Converting HashMap to ArrayList in java

Converting HashMap to ArrayList in java

To convert a HashMap to an ArrayList in Java, you can follow these steps:

  1. Initialize an ArrayList to hold the values from the HashMap.
  2. Iterate over the HashMap and add its values to the ArrayList.

Here's an example of how to do this:

import java.util.ArrayList; import java.util.HashMap; import java.util.Map; public class HashMapToArrayListExample { public static void main(String[] args) { // Create a HashMap HashMap<Integer, String> hashMap = new HashMap<>(); // Add some key-value pairs to the HashMap hashMap.put(1, "One"); hashMap.put(2, "Two"); hashMap.put(3, "Three"); hashMap.put(4, "Four"); // Convert the HashMap to an ArrayList ArrayList<String> arrayList = new ArrayList<>(hashMap.values()); // Print the ArrayList System.out.println("ArrayList from HashMap values: " + arrayList); } }

In this example:

  1. We create a HashMap named hashMap and add some key-value pairs to it.

  2. We create an ArrayList named arrayList and initialize it with the values from the HashMap using hashMap.values(). The values() method returns a Collection view of the values contained in the HashMap.

  3. Finally, we print the ArrayList, which contains the values from the HashMap. The order of elements in the ArrayList may not be the same as the order in the HashMap, as HashMap does not guarantee a specific order.

This code will convert the values of the HashMap into an ArrayList. If you need to convert the keys or key-value pairs, you can follow a similar approach by iterating over the HashMap and adding the desired elements to the ArrayList.

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