Pro Programming

#include <bits/stdc++.h>

#define N 5

using namespace std;

int after_rev(vector<int> v)

{

    int mini = 0, count = 0;

    for (int i = 0; i < v.size(); i++) {

        count += v[i];

        if (count > 0)

            count = 0;

        if (mini > count)

            mini = count;

    }

    return mini;

}

void print(int arr[N])

{

    int sum = 0;

    for (int i = 0; i < N; i += 2)

        sum += arr[i];

    vector<int> v1, v2;

    for (int i = 0; i + 1 < N; i += 2)

        v1.push_back(arr[i + 1] - arr[i]);

    for (int i = 1; i + 1 < N; i += 2)

        v2.push_back(arr[i] - arr[i + 1]);

    int change = min(after_rev(v1),

                     after_rev(v2));

    if (change < 0)

        sum += change;

    cout << sum << endl;

}

int main()

{

    int arr[N] = { 0, 1, 4, 3 };

    print(arr);

    return 0;

}

If you are a newbie in machine learning you may have thought that what programming language should I learn? Nowadays different peoples are working with different programming languages but among these many popular high-level programming languages, which one is the best for machine learning? 

Machine Learning is one of the fastest-growing fields which has witnessed an exponential growth in the technical world. There is no best language for machine learning it depends on what you want to build, To work in this field, you just need to learn only one particular programming language very well based on your own comfort, project requirements, and predilections. Just explore some of these mostly used languages and pick up one of your choices, you don’t need to take anyone’s recommendation. 

1. Python

Python leads all the other languages with more than 60% of machine learning developers are using and prioritising it for development because python is easy to learn. Scalable and open source. Python has many awesome visualization packages and useful core libraries like Numpy, scipy, pandas, matplotlib, seaborn, sklearn which really makes your work very easy and empower the machines to learn. 
 

• Numpy: Numeric Python or Numpy is a Linear Algebra Library for Python with powerful data structures for efficient computation of multi-dimensional arrays and matrices.
• Pandas: It is the most popular Python library which provides highly optimized performance for data analysis.
• Matplotlib: It is a popular python plotting library used for creating basic graphs like line charts, bar charts, histograms and many more.
• Seaborn: Provides a high-level interface for creating attractive graphs
• sci-kit Learn: It is used for data mining and data analysis which implements a wide-range of machine-learning algorithms like classification, regression and clustering algorithms including support vector machines, random forests, gradient boosting, k-means .

2. Java 

This programming language is the “Jack of all the trade” and continues to dominate over in the ML industry also. Java provides many good environments like Weka, Knime, RapidMiner, Elka which used to perform machine learning tasks using graphical user interfaces. 

• Weka: It is a free, portable library which primarily used for data mining, data analysis, and predictive modelling and best used for machine learning algorithms. it is easy to use with the graphical interface and supports several standard data mining tasks, including data preprocessing, classification, clustering, and feature selection.
• JavaML: A Java API with simple and easy interfaces to implement the collection of machine learning and data mining algorithms in Java with clearly written and properly documented implementation of algorithms.
• Deeplearning4j: It is an innovative open-source distributed deep learning library which provides a computing framework with wide support for machine learning algorithms. This library is extremely useful for identifying patterns, sentiment, sound and text and is designed especially for business environments.
• ELKI: It is a unique open-source data mining framework which mainly focused in the independent evaluation of data mining algorithms and data management and emphasise in the unsupervised methods. It also allows arbitrary data types, file formats, or distance or similarity measures.

3. C++

The superfast C++ programming language is also very popular in the field of machine learning. This powerful language gets supported by most of the machine learning platforms. If you have some good working knowledge using C++ then it is a pretty good idea to learn machine learning using C++. C++ is much efficient compare to most of the programming languages. Many powerful libraries such as TensorFlow and Torch are implemented in C++ programming language so machine learning and C++ is truly a great combination. 
 

