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Using log analysis to drive experiments and win the AWS DeepRacer F1 ProAm Race

This is a guest post by Ray Goh, a tech executive at DBS Bank.  AWS DeepRacer is an autonomous 1/18th scale race car powered by reinforcement learning, and the AWS DeepRacer League is the world’s first global autonomous racing league. It’s a fun and easy way to get started with machine learning (ML), regardless of […]



This is a guest post by Ray Goh, a tech executive at DBS Bank. 

AWS DeepRacer is an autonomous 1/18th scale race car powered by reinforcement learning, and the AWS DeepRacer League is the world’s first global autonomous racing league. It’s a fun and easy way to get started with machine learning (ML), regardless of skill or background. For companies, it’s also a powerful platform to facilitate teaching ML to employees at the enterprise level.

As part of our digital transformation journey at DBS Bank, we’re taking innovative steps to future-proof our workforce. We’ve partnered with AWS to bring the AWS DeepRacer League to DBS to train over 3,000 employees in AI and ML by the end of 2020. Thanks to the AWS DeepRacer virtual simulation and training environment, our employees can upgrade their skills and pick up new knowledge, even when they aren’t physically in the office. The ability to run private races also allows us to create our own racing league, where our employees can put their newly learned skills to the test.

Winning the F1 ProAm Race in May 2020

As an individual racer, I’ve been active in the AWS DeepRacer League since 2019. In May 2020, racers from around the world had the unique opportunity to pit their ML skills against F1 professionals in the AWS DeepRacer F1 ProAm Race. We trained our models on a replica of the F1 Spanish Grand Prix track, and the top 10 racers from the month-long, head-to-head qualifying race faced off against F1 professional drivers Daniel Ricciardo and Tatiana Calderon in a Grand Prix-style race. Watch the AWS DeepRacer ProAm series here.

After a challenging month of racing, I emerged as the champion in the F1 ProAm Race, beating fellow racers and the pro F1 drivers to the checkered flag! Looking back now, I attribute my win to having performed many experiments throughout the month of racing. Those experiments allowed me to continuously tweak and improve my model leading up to the final race. Behind those experiments are ideas that arose from data-driven insights through log analysis.

What is log analysis?

Log analysis is using a Jupyter notebook to analyze and debug models based on log data generated from the AWS DeepRacer simulation and training environment. With snippets of Python code, you can plot and visualize your model’s training performance through various graphs and heatmaps. I created several unique visualizations that ultimately helped me train a model that was fast and stable enough to win the F1 ProAm Race.

Figure 1 Log analysis visualizations

In this post, I share some of the visualizations I created and show how you can use Amazon SageMaker to spin up a notebook instance to perform log analysis using DeepRacer model training data.

If you’re already familiar with opening notebooks in a JupyterLab notebook application, you can simply clone my log analysis repository and skip directly to the log analysis section.

Amazon SageMaker notebook instances

An Amazon SageMaker notebook instance is a managed ML compute instance running the Jupyter notebook application. Amazon SageMaker manages the creation of the instance and its related resources, so we can focus on analyzing the data collected during training without worrying about provisioning Amazon Elastic Compute Cloud (Amazon EC2) or storage resources directly.

Using an Amazon SageMaker notebook instance for log analysis

One of the greatest benefits of using an Amazon SageMaker notebook instance to perform AWS DeepRacer log analysis is that Amazon SageMaker automatically installs Anaconda packages and libraries for common deep learning platforms on our behalf, including TensorFlow deep learning libraries. It also automatically attaches an ML storage volume to our notebook instance, which we can use as a persistent working storage to perform log analysis and retain our analysis artifacts.

Creating a notebook instance

To get started, create a notebook instance on the Amazon SageMaker console.

  1. On the Amazon SageMaker console, under Notebook, choose Notebook instances.
  2. Choose Create notebook instance.

  1. For Notebook instance name, enter a name (for example, DeepRacer-Log-Analysis).
  2. For Notebook instance type¸ choose your instance.

For AWS DeepRacer log analysis, the smallest instance type (ml.t2.medium) is usually sufficient.

  1. For Volume size in GB, enter your storage volume size. For this post, we enter 5.

When the notebook instance shows an InService status, we can open JupyterLab, the IDE for Jupyter notebooks.

