Secret Recipe of the Template Method: Po Learns the Art of Structured Cooking

 

Gala at the Jade Palace

A grand gala was being held at the Jade Palace. The Furious Five were preparing, and Po was helping his father, Mr. Ping, in the kitchen. But as always, Po had questions.

Po (curious): "Dad, how do you always make the perfect noodle soup no matter what the ingredients are?"

Mr. Ping (smiling wisely): "Ah, my boy, that’s because I follow the secret recipe—a fixed template!"

Mr. Ping Reveals the Template Method Pattern

Mr. Ping: "Po, the Template Method Pattern is like my noodle recipe. The skeleton of the cooking steps stays the same, but the ingredients and spices can vary!"

Po: "Wait, you mean like... every dish has a beginning, middle, and end—but I can change what goes inside?"

Mr. Ping: "Exactly! The fixed steps are defined in a base class, but subclasses—or in our case, specific dishes—override the variable parts."

Traditional Template Method in Java (Classic OOP)

Java

 

public abstract class DishRecipe {
    // Template method
    public final void cookDish() {
        boilWater();
        addIngredients();
        addSpices();
        serve();
    }

    private void boilWater() {
        System.out.println("Boiling water...");
    }

    protected abstract void addIngredients();
    protected abstract void addSpices();

    private void serve() {
        System.out.println("Serving hot!");
    }
}

class NoodleSoup extends DishRecipe {
    protected void addIngredients() {
        System.out.println("Adding noodles, veggies, and tofu.");
    }

    protected void addSpices() {
        System.out.println("Adding soy sauce and pepper.");
    }
}

class DumplingSoup extends DishRecipe {
    protected void addIngredients() {
        System.out.println("Adding dumplings and bok choy.");
    }

    protected void addSpices() {
        System.out.println("Adding garlic and sesame oil.");
    }
}
public class TraditionalCookingMain {
    public static void main(String[] args) {
        DishRecipe noodle = new NoodleSoup();
        noodle.cookDish();

        System.out.println("\n---\n");

        DishRecipe dumpling = new DumplingSoup();
        dumpling.cookDish();
    }
}
//Output
Boiling water...
Adding noodles, veggies, and tofu.
Adding soy sauce and pepper.
Serving hot!

---

Boiling water...
Adding dumplings and bok choy.
Adding garlic and sesame oil.
Serving hot!

Po: "Whoa! So each dish keeps the boiling and serving, but mixes up the center part. Just like kung fu forms!"

Functional Template Method Style

Po: "Dad, can I make it more... functional?"

Mr. Ping: "Yes, my son. We now wield the power of higher-order functions."

Java

 

import java.util.function.Consumer;

public class FunctionalTemplate {

    public static <T> void prepareDish(T dishName, Runnable boil, Consumer<T> addIngredients, Consumer<T> addSpices, Runnable serve) {
        boil.run();
        addIngredients.accept(dishName);
        addSpices.accept(dishName);
        serve.run();
    }

    public static void main(String[] args) {
        prepareDish("Noodle Soup",
            () -> System.out.println("Boiling water..."),
            dish -> System.out.println("Adding noodles, veggies, and tofu to " + dish),
            dish -> System.out.println("Adding soy sauce and pepper to " + dish),
            () -> System.out.println("Serving hot!")
        );

        prepareDish("Dumpling Soup",
            () -> System.out.println("Boiling water..."),
            dish -> System.out.println("Adding dumplings and bok choy to " + dish),
            dish -> System.out.println("Adding garlic and sesame oil to " + dish),
            () -> System.out.println("Serving hot!")
        );
    }
}

Po: "Look dad! Now we can cook anything, as long as we plug in the steps! It's like building recipes with Lego blocks!"

Mr. Ping (beaming): "Ah, my son. You are now a chef who understands both structure and flavor."

Real-World Use Case – Coffee Brewing Machines

Po: “Dad, Now I want to build the perfect coffee-making machine, just like our noodle soup recipe!”

Mr. Ping: “Ah, coffee, the elixir of monks and night-coders! Use the same template method wisdom, my son.”

