How to Convert a List of Custom Class Objects to a List of Strings Using Java 8 Lambdas?

How can I convert a list of custom class objects to a list of strings using Java 8 lambda expressions?

List<String> tmpAddresses = new ArrayList<>();
for (User user : users) {
    tmpAddresses.add(user.getAddress());
}

Java 8 introduced the Stream API and lambda expressions, making it easier to work with collections. Here’s how to use these features to convert a list of custom class objects into a list of strings.

List<String> tmpAddresses = users.stream()
    .map(User::getAddress) // Method reference for clarity
    .collect(Collectors.toList());

Causes

• The legacy approach involves using loops and manual collection management.
• Java 8 provides more concise and readable syntax using streams.

Solutions

• Utilize `stream()` to create a stream from the list of objects.
• Use `map()` to transform each object into the desired string using a method reference or a lambda expression.
• Collect the results into a list using `collect(Collectors.toList())`.

Mistake: Using the wrong method to collect results after mapping.

Solution: Ensure to use `collect(Collectors.toList())` to gather results into a new list.

Mistake: Forgetting to import the required classes for streams and collectors.

Solution: Add imports: `import java.util.stream.Collectors;` and `import java.util.List;`.