Learning java android development

Where To Learn Java For Android App Development

Play Store, the official Android app store, hosts about 3 million Android apps for now. More than 80% of smartphones in the world run on Android. These are huge numbers with a clear message hidden within — Android app development would fast-forward your career to new heights.

Besides fetching you highly paid jobs, being an Android app developer lets you unleash your creativity and solve practical problems faced by Android users across the world.

Learning Java is pivotal to Android app development. I have been a Java programmer for years and in this article, I am sharing a plan to help you learn it in a systematic yet fun way.

Topics to Learn for Android App Development

Being a successful Android developer needs familiarization with different knowledge areas. Your app idea would be best executed when you learn all of them steadily by taking one step at a time to avoid being overwhelmed. I recommend the following road map, followed by plenty of practice to utilize your time effectively.

Core Java

These are the basics that you must learn before you get to Android app development. Focus on learning object-oriented programming so that you are able to divide your program into modules and write reusable code.

Java is a universal choice for programmers looking for a robust, easy-to-use coding language with cross-platform capabilities.

You can break it down into six different parts and focus on learning one at a time:

Testing Libraries

Libraries are great time-savers. They allow you to call upon a pre-written set of instructions and implement commonly used functionalities without having to code it from scratch.

Testing Libraries such as JUnit and PowerMock Mockito save you writing long fragments of code to unit test your program. These are particularly recommended for Test-Driven Development (TDD) where the creation of tests ahead of actually writing the code of your application drives the pace of development. You would be using Java testing libraries throughout your career and I urge you to get accustomed to these early.

Android SDK (Software Development Kit)

It is an Android developer’s toolbox. It is the only constant in your Android app development journey, as you would likely be using many programming languages and IDEs in your career.

Once you write your Java code for developing an Android app, you need a way to execute it on Android devices and utilize the full potential of the Android Operating System. This is where the SDK comes in — it is the complete package containing documentation, libraries, code samples, and processes that you can integrate into your application.

The SDK also has emulators for Android, that you can invoke to see how your code would perform on an actual Android device.

You will need to master working with databases even for writing entry-level Java programs for Android. Applications need to store data in tables and retrieve it as and when required, subject to required conditions. Structured Query Language (SQL) is the last piece in your Java app development puzzle. There are many variants of SQL, but SQLite is the one that is used on Android devices. Pay special attention to it, as it would complete a solid foundation on which you can build your Java programming career.

Training and Practice

Now it is time for you to apply all your learnings to practice and build confidence. It is OK if you do not feel confident enough to start writing codes — practicing is the only way to build your programming skills and test them out. Pick up small tasks and write programs to solve them. Do not let mistakes set you back, as even the most experienced programmers make it. Learn from your mistakes, set them right, and move on to more difficult problems.

Later in the article, I’ve included some online resources you could refer to for learning and practice.

Getting Started with Building Android Applications

As I mentioned earlier, an Android developer requires a set of tools to develop, deploy, test, simulate, and improve his application. I recommend the following, especially if you are a beginner without prior programming experience:

Step 1: Download Android Studio

You need a development environment to build applications. Android Studio is an official IDE, as it’s recommended by Google. It offers an entire set of tools that a developer would need, i.e. APK Analyzer, Visual Layout Editor, Fast Emulator, Intelligent Code Editor, Real-time profiler, and much more. Download it and you have your Android development toolbox ready.

Step 2: Configure Android Studio

Android Studio has an easy-to-follow installation wizard. Just follow the installation instructions and you will be done in no time. I recommend sticking to the default settings to start with — customizations can come later.

Keep in mind that having Java Development Kit is a prerequisite for Android Studio. Download JDK and follow simple installation instructions if you do not have it on your system already. I would recommend OpenJDK, particularly if you are a beginner.

Step 3: Launch New Android Project

All the magic happens inside an Android Studio project. A project contains all the components you need to get your Android app idea off the ground, up and running. Your workspace, source code, assets, test code, and other related configurations — everything is placed inside a project.

Once you complete your development process, all project contents are packaged into an APK (Android Application Package). Make sure you choose your project name wisely, as your package name (that would eventually go into Google’s Play Store) takes the format:

Step 4: Creating Your Android App

By now, you have done all the groundwork — you have acquired the skills and tools required for making your first Android app using Java. It is time to let your creativity take center stage. Android Studio workspace will show your directory structure, an Android phone with the words “Hello World” on its virtual screen. Let your programming skills bring your app idea alive!