Step-by-Step Template – Java OOP Coffee Brewer 

Java

 

abstract class CoffeeMachine {
    // Template Method
    public final void brewCoffee() {
        boilWater();
        addCoffeeBeans();
        brew();
        pourInCup();
    }

    private void boilWater() {
        System.out.println("Boiling water...");
    }

    protected abstract void addCoffeeBeans();
    protected abstract void brew();

    private void pourInCup() {
        System.out.println("Pouring into cup.");
    }
}

class EspressoMachine extends CoffeeMachine {
    protected void addCoffeeBeans() {
        System.out.println("Adding finely ground espresso beans.");
    }

    protected void brew() {
        System.out.println("Brewing espresso under high pressure.");
    }
}

class DripCoffeeMachine extends CoffeeMachine {
    protected void addCoffeeBeans() {
        System.out.println("Adding medium ground coffee.");
    }

    protected void brew() {
        System.out.println("Dripping hot water through the grounds.");
    }
}
public class CoffeeMain {
    public static void main(String[] args) {
        CoffeeMachine espresso = new EspressoMachine();
        espresso.brewCoffee();

        System.out.println("\n---\n");

        CoffeeMachine drip = new DripCoffeeMachine();
        drip.brewCoffee();
    }
}
//Ouput
Boiling water...
Adding finely ground espresso beans.
Brewing espresso under high pressure.
Pouring into cup.

---

Boiling water...
Adding medium ground coffee.
Dripping hot water through the grounds.
Pouring into cup.

Functional & Generic Coffee Brewing (Higher-Order Zen)

Po, feeling enlightened, says:

Po: “Dad! What if I want to make Green Tea or Hot Chocolate too?”

Mr. Ping (smirking): “Ahhh... Time to use the Generic Template of Harmony™!”

Functional Java Template for Any Beverage

Java

 

import java.util.function.Consumer;

public class BeverageBrewer {

    public static <T> void brew(T name, Runnable boil, Consumer<T> addIngredients, Consumer<T> brewMethod, Runnable pour) {
        boil.run();
        addIngredients.accept(name);
        brewMethod.accept(name);
        pour.run();
    }

    public static void main(String[] args) {
        brew("Espresso",
            () -> System.out.println("Boiling water..."),
            drink -> System.out.println("Adding espresso grounds to " + drink),
            drink -> System.out.println("Brewing under pressure for " + drink),
            () -> System.out.println("Pouring into espresso cup.")
        );

        System.out.println("\n---\n");

        brew("Green Tea",
            () -> System.out.println("Boiling water..."),
            drink -> System.out.println("Adding green tea leaves to " + drink),
            drink -> System.out.println("Steeping " + drink + " gently."),
            () -> System.out.println("Pouring into tea cup.")
        );
    }
}
//Output
Boiling water...
Adding espresso grounds to Espresso
Brewing under pressure for Espresso
Pouring into espresso cup.

---

Boiling water...
Adding green tea leaves to Green Tea
Steeping Green Tea gently.
Pouring into tea cup.

Mr. Ping’s Brewing Wisdom

“In code as in cooking, keep your recipe fixed… but let your ingredients dance.”

• Template Pattern gives you structure.

• Higher-order functions give you flexibility.

• Use both, and your code becomes as tasty as dumplings dipped in wisdom!

  
  

Mr. Ping: "Po, a great chef doesn't just follow steps. He defines the structure—but lets each ingredient bring its own soul."

Po: "And I shall pass down the Template protocol to my children’s children’s children!

Other Articles in this Series.

================================

1.Kung Fu Code: Master Shifu Teaches Strategy Pattern to Po – the Functional Way!

2. Code of Shadows:Mastering Decorator Pattern in Java – Po & Shifu’s Thriller Story of Clean Code

Read more

Code of Shadows:Mastering Decorator Pattern in Java – Po & Shifu’s Thriller Story of Clean Code

 

The Logging Conspiracy 

It was a cold, misty morning at the Jade Palace. The silence was broken not by combat… but by a mysterious glitch in the logs.

Po (rushing in): "Shifu! The logs… they're missing timestamps!"

Shifu (narrowing his eyes): "This is no accident, Po. This is a breach in the sacred code path. The timekeeper has been silenced."

