In this chapter we review the basic rules and recommendations for writing quality program code. We pay attention to naming the identifiers in the program (variables, methods, parameters, classes, etc.), formatting and code organization rules, good practices for composing methods, and principles for writing quality documentation.

1. Java Best Practices
Naming Conventions, Build
Automation Tools and Functional
Interfaces
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Technical Trainers
Software University
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1. Naming conventions
1. File Naming, Class Naming
2. JAR Files
3. Code Conventions
2. Java Documentation
3. Build Automation
1. Tools
2. Maven Examples
4. Functional Interfaces
Table of Contents

3. Naming Conventions

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 JAR files names should consist of single word or several words
separated by hyphen
 Can contain version information
 Examples:
 xalan25.jar
 ant-apache-log4j.jar
 Incorrect examples:
 Ant.Apache.Log4J.jar
 Oracle.JDBC.Drivers.jar
Naming JAR Files in Java

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 Microsoft official C# code conventions
 Design Guidelines for Developing Class Libraries:
http://msdn.microsoft.com/en-us/library/ms229042.aspx
 Java official code conventions
 http://www.oracle.com/technetwork/java/codeconvtoc-136057.html
 Semi-official JavaScript code conventions
 http://javascript.crockford.com/code.html,
http://google-styleguide.googlecode.com/svn/trunk/javascriptguide.xml
 Semi-official PHP conventions
 http://www.php-fig.org/psr/psr-1/
Code Conventions

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 In C# use single [Tab] after breaking a long line:
 In JavaScript, Java and PHP use double [Tab] in the carried long lines:
Breaking Long Lines in C#, JavaScript,
Java and PHP
if (matrix[x, y] == 0 || matrix[x-1, y] == 0 ||
matrix[x+1, y] == 0 || matrix[x, y-1] == 0 ||
matrix[x, y+1] == 0)
{
matrix[x, y] == 1;
}
if (matrix[x, y] == 0 || matrix[x-1, y] == 0 ||
matrix[x+1, y] == 0 || matrix[x, y-1] == 0 ||
matrix[x, y+1] == 0) {
matrix[x, y] == 1;
}

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 Packages naming guidelines
 Use camelCase
 Following formats are acceptable:
 com . company . product . component . …
 product . component . …
 Example:
 com.apple.quicktime, hibernate.core
 Incorrect examples:
 IBM.DB2.Data, ibm.db2_data, Tetris.UI
Naming Java Packages / JS Namespaces

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 Files with source code should have names matching their
content
 File containing a class Student should be names
Student.cs / Student.java / Student.php
 Example:
 StudentDAO.cs, Constants.java,
CryptographyAlgorithms.cs
 Incorrect examples:
 Program.cs, SourceCode.java, _d2.cs,
WebApplication1.jsp, Page1.aspx
Naming Files in C#, Java and PHP

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 Several formats are acceptable:
 [Noun] or [Verb] or [Adjective]
 Use PascalCase for the enumeration and
CAPITALS for its members
 Examples:
 enum Suit {CLUBS, DIAMONDS, HEARTS, SPADES},
enum Color {RED, GREEN, BLUE, …}
 Incorrect examples:
 enum Color {red, green, blue, white},
enum PAGE_FORMAT {A4, A5, A3, LEGAL, …}
Naming Enumerations in Java and JS

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 Following formats are acceptable:
 [Verb] + 'able'
 [Noun], [Adjective] + [Noun]
 Examples:
 Serializable, Enumerable, Comparable,
Runnable, CharSequence, OutputStream
 Incorrect examples:
 list, FindUsers, Run, Inumber, OPTIMIZER,
IMemoryOptimize, FastFindInDatabase
Naming Interfaces in Java

11. JavaDoc Documentation

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 In Java you can document the code using the built-in JavaDoc tool
 JavaDoc tags are preceded by @ "at"
 You can use HTML tags in the documentation code
 For example:
JavaDoc Documentation
/**
* This method returns the sum of two numbers
* @param num1 The first number to sum
* @param num2 The second number to sum
* @return The sum of the two numbers
*/
public static int sumTwoNumbers(int num1, int num2) {
}

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 The summary is exactly after the opening "/**" JavaDoc comment
 Some JavaDoc Tags:
 @param - method parameter
 @author - author of the class
 @return - method return value
 @throws/@exception - exceptions that method throws
 {@code } - source code
 @see - reference to other class similar to this
JavaDoc Documentation Tags

14. Build Automation

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 Build automation is the act of automating a wide variety of tasks
in the developer’s day-to-day activities
 Compiling
 Resolving dependencies
 Packaging
 Deploying
 Running automated tests
Build Automation

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 In the Java world there are three widely-spread build
automation tools
 Apache Ant
 Apache Maven
 Gradle (on Groovy)
Build Automation (2)

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Maven Project Initiation
 Initiating a Maven project consists of declaring the
 Group ID
 Project unique name e.g. org.apache.commons
 Artifact ID
 Produced binary e.g. jar without version e.g. commons
 Version
 Version like 1.0, 1.5 etc.

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Maven Project Structure
src/main/java Application/Library sources
src/main/resources Application/Library resources
src/main/filters Resource filter files
src/main/webapp Web application sources
src/test/java Test sources
src/test/resources Test resources
src/test/filters Test resource filter files
src/it Integration Tests (primarily for plugins)
src/assembly Assembly descriptors
src/site Site
LICENSE.txt Project's license
NOTICE.txt
Notices and attributions required by libraries
that the project depends on
README.txt Project's readme

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Maven POM
 POM.xml is the main configuration where it all starts from
 There is described
 How software is built
 Software’s dependencies

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Maven POM (2)
<project>
<!-- model version is always 4.0.0 for Maven 2.x POMs -->
<modelVersion>4.0.0</modelVersion>
<!-- project coordinates, i.e. a group of values which uniquely identify this project -->
<groupId>com.mycompany.app</groupId>
<artifactId>my-app</artifactId>
<version>1.0</version>
<!-- library dependencies -->
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
</dependency>
</dependencies>
</project>

21. Maven
Live Demo

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 Naming Conventions
 Project Structures
 JavaDoc
 Build Automation
Summary

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Java Best Practices
https://softuni.bg/courses/java-basics/

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 This course (slides, examples, demos, videos, homework, etc.)
is licensed under the "Creative Commons Attribution-
NonCommercial-ShareAlike 4.0 International" license
 Attribution: this work may contain portions from
 "Fundamentals of Computer Programming with Java" book by Svetlin Nakov & Co. under CC-BY-SA license
 "C# Basics" course by Software University under CC-BY-NC-SA license
License

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