Builder pattern example Java 8

Builder pattern example Java 8

Here's an example of using the builder pattern in Java 8:

// A simple Person class with a constructor that takes name and age as parameters.
class Person {
private String name;
private int age;
public static class Builder {
private String name;
private int age = 0;
// Constructor that takes the required parameter (name).
public Builder(String name) {
this.name = name;
}
// Method to set the age.
public Builder age(int age) {
this.age = age;
return this; // This allows us to chain method calls.
}
// Method to get the built Person object.
public Person build() {
return new Person(this);
}
}
private Person(Builder builder) {
name = builder.name;
age = builder.age;
}
@Override
public String toString() {
return "Person{" +
"name='" + name + ''' +
", age=" + age +
'}';
}
}
public class BuilderPatternExample {
public static void main(String[] args) {
// Create a Person with the builder pattern.
Person person = new Person.Builder("John")
.age(30)
.build();
System.out.println(person.toString());
}
}

In this example, we have a Person class that has a constructor with two parameters: name and age. We also have an inner class called Builder which is used to build the Person object. This builder pattern allows us to create complex objects step by step.

We can create a new person object like this:

person = new Person.Builder("John")
.age(30)
.build();

This way, we have more control over how our Person objects are constructed and it makes the code easier to read and maintain.

Abstract builder pattern Java

I'd be happy to explain the Builder design pattern in Java!

What is the Builder Pattern?

The Builder pattern is a creational design pattern that allows you to construct complex objects step-by-step, separating the construction and representation of the object's internal state. This pattern helps solve the problem of building complex objects when their construction requires multiple steps or dependencies.

Problem Statement:

Suppose we're building a Java class, Car, that represents a vehicle with properties like color, model, year, and engineType. We want to create different types of cars (e.g., sports car, family sedan) with varying characteristics. Using traditional constructors or setters would lead to code duplication and make the object's construction more complicated.

Solution:

We'll use the Builder pattern to build a Car object in a step-by-step manner, allowing us to construct different types of cars without modifying the original class.

public class Car {
private String color;
private String model;
private int year;
private EngineType engineType;
public Car(Builder builder) {
this.color = builder.getColor();
this.model = builder.getModel();
this.year = builder.getYear();
this.engineType = builder.getEngineType();
}
public static class Builder {
private String color;
private String model;
private int year;
private EngineType engineType;
public Builder(String color) {
this.color = color;
}
public Builder model(String model) {
this.model = model;
return this;
}
public Builder year(int year) {
this.year = year;
return this;
}
public Builder engineType(EngineType engineType) {
this.engineType = engineType;
return this;
}
public Car build() {
return new Car(this);
}
}
}

How it Works:

Benefits:

The Builder pattern offers several advantages:

By using the Builder pattern in Java, you can efficiently construct complex objects while maintaining a clean, modular design.