Traditional OOP Decorator

Shifu unfurled an old Java scroll:

//Interface
package com.javaonfly.designpatterns.decorator.oops;
public interface Loggable {

    public void logMessage(String message);
}
//Implementation
package com.javaonfly.designpatterns.decorator.oops.impl;
import com.javaonfly.designpatterns.decorator.oops.Loggable;
public class SimpleLogger implements Loggable {
    @Override
    public void logMessage(String message) {
        System.out.println(message);
    }
}
//Implementation
class TimestampLogger implements Loggable {
    private Loggable wrapped;

    public TimestampLogger(Loggable wrapped) {
        this.wrapped = wrapped;
    }

    public void logMessage(String message) {
        String timestamped = "[" + System.currentTimeMillis() + "] " + message;
        wrapped.logMessage(timestamped);
    }
}

//Calling the decorator
public class Logger {
    public static void main(String[] args){
        Loggable simpleLogger = new SimpleLogger();
        simpleLogger.logMessage("This is a simple log message.");

        Loggable timestampedLogger = new TimestampLogger(simpleLogger);
        timestampedLogger.logMessage("This is a timestamped log message.");
    }
}
//Output
This is a simple log message.
[1748594769477] This is a timestamped log message.

Po: "Wait, we’re creating all these classes just to add a timestamp?"

Shifu: "That is the illusion of control. Each wrapper adds bulk. True elegance lies in Functional Programming."

Functional Decorator Pattern with Lambdas

Shifu waved his staff and rewrote the scroll:

package com.javaonfly.designpatterns.decorator.fp;

import java.time.LocalDateTime;
import java.util.function.Function;

public class Logger {
  //higer order function
    public void decoratedLogMessage(Function<String, String> simpleLogger, Function<String, String> timestampLogger) {
        String message = simpleLogger.andThen(timestampLogger).apply("This is a log message.");
        System.out.println(message);
    }

    public static void main(String[] args){
        Logger logger = new Logger();

        Function<String, String> simpleLogger = message -> {
            System.out.println(message);
            return message;
        };

        Function<String, String> timestampLogger = message -> {
            String timestampedMessage =  "[" + System.currentTimeMillis() + "] " + ": " + message;
            return timestampedMessage;
        };

        logger.decoratedLogMessage(simpleLogger, timestampLogger);
    }
}
//Output
This is a log message.
[1748595357335] This is a log message.

Po (blinking): "So... no more wrappers, just function transformers?"

Shifu (nodding wisely): "Yes, Po. In Functional Programming, functions are first-class citizens. The Function<T, R> interface lets us compose behavior. Each transformation can be chained using andThen, like stacking skills in Kung Fu."

Breaking Down the Code – Functional Wisdom Explained

Po (scratching his head): "Shifu, what exactly is this Function<T, R> thing? Is it some kind of scroll?"

Shifu (gently): "Ah, Po. It is not a scroll. It is a powerful interface from the java.util.function package—a tool forged in the fires of Java 8."

"Function<T, R> represents a function that accepts an input of type T and produces a result of type R."

In our case:

Java

 

Function<String, String> simpleLogger

This means: “Take a String message, and return a modified String message.”

Each logger lambda—like simpleLogger and timestampLogger—does exactly that.

The Art of Composition — andThen

Po (eyes wide): "But how do they all work together? Like… kung fu moves in a combo?"

Shifu (smiling): "Yes. That combo is called composition. And the technique is called andThen."

Java

 

simpleLogger.andThen(timestampLogger)

This means:

1. First, execute simpleLogger, which prints the message and passes it on.

2. Then, take the result and pass it to timestampLogger, which adds the timestamp.

This is function chaining—the essence of functional design.

String message = simpleLogger
                    .andThen(timestampLogger)
                    .apply("This is a log message.");

Like chaining martial arts techniques, each function passes its result to the next—clean, fluid, precise.

Po: "So the message flows through each function like a river through stones?"

Shifu: "Exactly. That is the way of the Stream."

Functional Flow vs OOP Structure

Shifu (serenely): "Po, unlike the OOP approach where you must wrap one class inside another—creating bulky layers—the functional approach lets you decorate behavior on the fly, without classes or inheritance."