  1. Locate your notebook instance and choose Open JupyterLab.

Cloning the log analysis repo from JupyterLab

From the JupyterLab IDE, we can easily clone a Git repository to use log analysis notebooks shared by the community. For example, I can clone my log analysis repository in seconds, using as the Clone URI.

After cloning the repository, we should see it appear in the folder structure on the left side of the JupyterLab IDE.

Downloading logs from the AWS DeepRacer console

To prepare the data that we want to analyze, we have to download our model training logs from the AWS DeepRacer console.

  1. On the AWS DeepRacer console, under Reinforcement learning, choose Your models.
  2. Choose the model to analyze.
  3. In the Training section, under Resources, choose Download Logs.

This downloads the training log files, which are packaged in a .tar.gz file.

Extracting the required log files for analysis

In this step, we complete the final configurations.

  1. Extract the RoboMaker and Amazon SageMaker log files from the .tar.gz package (found in the logs/training/ subdirectory).

  1. Upload the two log files into the /deepracer-log-analysis/logs folder in the JupyterLab IDE.

We’re now ready to open up our log analysis notebook to work its magic!

  1. Navigate to the /deepracer-log-analysis folder on the left side of the IDE and choose the .ipynb file to open the notebook.
  2. When opening the notebook, you may be prompted to provide a kernel. Choose a kernel that uses Python 3, such as conda_tensorflow_p36.

  1. Wait until the kernel status changes from Starting to Idle.
  2. Edit the notebook to specify the path and names of the two log files that we just uploaded.

To perform our visualizations, we use the simulation trace data from the RoboMaker log file and policy update data from the Amazon SageMaker log file. We parse the data in the notebook using pandas dataframes, which are two-dimensional labeled data structures like spreadsheets or SQL tables.

For the RoboMaker log file, we aggregate important information, such as minimum, maximum, and average progress and lap completion ratios for each iteration of training episodes.

For the Amazon SageMaker log file, we calculate the average entropy per epoch in each policy update iteration.

Performing visualizations

We can now run the notebook by choosing Run and Run All Cells in JupyterLab. My log analysis notebook contains numerous markdown descriptions and comments to explain what each cell does. In this section, I highlight some of the visualizations from that notebook and explain some of the thought processes behind them.

Visualizing the performance envelope of the model

A common question asked by beginners of AWS DeepRacer is, “If two models are trained for the same amount of time using the same reward function and hyperparameters, why do they have different lap times when I evaluate them?”

The following visualization is a great way to explain it; it shows the frequency of performance to lap time in seconds.

I use this to illustrate the performance envelope of my model. We can show the relative probability of the model achieving various lap times by plotting a histogram of lap times achieved by the model during training. We can also work out statistically the average and best-case lap times that we can expect from the model. I’ve noticed that the lap times of the model during training resembles a normal distribution, so I use the -2 and -3 Std Dev markers to show the potential best-case lap times for the model, albeit with just 2.275% (-2 SD) and 0.135% (-3 SD) chance of occurring respectively. By understanding the likelihood of the model achieving a given lap time and comparing that to leaderboard times, I can gauge if I should continue cloning and tweaking the model, or abandon it and start fresh with a different approach.

Identifying potential model checkpoints for race submission

When training many different models for a race, racers commonly ask, “Which model would give me the highest chance of winning a virtual race?”

To answer that question, I plot the top quartile (p25) lap times vs. iterations from the training data, which identifies potential models for race submission. This scatter plot also allows me to identify potential trade-offs between speed (dots with very fast lap times) and stability (dense cluster of dots for a particular iteration). From the following diagram, I would choose models from the three highlighted iterations for race submission.

Identifying convergence and gauging consistency

As racers gain experience with model training, they start paying attention to convergence in their models. Simply put, convergence in the AWS DeepRacer context is when a model is performing close to its best (in terms of average lap progress), and further training may harm its performance or make it overfit, such that it only does well for that track in a very specific simulation environment, but not in other tracks or in a physical AWS DeepRacer car. That begs the following questions: “How do I tell when the model has converged?” and “How consistent is my model after it has converged?”

To aid in visualizing convergence, I overlay the entropy information from the Amazon SageMaker policy training logs over the usual plots for rewards and progress.

Entropy is a measure of the amount of randomness in our reinforcement learning neural network. At the beginning of model training, entropy is high, because our neural network is updated mostly based on random actions as the car explores the track.

Over time, with more experiences gained from actions and rewards at various parts of the track, the car starts to exploit this information and takes less random actions.