• TensoFlow: Google’s open-source TensorFlow is used to do numerical computations on any CPU or GPU using data flow graphs and make decisions with whatever information it gets.
• Torch: A open-source machine learning library which makes scientific and numerical operation easier by providing a large number of algorithms. it makes for easier and improved efficiency and speed.
• mlpack: A superfast, flexible machine learning library which provides fast and extensible implementations of cutting-edge machine learning algorithms using C++ classes which can be integrated into larger-scale machine learning solutions

4. R

R is a very popular programming language for statistical computing, analysis, and visualizations in machine learning. It is a perfect graphics-based language for exploring the statistical data via graph vastly used by data professionals at Facebook, Google etc. Though R is highly preferable in bioengineering and the biomedical statistic it is also popular on implementing machine learning like regression, classification, and decision tree formation. 
 

• xgboost: this is used for implementing the gradient boosting framework and is popular for it’s performance and speed. It supports various objective functions like regression, classification and ranking and is extensible so that you can define your own objectives easily.
• mlr: It is an extensible framework for classification,regression and clustering problems and has easy extension mechanism through s3 inheritance.
• PARTY: this package is used for recursive partitioning. This package is used to build decision trees based on Conditional Inference algorithm. This package is also extensively, which reduces the training time and bias.
• CARET: this package is developed to combine model training and prediction for several different algorithms for a given business problem and helps to choose the best machine learning algorithm.

5. Javascript

It is one of the most widely used, high-level and dynamically typed language which is flexible and multi-paradigm. Javascript is also so popular in ML that high profile projects like Google’s Tensorflow.js are based on JavaScript. If you are a master of Javascript then literally you can do everything from full-stack to machine learning and NLP. 

• Brain.js: It is a GPU accelerated, easy to integrate neural networks in JavaScript which is used with Node.js in the browser and provides multiple neural network implementations to train to do different things well. It is so simple to use that you do not need to know Neural Networks in details to work with this.
• Tensorflow.js: It is a popular library for machine learning in JavaScript. You can build and train models directly in JavaScript using flexible APIs and almost any problems in Machine Learning can be solved using Tensorflow.js. You can also retrain the existing ML models using your own data.
• machinelearn.js: It is the saviour of Javascript which is a replacement of python’s ScikitLearn library. It provides clustering, decomposition, feature extractions models and utilities for supervised and unsupervised learning.
• face-api.js: A ready-to-use APIs which includes implementations of well-known Face Detection and Recognition models which is pre-trained with a wide variety of datasets. It gives you the flexibility to directly plug into any Node.js and browser environments. Being lightweight this library can be used on both mobile and web browsers with no issues.

Among these programming languages, Python remains the most popular in the field of ML. Though languages like JavaScript are the rising star and overtime maybe it can reach the top. So it is a good recommendation to choose theses languages. 

System Design Dropbox….You might have used this file hosting service multiple times to upload and share the files or images but what if somebody asks you to design this gigantic system within just 45 minutes?

Yes, this is what you are expected to do in your system design round of interviews. We are not joking but you need to tell your approach about designing a system like dropbox (within 45 minutes or less) which has hundreds of software engineers working on it for a decade. System Design dropbox (or design google drive or any other file sharing and upload service) is a quite common question of system design round.

In this blog, we will discuss how to design a website like dropbox or google drive but before we go further we want you to read the article “How to crack system design round in interviews?“. It will give you an idea that what this round looks like, what you are expected to do in this round and what mistakes you should avoid in front of the interviewer.

Now let’s jump to the question straightforward “How would you design Dropbox?”

How Would You Design Dropbox?

Don’t jump into the technical details immediately when you are asked this question in your interviews. Do not run into the one direction, it will just create confusion between you and the interviewer. Most of the candidates make mistakes here and immediately they start listing out some bunch of tools, frameworks, or databases. Remember that your interviewer wants high-level ideas about how you will solve the problem. It doesn’t matter what tools you will use, but how you define the problem, how you design the solution, and how you analyze the issue step by step.
In this blog, instead of talking a lot about the web kind of services, we will assume there is a sync client installed in your computer or system and that client is always looking into particular sync folders in which it is always monitoring the changes to the files and uploads it. Also, we won’t be talking about how do we build the cloud storage. We will use some cloud storage services like Amazon S3 or any other storage services that keep the file in the cloud.

1. Discuss About The Core Features

Before you jump into the solution always clarify all the assumptions you’re making at the beginning of the interview. Ask questions to identify the scope of the system. This will clear the initial doubt and you will get to know what are the specific detail interviewer wants to consider in this service. So start with the core features of dropbox to discuss with the interviewers. If the interviewers want to add some more features (such as API integration) they will let you know.

