How to Output First Name Using Lambda in Java

Learn how to effectively output a person's `first name` using lambda expressions in Java, especially for individuals under 15 years old.
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Outputting First Names with Lambda Expressions in Java

As a newcomer to Java, you may find yourself grappling with how to manipulate data efficiently. One common requirement is to extract and display specific information from a list of objects. In today’s post, we will tackle the challenge of outputting the first names of individuals who are younger than 15 years old. This process involves understanding how to utilize lambda expressions effectively in Java.

The Problem

You have a list of people, and you want to print the first names of those who are under 15 years old. You tried to access the first names directly from the list, but encountered difficulties, as direct property access isn’t allowed for the way you were attempting it. Let's explore how to solve this issue step-by-step.

Understanding the Code Structure

Before diving into the solution, let’s revisit the relevant parts of your initial code:

Reading Data: You read data from a CSV file to create a list of Person objects.

Filtering Data: You use the FindCompulsorySchooling method to filter out people younger than 15 years based on their birthdates.

Output Requirements: The goal is to output the first names of those filtered persons.

The Solution

1. Consumer Interface

To print the first names, it’s essential to understand how Java handles lists and streams. The forEach method requires a Consumer, which means it needs something that can accept a Person object in turn.

You can achieve this in two main ways:

Using a Named Consumer Class: You can create a class that implements the Consumer interface.

Using Lambda Expressions: A more concise method in modern Java is to use a lambda expression.

Named Consumer Class Approach

Here’s how you can define a named consumer class within your Main class for outputting first names:

[[See Video to Reveal this Text or Code Snippet]]

This class implements the Consumer interface and overrides the accept method to specify what to do with each Person object.

Lambda Expression Approach

Alternatively, you can simplify the code using a lambda expression:

[[See Video to Reveal this Text or Code Snippet]]

This concise line of code effectively accomplishes the same task as the previous consumer class.

2. Implementing in the Main Method

With either approach, you can use it in your main method like this:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By understanding how to use Consumer and lambda expressions, you can effectively print the first names of individuals younger than 15 years of age from a list of Person objects. This knowledge not only simplifies your code but also embraces the modern practices of Java programming.

Now you’re equipped with the tools to manipulate data easily and efficiently in Java! Happy coding!