The thinking behind this is that, as rewards and progress increase, the entropy value should decrease. When rewards and progress plateau, the entropy loss should also flatten out. Therefore, I use entropy as an additional indicator for convergence.

To gauge the consistency of my model, I also plot the percentage of lap completions per iteration during training. When the model is capable of completing laps, the percentage of completed laps should creep up in subsequent iterations, until around the point of convergence, when the percentage value should plateau too. See the following plot.

The model training process is probabilistic because the reinforcement learning agent incorporates entropy to explore the environment. To smooth out the effects of the probabilistic model in my visualization, I use a simple moving average over three iterations for each of my plotted metrics.

Identifying inefficiencies in driving behavior

When racers have a competitive model, they may start to wonder, “Are there sections of the track where the car is driving inefficiently? What are the sections where I can encourage the car to speed up?”

In pursuit of answering these questions, I designed a visualization that shows the average speed and steering angle of the car measured at every waypoint along the track. This allows me to see how the model is negotiating the track, because from this plot, you can see the rate at which the model is speeding up or slowing down as it travels through the waypoints. The following visualization shows the deviation of the optimal racing line (orange) from the track centerline (blue).

You can also see how the model adjusts its steering angle as it negotiates turns. What I love about the following visualization is that it allows me to see clearly at which point after a long straight the model starts to brake before entering into a turn. It also helps me visualize if a model is accelerating quickly enough upon exiting a turn.

Identifying track sections to adjust actions and rewards

Although speed is the primary performance criteria in a time trial race, stability is also important in an object avoidance or head-to-head race. Because time penalties for going off-track impact race position, it’s very important to find the right balance between speed and stability. Even if the model can negotiate the track well, top racers are also asking, “Is the car over- or under-steering at any of the turns? Which turn should I focus on optimizing in subsequent experiments?”

By plotting a heatmap of rewards over the track, you can easily see how consistently we reward the model at various parts of the track. A thin band in the heatmap reflects very consistent rewards, while a sparse scattering of dots brings attention to the parts of the track where the model has trouble getting rewards. For my reward function, this usually highlights the turns at which the model is over- or under-steering.

For example, in the highlighted parts of the preceding plot, the model isn’t consistently going around those turns according to the racing line that I’m rewarding for. It’s actually over-steering as it exits Turn 3 (around waypoint 62), and under-steering around the other two highlighted turns. Tweaking the action space may help (in the case of under-steering, lowering the speed at high steering angles). Interestingly, the lap completion rate of the model can increase substantially with such minor tweaks, without sacrificing lap times!

Experiment, Experiment, Experiment

For the F1 ProAm Race that in May 2020, I planned to do two experiments per day (at least 60 experiments total) to try out different reward strategies and racing lines. I could iterate quickly while focusing on incremental improvements by using log analysis to surface insights from the training data.

For example, the following plot helped me answer the question “Is the car going to go as fast as possible through the entire lap?” by showing where the car uses 0-degree and highest speeds.

Cleaning up

To save on ML compute costs, when you’re done with log analysis, you can stop the notebook instance without deleting it. The notebook, data, and log files are still retained as long as you don’t delete the notebook instance. A stopped instance still incurs cost for the provisioned ML storage. But you can always restart the instance later to continue working on the notebook.

When you no longer need the notebook or data, you can permanently delete the instance, which also deletes the attached ML storage volume, so that you no longer incur its related ML storage cost.

For pricing details for Amazon SageMaker notebook instances, see Amazon SageMaker Pricing.


The visualizations I shared with you in this post helped me win the May 2020 F1 ProAm Race against other top racers and F1 pros, so it’s my hope that by sharing these ideas with the community, others can benefit and learn from them too.

Together as a community of practice, we can help to accelerate learning for everyone and raise the bar for the AI/ML community in general!

You can start training your own model and improve it through log analysis by signing in to the AWS DeepRacer console.

About the Author

Ray Goh is a Tech executive who leads Agile Teams in the delivery of FX Trading & Digital Solutions at DBS Bank. He is a passionate Cloud advocate with deep interest in Voice and Serverless technology, and has 8 AWS Certifications under his belt. He is also active in the DeepRacer (a Machine Learning autonomous model car) community. Obsessed with home automation, he owns close to 20 Alexa-enabled devices at home and in the car.



