// Product class
class Pizza {
    private String dough;
    private String sauce;
    private String topping;

    // Private constructor to enforce the use of Builder
    private Pizza(PizzaBuilder builder) {
        this.dough = builder.dough;
        this.sauce = builder.sauce;
        this.topping = builder.topping;
    }

    @Override
    public String toString() {
        return "Pizza with " + dough + " dough, "
         + sauce + " sauce, and " + topping + " topping.";
    }

    public static class PizzaBuilder {
        private String dough;
        private String sauce;
        private String topping;

        public PizzaBuilder dough(String dough) {
            this.dough = dough;
            return this;
        }

        public PizzaBuilder sauce(String sauce) {
            this.sauce = sauce;
            return this;
        }
        
        public PizzaBuilder topping(String topping) {
            this.topping = topping;
            return this;
        }

        public Pizza build() {
            return new Pizza(this);
        }
    }
}

public class Main {
    public static void main(String[] args) {
        Pizza myPizza = new Pizza.PizzaBuilder()
                .dough("Thin Crust")
                .sauce("Tomato")
                .topping("Cheese")
                .build();

        System.out.println(myPizza);

        String orderType = "Veggie";

        Pizza.PizzaBuilder pizzaBuilder
         = new Pizza.PizzaBuilder().dough("Regular");

        pizzaBuilder.sauce("Pesto");

        if (orderType.equals("Veggie")) {
            pizzaBuilder.topping("Vegetables");
        } else {
            pizzaBuilder.topping("Pepperoni");
        }

        Pizza customPizza = pizzaBuilder.build();
        System.out.println(customPizza);
    }
}

Pizza with Thin Crust dough, Tomato sauce, and Cheese topping.
Pizza with Regular dough, Pesto sauce, and Vegetables topping.

import java.util.HashMap;
import java.util.Map;

// Product class
public class HttpRequest {
    private String method;
    private String url;
    private Map<String, String> headers;
    private Map<String, String> parameters;
    private String body;
    
    // private constructor
    private HttpRequest(Builder builder) {
        this.method = builder.method;
        this.url = builder.url;
        this.headers = builder.headers;
        this.parameters = builder.parameters;
        this.body = builder.body;
    }
    
    @Override
    public String toString() {
        return "HttpRequest [method=" + method + ", url=" + url + 
               ", headers=" + headers + ", parameters=" + parameters + 
               ", body=" + body + "]";
    }

    public static class Builder {
        private String method;
        private String url;
        private Map<String, String> headers = new HashMap<>();
        private Map<String, String> parameters = new HashMap<>();
        private String body;

        public Builder(String method, String url) {
            this.method = method;
            this.url = url;
        }

        public Builder addHeader(String key, String value) {
            this.headers.put(key, value);
            return this; }

        public Builder addParameter(String key, String value) {
            this.parameters.put(key, value);
            return this; }

        public Builder setBody(String body) {
            this.body = body;
            return this; }

        public HttpRequest build() {
            return new HttpRequest(this); }
    }
}

public class Main {
    public static void main(String[] args) {
    
        HttpRequest getRequest = new HttpRequest.Builder(
            "GET", "<https://example.com/api>")
            .addHeader("Authorization", "Bearer token")
            .addParameter("query", "builder-pattern")
            .build();

        HttpRequest postRequest = new HttpRequest.Builder(
            "POST", "<https://example.com/api>")
            .addHeader("Authorization", "Bearer token")
            .setBody("{ \\"name\\": \\"John\\", \\"age\\": 30 }")
            .build();
        
        System.out.println(getRequest);
        System.out.println(postRequest);
    }
}

HttpRequest [method=GET, url=https://example.com/api,
 headers={Authorization=Bearer token}, parameters={query=builder-pattern},
 body=null]
 
HttpRequest [method=POST, url=https://example.com/api,
 headers={Authorization=Bearer token}, parameters={},
 body={ "name": "John", "age": 30 }]