Template Method Design Pattern Tutorial
Welcome to my Template Method Design Pattern Tutorial. It is an extremely easy design pattern to understand and use.
With this pattern, you define a method (algorithm) in an abstract class. It contains both abstract methods and non-abstract methods. The subclasses that extend this abstract class then override those methods that don’t make sense for them to use in the default way.
It may sound complicated, but it definitely isn’t. It is also extremely useful. Look at the code after the video to get a complete understanding quickly.
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Code from the Video
ITALIANHOAGIE.JAVA
public class ItalianHoagie extends Hoagie{
String[] meatUsed = { "Salami", "Pepperoni", "Capicola Ham" };
String[] cheeseUsed = { "Provolone" };
String[] veggiesUsed = { "Lettuce", "Tomatoes", "Onions", "Sweet Peppers" };
String[] condimentsUsed = { "Oil", "Vinegar" };
public void addMeat(){
System.out.print("Adding the Meat: ");
for (String meat : meatUsed){
System.out.print(meat + " ");
}
}
public void addCheese(){
System.out.print("Adding the Cheese: ");
for (String cheese : cheeseUsed){
System.out.print(cheese + " ");
}
}
public void addVegetables(){
System.out.print("Adding the Vegetables: ");
for (String vegetable : veggiesUsed){
System.out.print(vegetable + " ");
}
}
public void addCondiments(){
System.out.print("Adding the Condiments: ");
for (String condiment : condimentsUsed){
System.out.print(condiment + " ");
}
}
}
/*
public void makeSandwich(){
cutBun();
addMeat();
addCheese();
addVegetables();
addCondiments();
wrapTheHoagie();
}
public void cutBun(){
System.out.println("The Hoagie is Cut");
}
public void addMeat(){
System.out.println("Add Salami, Pepperoni and Capicola ham");
}
public void addCheese(){
System.out.println("Add Provolone");
}
public void addVegetables(){
System.out.println("Add Lettuce, Tomatoes, Onions and Sweet Peppers");
}
public void addCondiments(){
System.out.println("Add Oil and Vinegar");
}
public void wrapTheHoagie(){
System.out.println("Wrap the Hoagie");
}
}
*/
HOAGIE.JAVA
// A Template Method Pattern contains a method that provides
// the steps of the algorithm. It allows subclasses to override
// some of the methods
public abstract class Hoagie {
boolean afterFirstCondiment = false;
// This is the Template Method
// Declare this method final to keep subclasses from
// changing the algorithm
final void makeSandwich(){
cutBun();
if(customerWantsMeat()){
addMeat();
// Here to handle new lines for spacing
afterFirstCondiment = true;
}
if(customerWantsCheese()){
if(afterFirstCondiment) { System.out.print("\n"); }
addCheese();
afterFirstCondiment = true;
}
if(customerWantsVegetables()){
if(afterFirstCondiment) { System.out.print("\n"); }
addVegetables();
afterFirstCondiment = true;
}
if(customerWantsCondiments()){
if(afterFirstCondiment) { System.out.print("\n"); }
addCondiments();
afterFirstCondiment = true;
}
wrapTheHoagie();
}
// These methods must be overridden by the extending subclasses
abstract void addMeat();
abstract void addCheese();
abstract void addVegetables();
abstract void addCondiments();
public void cutBun(){
System.out.println("The Hoagie is Cut");
}
// These are called hooks
// If the user wants to override these they can
// Use abstract methods when you want to force the user
// to override and use a hook when you want it to be optional
boolean customerWantsMeat() { return true; }
boolean customerWantsCheese() { return true; }
boolean customerWantsVegetables() { return true; }
boolean customerWantsCondiments() { return true; }
public void wrapTheHoagie(){
System.out.println("\nWrap the Hoagie");
}
public void afterFirstCondiment(){
System.out.println("\n");
}
}
VEGGIEHOAGIE.JAVA
public class VeggieHoagie extends Hoagie{
String[] veggiesUsed = { "Lettuce", "Tomatoes", "Onions", "Sweet Peppers" };
String[] condimentsUsed = { "Oil", "Vinegar" };
boolean customerWantsMeat() { return false; }
boolean customerWantsCheese() { return false; }
public void addVegetables(){
System.out.print("Adding the Vegetables: ");
for (String vegetable : veggiesUsed){
System.out.print(vegetable + " ");
}
}
public void addCondiments(){
System.out.print("Adding the Condiments: ");
for (String condiment : condimentsUsed){
System.out.print(condiment + " ");
}
}
void addMeat() {}
void addCheese() {}
}
SANDWICHSCULPTOR.JAVA
public class SandwichSculptor {
public static void main(String[] args){
ItalianHoagie cust12Hoagie = new ItalianHoagie();
cust12Hoagie.makeSandwich();
System.out.println();
VeggieHoagie cust13Hoagie = new VeggieHoagie();
cust13Hoagie.makeSandwich();
}
}
Please can you make a video series dedicated to Java FX 2.2 ?
EX: How to create an program that stores phone models(every model with their picture) inside a database. And pack the app inside a jar or installer for distribution.
Thank you for the request and I’ll definitely cover Java FX. By the end of this series I will cover pretty much everything there is to know about java and good programming
excellent work..keep it up..please include if possible UML diagrams also..:)
Thank you 🙂 I wish I would have used UML but at the time I made a judgement call to not require people to understand UML to follow along. I then made a UML tutorial if that may help.
Hey Derek!
I’m not getting tired of seeing your videos, I’m really learning a lot!! I’m actually studying computer sciences and this is helping me like a lot! If there’s anything i could do for you please let me know! You’re simply incredible, thanks for your videos 🙂
Thank you 🙂 I’m just happy that the videos are helping. I don’t require anything else.