Top Java Resources for Android Development

Now that you know what you need to learn, it is time to choose where to learn it from.

CodeGym

CodeGym offers a practice-oriented Java course to make learning enjoyable and effective. The website is founded on the belief that everyone can be a programmer if guided correctly.. 80% of its Java course consists of hands-on exercises so what you learn in theory is promptly put to test. There are over 1200 tasks organized in order of increasing difficulty so that you keep learning and monitor your progress through a virtual mentor.

Javarevisited

Javarevisited is an encyclopedia in itself on Java programming. It has tutorials, articles, practice problems, and tasks to give you everything you need to explore Java’s vast universe.

Other than systematically covering the nuances of Java, the site discusses innovative ideas that would be helpful to you throughout your career as an Android developer. It also points you to other useful online resources so that you keep learning.

Codecademy

Codecademy is a well-known educational website for learners looking for programming courses, tutorials, certifications, and much more. There are over 50 lectures and quizzes in Java and other programming languages to learn and test your knowledge. You can even get your code reviewed by one of the community experts.

The website lets you create your own learning schedule and test your understanding by solving problems so you are never out of practice.

Codewars

It offers a different dimension to your experience of learning Java programming. It is not a conventional tutoring website. Rather, it is for the time when you want to break away from the monotonous tutorials and want to challenge yourself. Codewars has a repository of assignments in Java (and many other programming languages) that keep you glued. You can interact with a community of experienced developers who would analyze your codes in detail and provide thorough feedback so that you learn faster.

GeeksforGeeks

If you are not much of a theory person and grasp concepts better when they are exemplified, this is the portal tailor-made for you. GeeksforGeeks is a free resource that covers all aspects of computer science. It hosts an elaborate collection of Java resources and thoroughly covers the overview of libraries, collections, lists, queues, OOP, maps, etc.

Java Fundamentals by Pluralsight

Many learners I come across focus too much on syntax and libraries. They try to memorize these instead of focusing on the principles Java is built upon. Pluralsight introduces you to design patterns that help you code while keeping an eye on the big picture.

Take this course once you have completed core Java concepts and are ready to start coding. You would learn smart ways to write programs and organize your object according to their usage.

Online Communities I Recommended for Java Learners

Programming is as much an art as it is science. You are bound to hit roadblocks — do not feel bad about seeking help whenever you need it. Java has a very helpful and active community spread across the world where experienced programmers would provide you critical feedback and solutions.

Here are some of the online forums I strongly recommend:

Conclusion

Now you have an organized roadmap to pursuing your goal of learning Java and developing Android apps. Get started today and get your hands dirty with codes as soon as you can — that is the best way to make progress. Do not feel shy about making mistakes or seeking help, as an expert programmer of today was once a beginner who refused to give up.

Javarevisited

Medium’s largest Java publication, followed by 13500+ programmers. Follow to join our community.

Источник

Learn Java For Android App Development – A Complete Guide

Java is one of the powerful general-purpose programming languages, created in 1995 by Sun Microsystems (now owned by Oracle). Java is Object-Oriented. However, it is not considered as pure object-oriented as it provides support for primitive data types (like int, char, etc). Java syntax is similar to C/C++. But Java does not provide low-level programming functionalities like pointers. Also, Java code is always written in the form of classes and objects. Android heavily relies on the Java programming language all the SDKs required to build for android applications use the standard libraries of Java. If one is coming from a traditional programming background like C, C++, Java is easy to learn. So in this discussion, there is a complete guide to learn Java specifically considering Android App Development.

So in this article, we have covered the following things:

1. Basics of Java
2. Decision Making Statements in Java
3. Type Conversion in Java
4. Comments in Java
5. Operators in Java
6. Strings in Java
7. Object-Oriented Programming Concepts in Java
8. Exception Handling in Java
9. Interfaces and Abstract Classes
10. Essential collections in Java required for Android Development
11. Miscellaneous
12. Complete Java Tutorial

Step-by-Step Guide to Learn Java for Android App Development

Basics of Java

Decision Making Statements in Java

• Decision Making in Java (if, if-else, switch, break, continue, jump) – A programming language uses control statements to control the flow of execution of a program based on certain conditions.
• Switch Statement in Java – The switch statement is a multi-way branch statement. It provides an easy way to dispatch execution to different parts of code based on the value of the expression.
• Loops in Java – Looping in programming languages is a feature that facilitates the execution of a set of instructions/functions repeatedly while some conditions are evaluated to be true.
• For-each loop in Java – For-each is another array traversing technique like for loop, while loop, do-while loop is introduced in Java5.