• No need to create SimpleLogger, TimestampLogger, or interfaces.

• Just use Function<String, String> lambdas and compose them.

The Secret to Clean Code

“A true master does not add weight to power. He adds precision to purpose.” – Master Shifu

This approach:

• Eliminates boilerplate.
• Encourages reusability.
• Enables testability (each function can be unit-tested in isolation).
• Supports dynamic behavior chaining.

Po's New Move: Making the Logger Generic

After mastering the basics, Po's eyes sparkled with curiosity.

Po: "Shifu, what if I want this technique to work with any type—not just strings?"

Shifu (with a deep breath): "Yes of course you can ! Try to write it, Dragon warrior."

Po meditated for a moment, and then rewrote the logger:

 public <T> void decoratedLogMessage(Function<T, T>... loggers) {
        Function<T, T> pipeline= Arrays.stream(loggers).sequential().reduce(Function.identity(), Function::andThen);
        T message = pipeline.apply((T) "This is a log message.");
        System.out.println(message);
    }

Po (bowing):

"Master Shifu, after learning to compose logging functions using Function<String, String>, I asked myself — what if I could decorate not just strings, but any type of data? Numbers, objects, anything! So I used generics and built this move..."

public <T> void decoratedLogMessage(Function<T, T>... loggers) 

"This declares a generic method where T can be any type — String, Integer, or even a custom User object.

The method takes a varargs of Function<T, T> — that means a flexible number of functions that take and return the same type."

Function<T, T> pipeline=
  Arrays.stream(loggers).sequential().reduce(Function.identity(), Function::andThen);

• "I stream all the logger functions and reduce them into a single pipeline function using Function::andThen.

• Function.identity() is the neutral starting point — like standing still before striking.

• Function::andThen chains each logger — like chaining combos in kung fu!"

• T message = pipeline.apply((T) "This is a log message.");
  

  I apply the final pipeline function to a sample input.
  Since this time I tested it with a String, I cast it as (T). But this method can now accept any type!"

  Shifu (smiling, eyes narrowing with pride):
  "You’ve taken the form beyond its scroll, Po. You have learned not just to use functions—but to respect their essence. This generic version... is the true Dragon Scroll of the Decorator."

  Modified Code by Po

• package com.javaonfly.designpatterns.decorator.fp;
  
  import java.time.LocalDateTime;
  import java.util.Arrays;
  import java.util.function.Function;
  
  public class Logger {  
      public <T> void decoratedLogMessage(Function<T, T>... loggers) {
          Function<T, T> pipeline= Arrays.stream(loggers).sequential().reduce(Function.identity(), Function::andThen);
          T message = pipeline.apply((T) "This is a log message.");
          System.out.println(message);
      }
  
      public static void main(String[] args){
          Logger logger = new Logger();
          Function<String, String> simpleLogger = message -> {
              System.out.println(message);
              return message;
          };
  
          Function<String, String> timestampLogger = message -> {
              String timestampedMessage =  "[" + System.currentTimeMillis() + "] " + message;
              return timestampedMessage;
          };
          Function<String, String> JadeLogger = message -> {
              String JadeLoggedMessage =  "[jadelog] " + message;
              return JadeLoggedMessage;
          };
     
          logger.decoratedLogMessage(simpleLogger, timestampLogger,JadeLogger);
      }
  }
  //Output
  This is a log message.
  [jadelog] [1748598136677] This is a log message.

• Wisdom Scroll: OOP vs Functional Decorator
  Feature
  OOP Decorator
  Functional Decorator
  Needs Class
  Yes
  No
  Uses Interface
  Yes
  Optional
  Composability
  Rigid
  Elegant
  Boilerplate
  High
  Minimal
  Flexibility
  Moderate
  High (thanks to lambdas)
  
  

Final Words from Master Shifu

"Po, the world of code is full of distractions—designs that look powerful but slow us down. A true Kung Fu developer learns to adapt. To decorate without weight. To enhance without inheritance. To flow with functions, not fight the structure."

Part 1- Kung Fu Code: Master Shifu Teaches Strategy Pattern to Po – the Functional Way!

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