• User should be able to upload/download, update and delete the files
• File versioning (History of updates)
• File and folder sync

2. Traffic

• 12+ million unique users
• 100 million request per day with lots of reads and write.

3. Discuss The Problem Statement

A lot of people assume designing a dropbox is that all they just need to do is to use some cloud services, upload the file, and download the file whenever they want but that’s not how it works. The core problem is “Where and how to save the files?“.

Suppose you want to share a file that can be of any size (small or big) and you upload it into the cloud. Everything is fine till here but later if you have to make an update in your file then it’s not a good idea to edit the file and upload the whole file again and again into the cloud. The reason is…

• More bandwidth and cloud space utilization: To provide a history of the files you need to keep the multiple versions of the files. This requires more bandwidth and more space in the cloud. Even for the small changes in your file, you will have to back up and transfer the whole file into the cloud again and again which is not a good idea.
• Latency or Concurrency Utilization: You can’t do time optimization as well. It will consume more time to upload a single file as a whole even if you make small changes in your file. It’s also not possible to make use of concurrency to upload/download the files using multi threads or multi processes.

Discuss The Solution (High-Level Solution)

We can break the files into multiple chunks to overcome the problem we discussed above. There is no need to upload/download the whole single file after making any changes in the file. You just need to save the chunk which is updated (this will take less memory and time). It will be easier to keep the different versions of the files into various chunks.

We have considered one file which is divided into various chunks. If there are multiple files then we need to know which chunks belong to which file. To keep this information we will create one more file named as a metadata file. This file contains the indexes of the chunks (chunk names and order information). You need to mention the hash of the chunks (or some reference) in this metadata file and you need to sync this file into the cloud. We can download the metadata file from the cloud whenever we want and we can recreate the file using various chunks.

Now let’s talk about the various components for the complete system design solution of dropbox service.

Let’s assume we have a client installed on our computer (an app installed on your computer) and this client has 4 basic components. These basic components are Watcher, Chunker, Indexer, and Internal DB. We have considered only one client but there can be multiple clients belongs to the same user with the same basic components.

• The client is responsible for uploading/downloading the files, identifying the file changes in the sync folder, and handling conflicts due to offline or concurrent updates.
• The client is actively monitoring the folders for all the updates or changes happening in the files.
• To handle file metadata updates (e.g. file name, size, modification date, etc.) this client interacts with the Messaging services and Synchronization Service.
• It also interacts with the remote cloud storage (Amazon S3 or any other cloud services) to store the actual files and to provide folder synchronization.

Discuss The Client Components

• Watcher is responsible for monitoring the sync folder for all the activities performed by the user such as create, update or delete files/folders. It gives notification to the indexer and chunker if any action is performed in the files or folders.
• Chunker break the files into multiple small pieces called chunks and upload it to the cloud storage with a unique id or hash of these chunks. To recreate the files these chunks can be joined together. For any changes in the files, the chunking algorithm detects the specific chunk which is modified and only saves that specific part/chunks to the cloud storage. It reduces the bandwidth usage, synchronization time and storage space in the cloud.
• Indexer is responsible for updating the internal database when it receives the notification from the watcher (for any action performed in folders/files). It receives the URL of the chunks from the chunker along with the hash and updates the file with modified chunks. Indexer communicates with the Synchronization Service using the Message Queuing Service, once the chunks are successfully submitted to the cloud Storage.
• Internal database store all the files and chunks information, their versions, and their location in the file system.

Discuss The Other Components

1. Metadata Database

The metadata database maintains the indexes of the various chunks. The information contains files/chunks names, their different versions along with the information of users and workspace. You can use RDBMS or NoSQL but make sure that you meet the data consistency property because multiple clients will be working on the same file. With RDBMS there is no problem with the consistency but with NoSQL, you will get eventual consistency. If you decide to use NoSQL then you need to do different configurations for different databases (For example, Cassandra replication factor gives the consistency level).

