Fundamentals of java programming. Java programming for beginners

Most recently, we held a webinar and, as owners of online Java courses, we were asked to tell you how you can learn Java on your own. We decided to write some proven ways to learn Java or how to learn programming from scratch in general.

So, you have firmly decided to become a Java programmer. And immediately you have a lot of questions: “Where to start learning Java? How to choose the right training program? How to learn Java and gain work experience?”.

Today there are many ways to learn something, and programming is no exception. In addition to the classic methods - self-study and offline programming courses - there are now many online Java courses, trainings, both paid and free.

We have highlighted the most popular ways to learn programming on your own.

So, several ways to learn Java:

1. Self-study.

advantageThis way of learning is that you yourself can plan absolutely all aspects of your training - what, where, how and when to teach you.

disadvantagethe same is that not everyone has the willpower to master a huge amount of material on their own, read a bunch of books, get enough practical experience and not give up everything at the beginning of the journey. In addition, everyone will have doubts: “Am I on the right path, am I doing everything right?”.

2. Free online course.

advantage this method training is, of course, the cost - it simply does not exist, all materials are free and this is a huge plus.

FlawIt also lies in the fact that, as practice shows, not everyone has the motivation to complete an online course in Java or any other language, and many quit, in fact, without even starting to study.

3. Offline training.

advantagesuch a study of Java programming will be that you can communicate with the teacher live, in addition, there will already be a small community of your colleagues with whom you can discuss the questions that have arisen and their solutions.

Flaw- this is that, as a rule, such courses are not taken at the most convenient time for mastering the material - in the evenings, and the time spent on the road back and forth can be very significant. In addition, the cost of the course includes the cost of renting the premises, equipment and materials for conducting classes.

4. Personal coaching/mentoring.

Advantagethis way to learn Java or another programming language is that you can find yourself an experienced mentor-mentor who will work with you personally, prepare individual tasks especially for you, do a code review of your code and point out your mistakes and gaps in knowledge.

the only disadvantageIt will be that the time of an experienced mentor is worth a lot, and finding a person who agrees to give you so much attention is not always easy.

5. And finally, training in the company.

There is an option to apply for any training courses in an IT company, where, most likely, you will work on a project that is quite close to real conditions, plus there is a high probability that after successfully completing the course, you will get a job in this company. However, the competition for such trainings is often very high and you need to already have confident knowledge in order to be accepted.

In any case, you can learn Java or learn programming from scratch, just find the way that suits you.

Good luck in all your endeavors! If you know some other methods and have seen in your practice that they work, write to us. We are always ready to communicate with people who are open to dialogue.

Do you want to learn how to program? Reasonable thought: such a skill, most likely, will not be superfluous. True, for this you will have to work a little. The cycle of classes brought to your attention, which will allow in the foreseeable future not only to get an idea of ​​​​what programming is, but also to learn how to create programs of non-trivial purpose and size.

There are several ways to learn programming.

The first and, perhaps, the most common - according to books. All that is needed is to find a suitable book and read it sequentially, page by page, and complete all the suggested exercises (if any). If the book is worthwhile (preferably from the authors of the technology or programming language), then this method, sooner or later, gives excellent results: you will know and understand most of the required material. But this method is long and of little use to those who are just starting to program and whose experience is limited to the most primitive information that he or she received at school or at work. You need to have a fair amount of patience, perseverance (often even stubbornness) in order to “break through” a lot of new concepts, concepts and unusual terminology. Still, books are good for those who have at least an initial knowledge of the subject and do not stop at every line just to simply understand what is at stake.

In addition, without experience, you are unlikely to choose exactly the book that will provide the necessary knowledge. The book market is littered with waste paper of high printing quality. But the value of most of these manuals, textbooks and books is more than doubtful. Sometimes a small and nondescript book at a ridiculous price turns out to be immeasurably more useful than a deluxe edition with excellent graphics on coated paper (and the price is ten to fifteen times more).

The second way is courses with an experienced teacher. The ideal option is when you and the teacher work as a couple: the teacher explains and shows, you try to repeat and develop. You can stop at any time and clarify what you do not understand. The teacher himself can adjust the pace of learning in accordance with your successes or failures. It is somewhat worse when there is only one teacher and several students. Usually this method also gives excellent results, provided that the group is not very large (say, 3, maximum 5 people) and the level of preparation of all students is approximately the same. If there is an opportunity and finances allow you to pay for such courses, it is better to use them.

