Design Pattern: Template Method Pattern in Java

Template Method pattern is used to implement a process where subclasses can change some steps of the parent.

This article demonstrates Template Method pattern implementations in Java. Check the following examples.

Examples

Here are examples of Templete Method Pattern implementation in Java-

Example #1: Transport Construction Template

Let’s consider an example of a transport builder.

Transport Abstract Class

// Transport.java

package com.bigboxcode.designpattern.templatemethod.transport;

public abstract class Transport {
    abstract void createBody();

    abstract void addEngine();

    abstract void addWheel();

    // Required only for Plane
    abstract void addWing();

    private void addSeat() {
        // Add seats to the vehicle

        // Adding seats are same for all transports so same functions for all

        System.out.println("Adding seats");
    }

    private void paint() {
        System.out.println("Painting");
    }

    public void build() {
        createBody();

        addEngine();

        addWheel();

        addWing();

        addSeat();

        paint();
    }
}

Car Transport Class

// Car.java

package com.bigboxcode.designpattern.templatemethod.transport;

public class Car extends Transport {
    @Override
    void createBody() {
        System.out.println("Creating Car Body");
    }

    @Override
    void addEngine() {
        System.out.println("Adding Engine to Car");
    }

    @Override
    void addWheel() {
        System.out.println("Adding 4 Wheels to Car");
    }

    @Override
    void addWing() {
        // Not required for Car
    }
}

Bike Transport Class

// Bike.java

package com.bigboxcode.designpattern.templatemethod.transport;

public class Bike extends Transport {
    @Override
    void createBody() {
        System.out.println("Creating Bike Body");
    }

    @Override
    void addEngine() {
        System.out.println("Adding Engine to Bike");
    }

    @Override
    void addWheel() {
        System.out.println("Adding 2 Wheels to Bike");
    }

    @Override
    void addWing() {
        // Not required for Bike
    }
}

Plane Transport Class

// Plane.java

package com.bigboxcode.designpattern.templatemethod.transport;

public class Plane  extends Transport {
    @Override
    void createBody() {
        System.out.println("Creating Plane Body");
    }

    @Override
    void addEngine() {
        System.out.println("Adding Engine to Plane");
    }

    @Override
    void addWheel() {
        System.out.println("Adding 3 Wheels to Plane");
    }

    @Override
    void addWing() {
        System.out.println("Adding Wings Plane");
    }
}

Train Transport Class

// Train.java

package com.bigboxcode.designpattern.templatemethod.transport;

public class Train extends Transport {
    @Override
    void createBody() {
        System.out.println("Creating Train Body");
    }

    @Override
    void addEngine() {
        System.out.println("Adding Engine to Train");
    }

    @Override
    void addWheel() {
        System.out.println("Adding Wheels to Train");
    }

    @Override
    void addWing() {
        // Not required for Train
    }
}

Demo

package com.bigboxcode.designpattern.templatemethod.transport;

public class Demo {
    public static void main(String[] args) {

        Transport car = new Car();
        car.build();

        Transport plane = new Plane();
        plane.build();
    }
}

Output

Creating Car Body
Adding Engine to Car
Adding 4 Wheels to Car
Adding seats
Painting


Creating Plane Body
Adding Engine to Plane
Adding 3 Wheels to Plane
Adding Wings Plane
Adding seats
Painting

Source Code

Use the following link to get the source code:

Example	Source Code Link
Example #1: Transport Builder	GitHub

Other Code Implementations

Use the following links to check Template Method pattern implementation in other programming languages.