Relational databases are difficult to scale so if you’re using the MySQL database then you need to use a database sharding technique (or master-slave technique) to scale the application. In databases sharding, you need to add multiple MySQL databases but it will be difficult to manage these databases for any update or for any new information that will be added to the databases. To overcome this problem we need to build an edge wrapper around the sharded databases. This edge wrapper provides the ORM and the client can easily use this edge wrapper’s ORM to interact with the database (instead of interacting with the databases directly).

2. Message Queuing Service

The messaging service queue will be responsible for the asynchronous communication between the clients and the synchronization service.

Below are the main requirements of the Message Queuing Service.

• Ability to handle lots of reads and writes requests.
• Store lots of messages in a highly available and reliable queue.
• High performance and high scalability.
• Provides load balancing and elasticity for multiple instances of the Synchronization Service.

There will be two types of messaging queues in the service.

3. Synchronization Service

The client communicates with the synchronization services either to receive the latest update from the cloud storage or to send the latest request/updates to the Cloud Storage.

The synchronization service receives the request from the request queue of the messaging services and updates the metadata database with the latest changes. Also, the synchronization service broadcast the latest update to the other clients (if there are multiple clients) through the response queue so that the other client’s indexer can fetch back the chunks from the cloud storage and recreate the files with the latest update. It also updates the local database with the information stored in the Metadata Database. If a client is not connected with the internet or offline for some time, it polls the system for new updates as soon as it goes online.

4. Cloud Storage

You can use any cloud storage services like Amazon S3 to store the chunks of the files uploaded by the user. The client communicates with the cloud storage for any action performed in the files/folders using the API provided by the cloud provider.

A lot of candidates get afraid of this round more than the coding round because they don’t get the idea that what topics and tradeoffs they should cover within this limited timeframe. Firstly, remember that the system design round is extremely open-ended and there’s no such thing as a standard answer. Even for the same question(System Design Dropbox), you’ll have a different discussion with different interviewers.

Do you ever wonder about the sudden emergence and popularity of Blockchain? What is it? Well, Blockchain is literally a chain of blocks as the name suggests! It’s just that the “blocks” in this context are digital information that is connected using cryptography. Each of these blocks contains a cryptographic hash function linking to the previous block, a timestamp, and the digital information in the block. These blocks are structured in such a way that it is very difficult to modify the data and so they ensure transparency while simultaneously maintaining security.

Blockchain is actually synonymous with security as tampering with these blocks is next to impossible! And that makes this technology very popular in fields like banking, finance, etc. In fact, Blockchain was first made popular when it was used in the implementation of the BitCoin. After all, people want their money to be as secure as possible! And so currently, Blockchain developers are highly in demand. Learning the top programming languages for Blockchain Development will definitely give you an edge over other developers so that’s what this article is all about.

1. C++

C++ is popular all across the tech world and this is true even in Blockchain technology! C++ is so popular for blockchain because of its multiple capabilities such as move semantics, primitive control over memory, advanced multi-threading, and other object-oriented features like function overloading, runtime polymorphism, etc. These different OOPS features of C++ allow Blockchain developers to easily mold data and functions together in a single module, just like Blockchain molds the blocks with cryptographic chains. In fact, C++ is also so popular with Blockchain as Bitcoin, which is a cryptocurrency and the first-ever implementation of Blockchain was originally written in C++. 

2. Python

Python is fast becoming the most popular programming language in the world and if you are a new developer experience in Python, then it might be the best Blockchain language for you. A problem with Python is that it is an interpreted language and that creates some problems for complex cryptographic operations in Blockchain. However, Python is an object-oriented language which helps in managing many of its performance-related overheads. Another benefit of Python is that developers can prototype their ideas quickly with any long-winded coding required. Python also has huge opensource support which makes it ideal for Blockchain. There are many Python libraries, plugins, and other resources available online for almost every problem you can encounter in Blockchain development.

3. Java

Java provides stiff competition to C++ in popularity and usefulness. This is true in Blockchain technology as well! Java has an abundant Application Programming Interface (API) that includes many Java classes, packages, interfaces, etc. This is useful for constructing applications without necessarily knowing their inside implementations. Also, the one property of Java that is particularly useful in Blockchain is its portability. Java programs can be ported onto different platforms because of its WORA(“write once, run anywhere”) functionality. These programs are not dependent on system-specific architecture as they use the universal JVM(Java Virtual Machine) for execution. This portability along with the other popular features of Java makes it perfect for Blockchain.