Unfortunately, this method is not available to residents of small settlements where there are no training centers, as well as to those whose income level is not high enough to afford such a “luxury”. Of course, it happens that the employer at his own expense sends his employees to training courses, but then whoever is lucky.

The third way (and right off the bat, the best of all) is to work alongside an experienced mentor. Books are books, courses are courses, and a personal example, especially in real (“combat”) conditions, is just a godsend. Sometimes it is enough just to sit and observe, asking questions if necessary. If the mentor is a sane person (and real professionals, as a rule, are sane and friendly people), then in a few weeks you will get something that will allow you to start working on tasks of medium complexity and not constantly turn to reference books in search of elementary things. For such a period, of course, you will not become a professional, but you will not be a complete beginner either. Of course, in the process of learning, you need to remember the sense of proportion and not “get” a busy specialist with very elementary questions: first you need to look for the answer yourself. So you will get the necessary knowledge and skills almost free of charge and in a very short time.

But what if this method is not feasible, but you want to learn? Should I take the risk and turn to books? Still, the situation is not hopeless. We decided to prepare a small training course for beginners. This course contains only the essentials, but gives you enough understanding of the subject and skills that will allow you to continue on your own. Of course the absence feedback there will be a certain obstacle between us and you, but we hope that with some effort you will be able to learn something. In any case, we expect that after studying this course completely, you will be able to move on yourself. Of course, we do not promise you an easy life, but we will try to help. Before proceeding to the actual course itself, read and consider a few recommendations:

• Information Technology You can, of course, study without a computer, but you must admit that it is still more comfortable and practical with a computer; so a computer is needed. Any model not "older" than 5 years will do. There are no special requirements for the filling and hardware configuration, but remember the simple rules - the more RAM, the better, the better the monitor, the more convenient. In a word, do not save on trifles, but do not squander money in vain. A typical laptop costing around $500 or more is just right.
• The computer must have any modern operating system(which one is absolutely not important): Windows, Linux, MacOS, FreeBSD, etc. Since the vast majority of users have an operating system of the Windows family (of one version or another) from Microsoft on their computer, in the future we will focus primarily on it. You must be able to work on a computer (use the keyboard, mouse, USB devices, printer, connect to the Internet, etc.). Skills in working with text editors or spreadsheets. In general, remember that the main tool of a programmer (after the head, of course) is the keyboard, so if you have difficulty finding the spacebar on the keyboard, then you will have big problems. Only practice can help here.
• regarding the required for this course software, we will talk about it next time. We only note that to obtain it, you need access to the Internet. If you are reading these lines, then you already have such a way out.
• The course is designed for regular work. Resist the temptation to skip over what seems elementary to you and jump to next topic: this is fraught with unpleasant consequences, tk. you may miss a subtle point or an important detail.
• information technologies are oversaturated with specific terminology, mainly of English origin; almost all valuable documentation is written in English language. So it is useful to arm yourself with at least some kind of dictionary (any electronic dictionary will do, and not even the most powerful one) - gradually you will get used to and learn most of the necessary phrases and terms.
• The duration of each lesson is from 15 to 40 minutes. Each lesson should be studied completely: from cover to cover. We tried to make the course as clear as possible, but without water and long arguments. Examples program code must be typed and checked on your computer (this is not always feasible if the subject is large and the discussion stretches over several sessions, but sooner or later you should - even must - get the result that it should be).
• if you are tired, rest for a day or two. No disaster will happen. But not more. Do not try to catch up in a day for what you had to study for two months - you will get tired, confused and, in the end, disappointed in yourself or in what you were doing. If there is a break, then catch up slowly. The main thing is not to remember, but to understand. What is understood is remembered by itself. So no cramming.
• Get a notepad or notebook and mark in it what seems important to you. No need to take notes - write down only what you - just you - seemed interesting, stupid, funny. It can be a phrase, a piece of code, a quote, a cartoon, anything. Review older entries periodically; this will help you remember what you have learned.

Our approach is closest to the third way of learning - i.e. learning with a mentor. Our principle is simple: show and explain key details. We will not discuss simple and obvious things for a long, boring and tedious (if necessary, you will find enough information about them in books, documentation, and specialized forums). We will gradually develop a small application that will show you the work of a professional programmer. But "small" does not mean "simple" - not at all! To get the result you have to work hard. But do not be afraid - the result is worth it. The main thing is to want and follow the goal, overcoming hills and pits along the way.

Now let's take a break. Prepare the computer for the next lesson - make sure that there is at least 1 GB of free disk space on the hard drive; if the RAM is less than 1 GB, then find out if it can be increased and be sure to increase it (with RAM you should not save at all: if the computer allows you to install 4 GB, then install that much; believe me, it pays off with the comfort of work and saving time): we have a little boring, but necessary work to install multiple programs. So see you!