Things to Know about Free Form Templates

A single file that includes numerous supporting files is commonly known as a form template. Some files will define or show the controls to appear on the free form templates or design. The collections of these supporting files or templates are also called form files. While designing free form templates, users should be able to […]

The post Things to Know about Free Form Templates appeared first on 1redDrop.



A single file that includes numerous supporting files is commonly known as a form template. Some files will define or show the controls to appear on the free form templates or design. The collections of these supporting files or templates are also called form files. While designing free form templates, users should be able to view and also work with the form files. 

It will create a new free form template by copying and storing those files within a folder. A form template (.XSN) file designing or creation of a single file will include various supporting files. Users may fill out the online form by accessing the .XML form file, which is a form template.

Designing Free Form Templates

There are numerous processes that define free form template design, and are as follows:

  • Designing the form’s appearance – the instructional text, labels, and controls
  • Controls will assist with user interaction behavior on the form template. You can design a specific section to appear or disappear when the user chooses a particular option
  • Whether the form template may include some additional views. For a permit application form design, for example, you have to provide different views for each person. One view especially for the electrical contractor, next for the receiving agent, and finally, the investigator. He or she will deny or approve the permit application
  • Next, you need to know how & where to store the form data. Designing free from templates will allow users to submit their data within the database either online or direct access. If not, they can also store the same in any specific shared folder
  • It is essential to design the other elements, colors, and fonts within the form template
  • Users must be able to personalize the form. Allowing users to include various rows within the optional section, repeating section, or a repeating table
  • Users should receive a notification when they forget to input a mandatory field or make mistakes within the form
  • After completing the free form templates design, you can publish the same online using a .XSN file format

Club Signup Form

A simple registration form can help your Club Signup Form creation process go smoother. This signup form could be an ideal solution for a new club membership registration for any organization or club.

Application Form

Application form templates are much easier to use & set-up to streamline your application process. You can customize this online form and utilize the same for numerous applications. Make use of this application form as a job application form, volunteer applications, contest entries, or high school scholarship applications. It is an ideal solution for scholarship programs, nonprofit organizations, business owners, and many such users and use cases.

Scheduling Form

Scheduling form templates are handy and can be used for numerous appointment booking requirements. A scheduling form is also utilized for various appointment scheduling or online reservations and booking purposes. Regardless of your business requirement, it is easy to customize the form template.

Concept Testing Survey

While testing a new design or concept, it is essential to gather the responses quickly. Freeform templates for a concept testing survey make it much easier to gather product feedback and reach the target audience. It is essential to conduct market research while planning to release a new product. A mobile-friendly form will allow you to utilize the survey questions for collecting the product’s consumer input quickly.

Credit Card Order Form

It is not always a complex process to provide an online credit card payment form for the customers. This form template will allow you to access numerous services or products for collecting card payment information. You can utilize this yet-another endless and simple payment form.

Employment Application Form

The employment application form for recruitment will assist the HR team to gather the required information from candidates. During the interview or application process, you can easily remove any expensive follow-ups. Some of the fields are contact information, employment history, useful information, etc. as well as an outline of the job description, consent for background checks, military service record, anticipated start date, any special skills, and many more. It is optional to enable notifications for the form owners to receive an alert or email when a new employment application is submitted.


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Are Chatbots Vulnerable? Best Practices to Ensure Chatbots Security



Rebecca James
credit IT Security Guru

A simple answer is a Yes! Chatbots are vulnerable. Some specific threats and vulnerabilities risk chatbots security and prove them a wrong choice for usage. With the advancement in technology, hackers can now easily target the hidden infrastructure of a chatbot.

The chatbot’s framework has an opportunity for the attackers ready to inject the malicious codes or commands that might unlock the secured data of the customers and your business. However, the extent of the attack’s complexity and success might depend on the messaging platform’s security.

Are you thinking about how chatbots are being exposed to attacks? Well! Hackers are now highly advanced. They attack the chatbots in two ways, i.e., either by social engineering attack or by technical attacks.

  • An evil bot can impersonate a legal user by using backup data of the possibly targeted victims by social engineering attack. All such data is collected from various sources like the dark web and social media platforms. Sometimes they use both sources to gain access to some other user’s data by a bot providing such services.
  • The second attack is technical. Here also attackers can turn themself into evil bots who exchange messages with the other bots. The purpose is to look for some vulnerabilities in the target’s profile that can be later exploited. It can eventually lead to the compromise of the entire framework that protects the data and can ultimately lead to data theft.