4. Solidity

Solidity is one of the fastest-growing blockchain programming languages that was created for writing smart contracts that run on the Ethereum Virtual Machine (EVM). It was developed by Ethereum which is a blockchain-based distributed computing platform and operating system. Since Solidity is created keeping Blockchain in mind, it is suited to solving many of the problems faced by Blockchain developers. Solidity is developed similar to the ECMAScript syntax but it has features like variadic return types, static typing, etc. So it is a great language to learn if you want to focus specifically on Blockchain development in depth.

5. Vyper

Vyper is a new Blockchain programming language that is derived from Python 3. So the Vyper syntax is also valid Python 3 syntax, even though Vyper does not have all of Python’s features. Vyper is created as an alternative to Solidity. It is usually used for the Ethereum Virtual Machine (EVM), just like Solidity is. However, Vyper has different control structures than Solidity and it also handles security issues differently. Vyper has also don away with much of the OOPS functionalities in Solidity along with other features like infinite loops, modifiers, recursive calling, etc. This helps in avoiding the security issues that arise because of these features. So if you want a Blockchain development language for writing smart contracts, check out Vyper!

6. Golang

Go is a great programming language for building fast and efficient Blockchain systems. It is the best language for creating hyper ledger fabric, which is a foundation for developing applications for Blockchain. Since Go is statically-typed and a compiled programming language, it is perfect for Blockchain coding. It also has other features that enhance performance such as generics, classes and inheritance, constructors, annotations,  exceptions, etc. Go is also an uncomplicated language that can be learned easily. This is obvious by the fact that there are around 800,000+ developers on the Go language network.

7. C#

C# is syntactically similar to Java and C++ so it is ideal as a Blockchain programming language. While C# was initially created only as a Microsoft language, it is now quite popular and considered one of the best programming languages for blockchain. Open-source developers can easily create a highly portable code using C# that will run across all devices and multiple operating systems such as Windows,  Linux, Mac, Android, etc. Also, since C# is an OOPs programming language, Blockchain developers can obtain maximum performance when developing their next blockchain. Projects written in C# include Stratis, a Blockchain-as-a-Service provider that allows businesses to easily create applications on Blockchain platforms.

8. JavaScript

JavaScript is the most popular web language and thanks to NodeJS, a JavaScript runtime environment, JavaScript is quite popular with Blockchain developers as well. They can build highly-capable and creative Blockchain applications with JavaScript because it is already installed on most systems. This is a big advantage JavaScript has against other programming languages since every web system uses JavaScript in some capacity. So developers do not need to worry about integration while using JavaScript and they can just focus on the application logic for the Blockchain. An example of this is the Lisk Sidechain Development Kit (SDK) that allows developers to build, publish, and distribute their Blockchain applications which are written in JavaScript. 

9. Simplicity

Simplicity is a high-level Blockchain development language that was created for smart contracts. In fact, it is one of the best programming languages to write smart contracts, both for professional programmers and open source developers. Simplicity is also focused on reducing the complex and low-level understanding of the Bitcoin Script. Since it hides the low-level logical components from Bitcoin developers, Simplicity increases the work capacity of developers which helps to create a much faster development period. Simplicity is also compatible with the Elements platform, which is an open-source, Blockchain platform with sidechain capabilities. So Blockchain developers building sidechains on Elements can also use the many functions and features of simplicity.

10. Rholang

Rholang is a great programming language for the development of smart contracts. This language has a functional approach rather than an object-oriented approach which is quite helpful in solving many blockchain problems. that is one of the reasons for its popularity. Rholang applications evaluate the whole program as a series of functions and solves them sequentially. This is markedly different from languages like C or Python that use variables for storing data and change the value of the variables with time. Therefore, Rholang has a functional programming paradigm rather than an object-oriented one with it being the most popular Blockchain development language in this category.

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Are you working as a junior developer and want to make a jump in your career? … Have you spent a few years in the industry as a developer and have the desire to become a senior developer? 

If you’re one of the coders, developers, or programmer who is looking for the best resources and guidelines to excel in his/her field then this article is for you. 

