Lambda Expressions in Java: iteration, filtering, and transformation

In this example, we have a list of names: “Tom”, “Richard”, and “Sarah”.
We demonstrate three different use cases of lambdas:

1. Iteration and Printing: We use the forEach method to iterate over the list and print each name with a greeting message. The lambda expression (name -> System.out.println("Hello, " + name)) is used to define the behavior.
2. Filtering: We use the forEach method along with a lambda expression to filter the list based on a condition. In this case, we filter out names that start with the letter “J” and add them to a separate list called filteredNames.
3. Transformation: We use the forEach method and a lambda expression to transform the list elements. Here, we calculate the length of each name and add the lengths to a separate list called nameLengths.

Finally, we print the filteredNames list and the nameLengths list to observe the results of the filtering and transformation operations.

import java.util.ArrayList;
import java.util.List;

public class LambdasExample {
    public static void main(String[] args) {
        List<String> names = new ArrayList<>();
        names.add("Tom");
        names.add("Richard");
        names.add("Sarah");

        // Using a lambda expression to iterate over the list and print each name
        names.forEach(name -> System.out.println("Hello, " + name));

        // Using a lambda expression to filter the list based on a condition
        List<String> filteredNames = new ArrayList<>();
        names.forEach(name -> {
            if (name.startsWith("J")) {
                filteredNames.add(name);
            }
        });

        // Using a lambda expression to transform the list elements
        List<Integer> nameLengths = new ArrayList<>();
        names.forEach(name -> nameLengths.add(name.length()));

        System.out.println("Filtered Names: " + filteredNames);
        System.out.println("Name Lengths: " + nameLengths);
    }
}