Barry Bird "Java for Dummies" Williams, 2013, 5th edition, 363 pages (8.23 mb. djvu)

About Java.

For dummies, it's like saying programming. It sounds trite, but Java is by far the most popular programming language. More programming is done on it than in C++ and C# combined. Start learning Java if you want to learn programming and you can't go wrong. The code written in this programming language is cross-platform. It will run on any device and under any operating system where the Java Virtual Machine (JRE) is installed - "Write once, work everywhere." The book "Java for Dummies" is designed specifically for them.

About the book.

If you have never studied programming and don't know about OOP, don't be discouraged, Barry Bird is good at explaining things. At least the basic concepts of object-oriented programming and basic knowledge of the Java language are guaranteed to you. Provided that you carefully study the material of the book and complete tasks in the form of code examples. In the guide, the author will talk about the history of the emergence of the Java language, its main concepts, advantages and disadvantages, existing versions and their differences, the tools necessary for coding and execution. ready programs(JDK, JRE, Eclipse).

Learn the basics: the grammar (syntax) of the language, the concept of API classes (standard libraries), write your first program. For the initial stage learning Java this book is sufficient. If you had the courage to finish reading it and complete at least part of the tasks, then you can start studying more voluminous and. The path to perfection has a beginning, but no end.

book title
About the author 13
Introduction 15
How to work with this book 15
Conventions Used in Book 15
What you can not read 16
A few guesses 17
Book 18 structure
Part I Java Basics 18
Part II. Creating a program in Java 18
Part III. Object Oriented Programming 18
Part IV. Advanced Programming Techniques 19
Part V. Gorgeous Tens 19
Part VI. Apps 19
Pictograms used in book 19
What's next 20
Looking forward to your feedback! twenty

Part I Java Basics 21

Chapter 1. Introduction to Java 23
What can be done with Java 24
Why write programs 25
A bit of history 25
Object Oriented Programming 28
Object Oriented Languages ​​28
Objects and classes 30
Benefits of an Object-Oriented Approach 31
Visual representation of classes and objects 32
What's next 33

Chapter 2 Software development 35
Quick start 35
What should be installed on the computer 37
What is a compiler 38
What is the Java 40 Virtual Machine
Development process 45
Integrated Development Environment 46

Chapter 3 Core Java Components 49
Let's talk on Java language 49
Grammar and Common Names 50
Words in Java 51 program
Your first Java 53 program
How Your First Program Works 54
Classes 54
Methods 55
Main method of program 57
How to tell the computer to do what you want 58
Curly brackets 60
Do not say “No comment…” 62
Adding comments to code 63
Don't be too hard on old Barry 66
Using Comments to Experiment with Code 66

Part II. Creating a Java program 69

Chapter 4 Variables and values 71
Changeable variable 71
Assignment operator 74
Types of values ​​and variables 75
Text Display 77
Numbers without decimal point 78
Initialization at declaration 79
Java 80 Primitive Types
Type char 81
type boolean 82
Reference types 83
Import declaration 86
Creating New Values ​​with Operators 87
Can be initialized once, but assigned many times 89
Increment and decrement operators 89
Assignment operators 93

Chapter 5 Control Instructions 95
Making a Decision with an if Statement 95
Guess the number 96
Entering text using the keyboard 96
Generation random numbers 98
if statement 98
Double equal sign 100
Blocks 100
Indentation in if statement 101
Broken fork (if without else) 101
Conditions with comparison and logical operators 102
Comparison of numbers and symbols 102
Comparison of objects 103
Importing everything at once 105
Logical operators 106
How "zero" differs from "nothing" 108
Conditions in brackets and brackets in conditions 109
Nesting if statements 111
Switch 113
Choice of option 113
Don't forget to include break! 115
String argument - new in Java 7 117

Chapter 6 Cycles 119
while loop 119
for 122 loop
The structure of the for 124 loop
Premiere of the hit “Al in the Rain” 125
cycle do 126
Reading a single character from the keyboard 129
File Manipulation 130
Variable declaration in block 130

Part III. Object Oriented Programming 131

Chapter 7 Classes and Objects 133
Class definition 133
Open Class 135
Declaring Variables and Creating Objects 135
Variable initialization 138
One program is many classes 139
Defining a Method in a Class 139
Account displaying itself 140
Method header 141
Passing Parameters to a Method and Getting a Value from a Method 142
Passing a value to a method 144
Method return value 145
How to make numbers look pretty 147
Access modifiers 151
Proper Programming Style 152
How to make a field inaccessible 154
Validating Rules with Access Methods 156