Everyone wants to level up their skill set to become a better developer at their job. As a developer, we all want appreciation for our work and we all want to be respected by other co-workers. We all want to accomplish more and more and we all want to see ourselves one step ahead than others. Well, in the world of programming it’s not easy to keep learning and growing continuously when every day new technologies are coming out and there is so much information to learn. It can be overwhelming or it can be difficult and confusing as well. 

Every year so many developers and students are coming out from different colleges and there is so much competition involved in the jobs among all of them. Now the question is…what is the smartest and efficient way to learn and acquire the right skill set to become a senior developer? what exactly makes someone a senior developer? what characteristics do they possess that make them set apart from everyone else? Before we go dig into this topic we need clearly understand What Defines a Senior Developer? If you think that a senior developer can code 10X times faster or a senior developer can code in 10-12 different languages than you’re wrong…let’s clear out this myth first and understand what is a senior developer.

What Defines a Senior Developer?

A senior developer is not someone who can code in 10 different languages. A senior developer is someone who observes the problem and sees it from different angles. They are the ones in industries who bring an incremental benefit to the table. A senior developer understands the business values and cares about the product. They set a long term vision and work towards it consistently. They believe in creating and delivering a product that provides maximum value for the client’s investment. They are someone who makes people around him or her better. 

You might be one of them who can code in multiple programming languages and you may know all the cool technologies and programming techniques but if you are unable to focus on delivering the actual value to the client than you aren’t a senior developer. A senior developer is not just a job title, you should have the ability to deliver real benefit to the stakeholders. You need to build a product thinking about it from a future perspective and you need to provide maximum benefit to your customer. So the most important factor that will decide a real job title of the ‘senior developer’ is…What value do you bring to your company/business/client? 

How to Become a Senior Developer?

Finally, your curiosity is going to end and we will discuss some characteristics of the senior developers in detail here. In every industry, people hold different years of experience in the same field. You will always find someone with more experience than you and someone with less experience as well, but here we will discuss the set of characteristics that make someone smarter than other developers and deserve the real title of ‘senior developer’. In the field of technology, it’s not enough to have just one skill set. To level up your career you should have a different skill set and here we will highlight that skill set in detail. You need to focus and work actively on this skill set to become an excellent senior developer. 

1. Technical Skills

If we are talking about programming, development, or coding than the first skill which comes to everyone’s mind is the technical skill. You do indeed need this skill but here we are not going to talk about being excelled in multiple languages or technologies. A senior developer spends time understanding why a specific technology is being used in a specific product? Why should I choose a specific technology or specific language to build a specific product? Why a certain problem exist? Why does this framework exist? What problem a library or a specific database can solve? 

A senior developer is good at picking up the right tools and technology that works for a specific product. A project can give maximum benefit to its client if these tools and technologies are chosen carefully. So a senior developer carefully pays attention to the pros and cons of these technologies before picking them up for any project. They should have a good sense of all of the tools and ideas that can benefit the development lifecycle. They also think about continuous improvement in the delivery process to provide a better product. 

They understand the complete architecture of the product and how things are connected. They also think about the different problems a product may face if it grows or scales in the future. Technologies and frameworks get change every time but a senior developer should know the principle of computer science fundamentals such as Data Structures, Algorithms some other higher-level computer science topics. Understanding these higher-level topics helps in solving most of the software problems throughout different languages and time. 

2. Team Skills

Somewhere this skill comes under behavioral skillset. A good team player provides the most value to a company. How can you make your co-workers around you better? the answer to this question defines how good you are as a team member and as a senior developer. How do you treat other team members? How do you work with coworkers? How you are trying to collaborate with them? Are you brash and opinionated with PR (pull request) reviews, and contribute to a toxic culture? Are you an encouraging and cooperative team member? 

Senior developers offer help to other team members, and if they don’t know something they also try to learn it and ask questions to other team members as well. They don’t show their large egos and they are always open to receive feedback from others. They do not write complicated code just to show off their skills. They write code simple, clean, and readable that can be understandable by other team members. In short, for any project, if you are willing to get along with your teammates and make others work well together, you’re already miles ahead of most people. 