To ensure chatbots security, the bot creators must ensure that all the security processes are in place and are responsible for restoring the architecture. The data flow via the chatbot system should also be encrypted both in transit and rest.

To further aid you in chatbot security, this article discusses five best practices to ensure chatbots security. So, let’s read on.

The following mentioned below are some of the best practices to ensure the security of chatbots.

It’s always feared that data in transit can be spoofed or tampered with the sophistication of cybercriminals’ technology and smartness. It’s essential to implement end-to-end encryption to ensure that your entire conversation remains secured. It means that by encryption, you can prevent any third person other than the sender and the receiver from peeping into your messages.

Encryption importance can’t be neglected in the cyber world, and undoubtedly the chatbot designers are adapting this method to make sure that their chatbot security is right on the point. For more robust encryption, consider using business VPNs that encrypt your internet traffic and messages. With a VPN, you can also prevent the threats and vulnerabilities associated with chatbots.

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4. Chatbot Conference Online

Moreover, it’s a crucial feature of other chat services like WhatsApp and other giant tech developers. They are anxious to guarantee security via encryption even when there’s strict surveillance by the government. Such encryption is to fulfill the legal principles of the GDPR that says that companies should adopt measures to encrypt the users’ data.

User identity authentication is a process that verifies if the user is having secure and valid credentials like the username and password. The login credentials are exchanged for having a secure authentication token used during the complete user session. If you haven’t, then you should try out this method for boosting user security.

Authentication timeouts are another way to ensure your chatbots security. This method is more common in banks as the token can be used for the predetermined time.

Moreover, two-factor authentication is yet another method to prove user identity. Users are asked to verify identity either by a text message or email, depending on the way they’ve chosen. It also helps in the authorization process as it permits access to the right person and ensures that information isn’t mishandled or breached.

The self-destructive message features open another way for enhancing chatbot security. This option comes in handy when the user provides their personally identifiable information. Such information can pose a serious threat to user privacy and should be destroyed or deleted within a set period. This method is handier when you’re associated with backing or any other financial chatbots.

By using secure protocols, you can also ensure chatbots security. Every security system, by default, has the HTTPS protocol installed in it. If you aren’t an IT specialist, you can also identify it when you view the search bar’s URL. As long as your data is being transferred via HTTPS protocol and encrypted connections, TLS and SSL, your data is secured from vulnerabilities and different types of cyber-attacks.

Thus, make sure to use secure protocols for enhanced security. Remember that when Chatbots are new, the coding and system used to protect it is the same as the existing HIMs. They interconnect with their security systems and have more than one encryption layer to protect their users’ security.

Do you know what the most significant security vulnerability that’s challenging to combat is? Wondering? Well! It’s none other than human error. User behavior must be resolved using commercial applications because they might continue to believe that the systems are flawed.

No doubt that an unprecedented number of users label the significance of digital security, but still, humans are the most vulnerable in the system. Chatbot security continues to be a real big problem until the problem of user errors comes to an end. And this needs education on various forms of digital technology, including chatbots.

Here the customers aren’t the ones who are to be blamed. Like customers, employees can make a mistake, and they do make most of the time. To prevent this, the chatbot developers should form a defined strategy, including the IT experts, and train them on the system’s safe use. Doing so enhances the team’s skillset and allows them to engage with the chatbot system confidently.

However, clients can’t be educated like the employees. But at least you can provide them a detailed road map of securely interacting with the system. It might involve other professionals who can successfully engage customers and educate them on the right way to interact with the chatbots.

Several emerging technologies are keen to play a vital role in protecting the chatbots against threats and vulnerabilities in the upcoming time, among all the most potent method behavior analytics and Artificial Intelligence developments.

  • User Behavioral Analytics: It’s a process that uses applications to study the patterns of user behavior. It enables them to implement complex algorithms and statistical analysis to detect any abnormal behavior that possibly represents a security threat. Analytical tools are quite common and powerful; thus, this methodology can become a fundamental component of the chatbot system.
  • Developments in AI: Artificial technology is a two-end sword that offers benefits and threats simultaneously. But, as AI is predicted to fulfill its potential, it will provide an extra security level to the systems. It is mainly because of its ability to wipe a large amount of data for abnormalities that recognizes security breaches and threats.