Chapter 8 Code reuse 157
Class definition 158
Class that defines an employee 158
Proper use of class 159
Creating a payment receipt 161
Working with files (small digression) 162
Storing data in a file 162
Copy and paste code 163
Reading from a file 164
Where did my file go? 166
Adding Folder Names to a File Name 166
Line-by-line reading 167
Inheritance 169
Deriving a class 171
Using Derived Classes 174
Type matching 175
Using the PartTimeEmployee Class 176
Overriding Existing Methods 177
Annotations 179
Calling Methods of Base and Derived Classes 179

Chapter 9 Constructors 181
Constructor definition 181
What is temperature 182
What is the temperature scale 182
So what is temperature? 183
What can be done with a temperature of 185
Finding the right constructor 186
Some things never change 189
Base class constructor in derived class 190
Advanced temperature class 190
Derived Class Constructors 191
Using Enhanced Temperature Class 192
Default Constructor 193
The constructor can not only fill in the fields 194
Classes and Java methods AP 196
@SuppressWarnings annotation 198

Part IV. Advanced Programming Techniques 199

Chapter 10 Proper use of variables and methods 201
Class 201 definition
Another way to make numbers pretty 202
Using the Player 203 class
Nine constructor calls 205
Graphical user interface 205
Let's kick the exception to another method 207
Static fields and methods 207
Why so much static 209
Static initialization 210
Displaying overall team statistics 210
Static import 212
Beware of static! 213
Let's experiment with variables 214
Variable in place 215
Variables in different places 217
Passing parameters 219
Pass by value 219
Return result 221
Pass by reference 221
Returning an object from method 223
Epilogue 224

Chapter 11 Arrays and Collections 225
How to Arrange Items in a Row 225
Creating an array in two steps 227
Saving values ​​228
Tabulostops and others Special symbols 230
Array initialization 230
Extended for loop 231
Search 233
Arrays of objects 236
Using the Room 237 class
Another way to decorate the numbers 240
Ternary conditional operator 241
Arguments command line 241
Using Command Line Arguments in Code 242
Checking the Number of Command Line Arguments 244
Collections 245
Collection classes 246
ArrayList class 247
Using Generic Types 250
Checking if there is more data 250

Chapter 12 How to keep a good face on a bad game 253
Exception Handling 254
catch block parameter 258
Exception types 259
Who should catch exception 261
catch block with multiple exception types 267
Let's not be overly cautious 267
Restoring the program after an exception 268
Our friends are good exceptions 269
Handle the exception or pass it on 270
finally block 274
Closing files 276
How to close file 276
Resources in try block header 276

Chapter 13 Area of ​​visibility 279
Access Modifiers to Class Members 280
Classes, Access, and Program Parts 280
Classes and class members 281
Class Member Access Rules 281
Example with picture in frame 283
Folder structure 285
Create frame 286
How to change the program without changing the classes 287
Default Access 289
How to get into package 292
Secure access 292
Including a non-derived class in the same package 294
Class Access Modifiers 295
Open classes 296
Non-public classes 296

Chapter 14 Responding to keyboard and mouse events 299
Mouse click response 299
Events and event handling 301
Java 302 interfaces
Threads 303
keyword this 304
The body of the actionPerformed() method 305
Version ID 305
Responding to Other Events 306
Internal classes 311

Chapter 15 Applets 315
Example of a simple applet 315
Running Applet 316
Open class 317
Java API classes 317
Animated Applet 318
Methods used in applet 319
Contents of applet methods 320
Responding to events in an applet

Line 16. Database connection 325
JDBC and Java DB 325
Creating database records 326
Using SQL Commands 328
Connecting and disconnecting a database 328
Data Extraction 330

Part V Magnificent Tens 333

Chapter 17. Ten Ways to Avoid Mistakes 335
Proper use of letter case 335
Exit from switch block 336
Comparing Two Values ​​336
Adding an element to the GUI 336
Adding event receivers 337
Defining constructors 337
Fixing non-static links 337
Keeping Array Bounds 337
Pointers to nu 11 338
Help virtual machine Java find classes 338

Chapter 18 Ten Java Sites 341
Websites for this book 341
Java 341 sites
News, reviews, code examples 342
Job 342
Sites for everyone 342

Part VI. Applications 343

Appendix A. Installing the IDE 345
Download and install JDK 345
Download and install Eclipse 349
Configuring the Eclipse 351
Appendix B. Using Eclipse 353
Working with book examples 353
Creating your own project 355
Index 359

Download the book for free 8.23 ​​mb. djvu

Java for dummies. Video

Java is a programming language. It allows programmers to write instructions for a computer using English commands instead of writing in numerical code. Java is a high-level programming language because its code is easy to write and read. Just like regular languages, Java has a set of rules that govern how instructions are written. These rules are called "syntax". The finished high-level Java code is translated into machine-understandable digital code, which is executed by the computer.

