values().stream().flatMap(set -> ((Set) set).stream())
       .collect(Collectors.toSet());

      List list = new ArrayList<>(mergedSet);
      System.out.println(list);
   }

}

The output of the above code is as follows:

[Apple, Tulip, Grapes, Papaya, Mango, Rose, Pineapple, Sunflower, Marigold]

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Merge Sets and Convert to List in Java