The Bottom Line

Security concerns have always been there with new technologies and bring new threats and vulnerabilities with them. Although chatbots are an emerging technology, the security practices that stand behind them are present for a long time and are effective. Chatbots are the innovative development of the current era, and emerging technologies like AI will transform the way businesses might interact with the customers and ensure their security.


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Best Technology Stacks For Mobile App Development



What’s the Best Tech Stack for Mobile App Development? Read To Know

Which is the Best Tech Stack for Mobile Application Development? Kotlin, React Native, Ionic, Xamarin, Objective-C, Swift, JAVA… Which One?

Image Source: Google

Technology Stack for smartphones is like what blood is for the human body. Without a technology stack, it is hard even to imagine smartphones. Having a smartphone in uncountable hands is rising exponentially. For tech pundits, this is one unmissable aspect of our digital experience wherein tech stack is as critical as ROI.

The riveting experience for a successful mobile app predominantly depends on technology stacks.

The unbiased selection of mobile apps development language facilitates developers to build smooth, functional, efficient apps. They help businesses tone down the costs, focus on revenue-generation opportunities. Most importantly, it provides customers with jaw-dropping amazement, giving a reason to have it installed on the indispensable gadget in present times.

In today’s time, when there are over 5 million apps globally, and by all conscience, these are whopping no.s and going to push the smartphone industry further. But now you could see mobile app development every ‘nook and corner.’ But the fact is not who provides what but understanding the behavioural pattern of users.

So the pertinent question is, which is the ideal tech stack to use for mobile app development?

In native mobile app development, all toolkits, mobile apps development language, and the SDK are supported and provided by operating system vendors. Native app development thus allows developers to build apps compatible with specific OS environments; it is suitable for device-specific hardware and software. Hence it renders optimized performance using the latest technology. However, since Android & iOS imparts — — a unique platform for development, businesses have to develop multiple mobile apps for each platform.

1. Waz

2. Pokemon Go

3. Lyft

1.Java: The popularity of JAVA still makes it one of the official programming languages for android app development until the introduction of Kotlin. Java itself is at the core of the Android OS. Many of us even see the logo of Java when the device reboots. However, contradictions with Oracle (which owns the license to Java) made Google shift to open-source Java SDK for versions starting from Android 7.0 Nougat

2.Kotlin: According to Google I/O conference in 2019- Kotlin is the officially supported language for Android app development. It is entirely based on Java but has a few additions which make it simpler and easier to work.

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It’s my gut feeling like other developers to say that Kotlin is simply better. It has a leaner, more straightforward and concise code than open-cell Java, and several other advantages about handling null-pointer exceptions and more productive coding.

HERE’S A Programming Illustration Defining the CONCISENESS OF KOTLIN CODE

public class Address {

private String street;

private int streetNumber;

private String postCode;

private String city;

private Country country;

public Address(String street, int streetNumber, String postCode, String city, Country country) {

this.street = street;

this.streetNumber = streetNumber;

this.postCode = postCode; = city; = country;



public boolean equals(Object o) {

if (this == o) return true;

if (o == null || getClass() != o.getClass()) return false;

Address address = (Address) o;

if (streetNumber != address.streetNumber) return false;

if (!street.equals(address.street)) return false;

if (!postCode.equals(address.postCode)) return false;

if (!city.equals( return false;

return country ==;



public int hashCode() {

int result = street.hashCode();

result = 31 * result + streetNumber;

result = 31 * result + postCode.hashCode();

result = 31 * result + city.hashCode();

result = 31 * result + (country != null ? country.hashCode() : 0);

return result;



public String toString() {

return “Address{“ +

“street=’” + street + ‘\’’ +

“, streetNumber=” + streetNumber +

“, postCode=’” + postCode + ‘\’’ +

“, city=’” + city + ‘\’’ +

“, country=” + country +



public String getStreet() {

return street;


public void setStreet(String street) {

this.street = street;


public int getStreetNumber() {

return streetNumber;


public void setStreetNumber(int streetNumber) {

this.streetNumber = streetNumber;


public String getPostCode() {

return postCode;


public void setPostCode(String postCode) {

this.postCode = postCode;


public String getCity() {

return city;


public void setCity(String city) { = city;


public Country getCountry() {

return country;


public void setCountry(Country country) { = country;



class Address(street:String, streetNumber:Int, postCode:String, city:String, country:Country) {