Who created the Java programming language?

Java was created in the early 90s by a team of programmers led by James Gosling for Sun Microsystems. Java was originally designed to be developed on mobile devices Oh. But when Java 1.0 was released in 1996, the main focus of the language shifted to use on the web. Java gave more interactivity to users by allowing developers to create animated pages. Over time, Java has become a successful programming language for the web and beyond.

20 years later, Java is still an incredibly popular language with over 6.5 million developers worldwide.

Why choose Java?

Java was built around a few key principles:

1. Ease of use.

The basics of Java are taken from the C++ language. Despite the power of C++, this language has a rather complicated syntax and is inadequate for all the requirements of Java. As Java improved upon the ideas of C++, it provided a programming language that was powerful yet simple.

2. Reliability.

Java minimizes fatal errors due to programmer errors. Thus object-oriented programming was introduced. Once data and actions were collected in one place, the reliability of the Java language improved.

3. Safety.

Since Java was originally designed exclusively for mobile devices that would exchange data over networks, security was at its core from the very beginning. high level. On the this moment Java is probably the most safe language programming.

4. Platform independence.

Programs written in Java had to work no matter what platform they were run on. Java was originally a portable language, for which neither the operating system nor the computer hardware is important.

The Sun Microsystems team has successfully combined key principles. Java owes its popularity to its reliability, security, ease of use, and portability.

Where to start learning Java?

1. Install JDK

To start programming in Java, you need to download and install the Java development Kit (Java Development Kit, JDK). Once you install the JDK on your computer, you can start writing your first program right away.

2. Select IDE

IDE - Integrated Development Environment. There are several different tools for developing applications in Java. Their goal is to help write a Java application. There are several Java development environments, but we recommend NetBeans - perfect for beginners. You can focus on just a couple of NetBeans commands to achieve your goals.

3. First steps

Inevitably, the first program of any beginner is simple program"Hello World", which simply prints the title. This simple program will show you how to compile, run, and run an application in a development environment like NetBeans.

After creating your first program, it's time to start learning the language with lessons for beginners, for example, with courses -. They will guide you through the different stages of learning Java syntax.

Or, if you're the kind of person who likes to jump right into the water, you can start your training in a more ambitious way. The more you dive into the depths of the language, the more you will learn. This can be done by immediately starting to write a Java application.

4. How to choose your first Java application

There is a lot of theory behind any programming language, including Java. You will have to learn the syntax of the language and how the entire application is built. But it seems to us that it is more important to remember that the Java language is needed in order to use it. There are an infinite number of applications that can be created with it. And if you choose from the start what kind of application you want to create, it will dictate the way you learn Java syntax.

Let's say you don't know anything about how to write programs in Java, but you decide to start with a simple calculator. You already know what a calculator is and what it looks like. There are no design questions, there are questions about implementation. You will learn that in the process of creating a program, you will constantly ask yourself questions like "How to do this? .." And there will be many of them. But the more questions you have, the more you will learn about the language.

For example, the first thing you're likely to think of is a GUI (graphical user interface), simply how the program will look on the screen while the application is running. Intuitively, you feel what the program should look like, from your experience with ready-made applications. First, the main window of the program, where all the control elements of the calculator will be located. Buttons for numbers, for operations (addition, multiplication, etc.). Element for displaying the result of calculations. Etc.

So we roughly outlined your first set of questions. How to make an application window? How to add buttons to it? Which element to use to display results? This is where learning the Java language begins. You start looking for answers on how to create a Java application, what elements to use for the application window, what elements to use for buttons, and so on. You will always find answers on sites with Java lessons, in books, on programmer forums.

The most important thing is to do the first work program. Do not think about doing everything optimally right away. This will come with experience as you gain confidence in Java programming. For now, the only goal is to get the Java code to compile and run. Even if the program does not work as intended, it will give rise to learning.

5. Another way

If you feel that you won’t be able to cope with learning a programming language alone, especially one as serious and large-scale as Java, try going to specialized courses where you learn the basics of programming. For instance,