3. Communication and Client/User Skills

Are you able to communicate properly with your clients and understand what their needs are?? Do you understand what problems your clients are facing and how to offer the best solution to the clients for those problems? Talking to the client is one of the difficult tasks. You need to be a great listener and you need to understand what problems asking some relevant questions. A senior developer interacts with the clients, understand the needs and problems, discuss the budget, and then offer the best solution within the abilities of the organization. You need to form a good relationship with them and you need to be a transparent communicator. Share your opinions (but do not push your opinion on clients), give them the right level of detail, and help them to make some smart, informed decisions. You may also have to explain complex programming topics to the non-technical person. Watch this video and observe how to explain the complex topics clear to the audience. 

4. Curiosity For Learning

Seniors developers are usually amazing self-learners and they are always passionate about technologies or development. They believe in learning something new every day and they are curious about everything in the programming world. They love to explore new topics and they love to speak to the other developers. They read blogs, they ask questions and they have a growth mindset. Continuous learning and curiosity set them apart from other developers. If a senior developer doesn’t know the answer for something he/she will try to find the solution from different resources no matter what. They will try to talk to the right people and they know how to grow every day with continuous learning. 

They know that in programming learning everything is impossible but that doesn’t mean they just focus on one skillset. They focus on things that matter most and they spend time which they love to enjoy. They don’t give biased opinions towards any technology, language, framework, or library. They know that everything has some pros and cons, so instead of hating any framework, library, or language, and giving advice to others for not using it, they simply share the opinion where the specific technology is good to use and where it is not. They try to learn the concept before they decide they hate something. 

5. Community Skills

Senior developers love to share the information with the industry and love to join the developer’s community. Whether it’s a meetup or some tech talks, they love to attend these things and they love to interact with other people there. Instead of just being in a closed-off box and taking care of the responsibility given in the office environment they chose to go outside and interact with other communities. This helps them to get more knowledge from other industries and what’s new happening in the technical world. Their boundaries are not just limited to the problems they are working in the industry. They also love to join online communities and solve the problems of other developers sitting across the world. They love to share the information and solution for any problem by using various resources such as blogs and articles. They discuss the problems and the solution with other developers. They always try to find the best possible solution using various online resources.  

This is a Java Program to Display a Clock Using Applet

Problem Description

We have to write a program in Java such that it creates an analog clock which displays the current system time.

Expected Input and Output

For displaying a clock, we can have the following set of input and output.

To View the Clock :

When the program is executed,
it is expected that the applet consists of a clock,
and the clock displays the current system time.

Problem Solution

1. Create a thread and delay each execution by 1 seconds.
2. Get the hour, minute and second parameters from the system time.
3. Create the clock and label the hours on it.
4. Draw the hours hand, minutes hand and the seconds hand based on the current system time.

Program/Source Code

Here is source code of the Java program to display a clock. The program is successfully compiled and tested using javac compiler on Fedora 30. The program output is also shown below.

To compile and run the program use the following commands :

>>>javac Clock.java
>>>appletviewer Clock.java

Program Explanation

1. Use Thread.sleep(int) to delay the execution by entered time in milliseconds.
2. Create a circle for the clock and label the hours on it.
3. Each hour on the clock is equivalent to 30 degrees. The angle of hours hand from the y=0 line, is ((30*hour)-90) degrees.
4. Each minute on the clock is equivalent to 6 degrees. The angle of minutes hand from the y=0 line, is ((6*minute)-90) degrees.
5. Each second on the clock is equivalent to 6 degrees. The angle of seconds hand from the y=0 line, is ((6*second)-90) degrees.
6. To get the position of the hands of clock, it is required to convert the angles to radians. To do this, use Math.toRadians function.
7. The x co-ordinate of any point on a circle with center (a,b) and radius ‘r’ measuring an angle θ from the center is given as x = a + r * cosθ .
8. The y co-ordinate of any point on a circle with center (a,b) and radius ‘r’ measuring an angle θ from the center is given as y = v + r * sinθ .

Runtime Test Cases

Here’s the run time test cases for creating a clock for different input cases.

Test case 1 – To View the Clock. (When time is 18:10:06)

Test case 2 – To View the Clock. (When time is 18:12:23)

Test case 3 – To View the Clock. (When time is 18:14:35)

Sanfoundry Global Education & Learning Series – Java Programs.