var street: String

var streetNumber:Int = 0

var postCode:String

var city: String

var country:Country


this.street = street

this.streetNumber = streetNumber

this.postCode = postCode = city = country


public override fun equals(o:Any):Boolean {

if (this === o) return true

if (o == null || javaClass != o.javaClass) return false

Val address = o as Address

if (streetNumber != address.streetNumber) return false

if (street != address.street) return false

if (postCode != address.postCode) return false

if (city != return false

return country ===


public override fun hashCode():Int {

val result = street.hashCode()

result = 31 * result + streetNumber

result = 31 * result + postCode.hashCode()

result = 31 * result + city.hashCode()

result = 31 * result + (if (country != null) country.hashCode() else 0)

return result


public override fun toString():String {

return (“Address{“ +

“street=’” + street + ‘\’’.toString() +

“, streetNumber=” + streetNumber +

“, postCode=’” + postCode + ‘\’’.toString() +

“, city=’” + city + ‘\’’.toString() +

“, country=” + country +




I’d say KOTLIN IS THE BEST FIND FOR ANDROID APP DEVELOPMENT.Google has dug deeper with some plans ahead since announcing it as an official language. Moreover, it signals Google’s first steps in moving away from the Java ecosystem, which is imminent, considering its recent adventures with Flutter and the upcoming Fuchsia OS.

Objective C is the same for iOS what Java is for Android. Objective-C, a superset of the C programming language( with objective -oriented capabilities and dynamic run time) initially used to build the core of iOS operating system across the Apple devices. However, Apple soon started using swift, which diminishes the importance of Objective -C in comparison to previous compilations.

Apple introduced Swift as an alternative to Objective-C in late 2015, and it has since been continued to be the primary language for iOS app development.Swift is more functional than Objective-C, less prone to errors, dynamic libraries help reduce the size and app without ever compromising performance.

Now, you would remember the comparison we’ve done with Java and kotlin. In iOS, objective-C is much older than swift with much more complicated syntax. Giving cringeworthy feel to beginners to get started with Objective-C.

Image Source: Google


NSMutableArray * array =[[NSMutableArray alloc] init];


var array =[Int]()


In cross-platform app development, developers build a single mobile app that can be used on multiple OS platforms. It is made possible by creating an app with a shared common codebase, adapted to various platforms.

Image Source: Google

Popular Cross-platform apps:

  1. Instagram
  2. Skype
  3. LinkedIN

React Native is a mobile app development framework based on JavaScript. It is used and supported by one of the biggest social media platforms- Facebook. In cross-platform apps built using React Native, the application logic is coded in JavaScript, whereas its UI is entirely native. This blog about building a React Native app is worth reading if you want to know why its stakes are higher.

Xamarin is a Microsoft-supported cross-platform mobile app development tool that uses the C# programming language. Using Xamarin, developers can build mobile apps for multiple platforms, sharing over 90% of the same code.

TypeScript is a superset of JavaScript, and is a statically-typed programming language supported by Microsoft. TypeScript can be used along with the React Native framework to make full use of its error detection features when writing code for react components.

In Hybrid mobile app development, developers build web apps using HTML, CSS & JavaScript and then wrap the code in a native shell. It allows the app to be deployed as a regular app, with functionality at a level between a fully native app and a website rendered(web browser).

Image Source: Google
  1. Untappd
  2. Amazon App Store
  3. Evernote

Apache Cordova is an open-source hybrid mobile app development framework that uses JavaScript for logic operations and while HTML5 & CSS3 for rendering. PhoneGap is a commercialized, free, and open-source distribution of Apache Cordova owned by Adobe. The PhoneGap platform was developed to deliver non-proprietary, free, and open-source app development solutions powered by the web.

Ionic is a hybrid app development framework based on AngularJS. Similar to other hybrid platforms, it uses HTML, CSS & JavaScript to build mobile apps. Ionic is primarily focused on the front-end UI experience and integrates well with frameworks such as Angular, Vue, and ReactJS.

To summarize, there are 3 types of mobile apps- Native mobile apps, Cross-platform mobile apps, and Hybrid mobile apps; each offers unique technologies, frameworks, and tools of their own. I have enlisted here the best mobile app technology stacks you could use for mobile app development.

The technologies, tools, and frameworks mentioned here are used in some of the most successful apps. With support from an expert, a well-established mobile app development company, that may give much-needed impetus in the dynamic mobile app development world.


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