Type Conversion in Java

• Type conversion in Java with Examples – If the data types are compatible, then Java will perform the conversion automatically known as Automatic Type Conversion, and if not, then they need to be cast or converted explicitly.

Comments in Java

• Comments in Java – Comments take part in making the program become more human-readable by placing the details of code involved and proper use of comments makes maintenance easier and finding bugs easier.

Operators in Java

• Operators in Java – Java provides many types of operators which can be used according to the need. They are classified based on the functionality they provide.

Strings in Java

• String class in Java | Set 1 – String is a sequence of characters. In Java, objects of strings are immutable, which means constant and cannot be changed once created.
• StringBuffer class in Java – StringBuffer is a peer class of String that provides much of the functionality of strings.
• StringBuilder Class in Java with Examples – The StringBuilder in Java represents a mutable sequence of characters.

Object-Oriented Programming Concepts in Java

• Classes and Objects in Java – The basic OOPs components Class and Object in the java programming language.
• Different ways to create objects in Java – Get to know the various ways of creating objects in Java.
• Inheritance in Java – It is the mechanism in Java by which one class is allowed to inherit the features(fields and methods) of another class.
• Encapsulation in Java – Encapsulation is defined as the wrapping up of data under a single unit.
• Abstraction in Java – Data Abstraction is a property by virtue of which only the essential details are displayed to the user.
• Access Modifiers in Java – As the name suggests, access modifiers in Java help to restrict the scope of a class, constructor, variable, method, or data member.
• ‘this’ reference in Java – ‘this’ is a reference variable that refers to the current object.
• Overloading in Java – Overloading allows different methods to have the same name, but different signatures of methods.
• Overriding in Java – Overriding is a feature that allows a subclass or child class to provide a specific implementation of a method that is already provided by one of its super-classes or parent classes.
• Object class in Java – Object class is present in the java.lang package. Every class in Java is directly or indirectly derived from the Object class.
• Static class in Java – Some classes can be made static in Java. Java supports Static Instance Variables, Static Methods, Static Block, and Static Classes.

Exception Handling in Java

• Exceptions in Java – An exception is an unwanted or unexpected event that occurs during the execution of a program i.e at run time.
• Types of Exception in Java with Examples – Java also allows users to define their own exceptions.

Interfaces and Abstract Classes

• Interfaces in Java – Like a class, an interface can have methods and variables, but the methods declared in an interface are by default abstract.
• Access specifier of methods in interfaces – All methods in an interface are public, even if we do not specify public with method names. Also, data fields are public static final even if we do not mention them in field names.
• Access specifiers for classes or interfaces in Java – Methods and data members of a class/interface can have one of the following four access specifiers.
• Abstract Classes in Java – Java, a separate keyword abstract is used to make a class abstract.
• Difference between Abstract Class and Interface in Java – Get to know the differences between the interfaces and abstract classes.
• Anonymous Inner Class in Java – It is an inner class without a name and for which only a single object is created.

Essential collections in Java required for Android Development

• ArrayList in Java – ArrayList is a part of the collection framework and is present in the java.util package. It provides us with dynamic arrays in Java.
• HashMap in Java with Examples – It stores the data in (Key, Value) pairs, and you can access it via an index of another type.

Miscellaneous

• Java Naming Conventions – Naming conventions must be followed while developing software in Java for good maintenance and readability of code.
• Generics in Java – Generics mean parameterized types. The idea is to allow types ( Ingers, strings, … etc, and user-defined types) to be a parameter for methods, classes, and interfaces.
• Annotations in Java – Annotations are used to provide supplemental information about a program.
• Lambda Expressions in Java 8 – Lambda expressions basically express instances of functional interfaces (An interface with a single abstract method is called a functional interface.

For a complete Java Tutorial, you may refer to this article: Java Programming Language

Источник