Few words about how to write [disputably] nice code

Июль 22, 2022

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Few words about how to write [disputably] nice code

Содержание

2. Packages Package system - way of hierarchical organization of the project code In Java packages map
3. Package visibility package ru.innopolis.bootcamp2; public class PublicClass { } package ru.innopolis.bootcamp2; class DefaultClass { }
4. Package naming conventions A name for a Java package must be a sequence of one or
5. Packages in file system
6. Build in packages We build and run with respect of the package One class javac ru/innopolis/bootcamp2/BootCampSpecificClass.java
7. Referencing the package
8. Stating coding standards Coding standards - usually internal corporate document helping to organize the code Start
9. Stating coding standards
10. Common rules Each Java source file (.java file) has the following structure: Introductory comments Declaration of
11. What is comment Comment - is a piece of text that do not affect compilation Single
12. Special comments Use “//XXX” in a comment to flag something that is bogus but works Use
13. Special comments
14. Introductory comment (javadoc) /** * @deprecated if you recommend not to use a class * to
15. Introductory comment (javadoc)
16. Introductory comment /* * @(#)Blah.java 1.82 99/03/18 * * Copyright (c) 1994-1999 Sun Microsystems, Inc. *
17. Class/Interface arrangement Instance variables Constructors Methods http://developer.alexanderklimov.ru/android/java/constructor.php
18. Class/Interface arrangement
19. Naming conventions Divided into Conventions about how to give meaningful names Conventions about how names must
20. Class Names (same for interfaces) Should be singular nouns, referring to the object they represent First
21. Method names Verbs or verbal forms in mixed cases Starting with lower letter and each internal
22. Method names Methods returning void should be named with imperative verbs describing what they must do
23. Variables Variables should be named for the objects they represent Usually named with a singular noun
25. Parameter and constant names Name parameters in such a way that the method call is readable
27. Code readability conventions These conventions are often very close to design guidelines, since code readability is
28. Formatting conventions Very important to ease code readability and to make quicker code inspections The specific
29. Formatting conventions One statement per line Use indents to highlight structured programming constructs Do not indent
30. Putting brackets Open brace “{” appears at the end of the same line as the class,
32. Lines and wrapping When an expression will not fit on a single line, break it according
34. Variables declaration There should be usually only one declaration per line to promote comments of the
35. Example of good style http://www.docjar.net/html/api/java/util/Collections.java.html
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Слайд 2

Packages
Package system - way of hierarchical organization of the project code
In

Java packages map to file system.
Each file belonging to a package X.Y.Z:
Should be placed in a folder PROJECT/X/Y/Z
Should have explicit declaration package X.Y.Z;

Слайд 3

Package visibility
package ru.innopolis.bootcamp2;
public class PublicClass { }
package ru.innopolis.bootcamp2;
class DefaultClass { }

Слайд 4

Package naming conventions
A name for a Java package must be a

sequence of one or more valid Java identifiers separated by dots (“.”)
package java.lang;
package java.io;
package java.awt;
package ru.innopolis.iis.mlkr;
Usually, the letters in the name of a package are all lowercase
If a package is to be widely distributed, it is a common convention to prefix its name with the reverse Internet domain name of the producing or distributing organization, with slashes substituted by dots.

Слайд 5

Packages in file system

Слайд 6

Build in packages
We build and run with respect of the package
One

class
javac ru/innopolis/bootcamp2/BootCampSpecificClass.java
cd ru/innopolis/bootcamp2 javac BootCampSpecificClass.java
java ru/innopolis/bootcamp2/BootCampSpecificClass
java DefaultClass
All classes in package
javac ru/innopolis/bootcamp2/*.java
All classes recursively (build tree)
Ant, Maven

Слайд 7

Referencing the package

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Stating coding standards
Coding standards - usually internal corporate document helping to

organize the code
Start from Java Code Conventions
Keep it simple (less than 20 rules)
Better if developed by the team
Be not too specific
Avoid bad standards
Evolve it over time

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Stating coding standards

Слайд 10

Common rules
Each Java source file (.java file) has the following structure:
Introductory

comments
Declaration of package (if needed)
Import instruction (if needed)
Definition of classes and interfaces (in Java you can store single class* in a file)

Слайд 11

What is comment
Comment - is a piece of text that do

not affect compilation
Single line:
// something will happen here
int x = 4; //TODO: implement calculation of x!
Multiple lines (inline):
obj.callSomeMethod(a /* very important param */, b, c);
/* this is
Very long
Multiline
Comment */

Слайд 12

Special comments
Use “//XXX” in a comment to flag something that is

bogus but works
Use “//FIXME” to flag something that is bogus and broken
Use “//TODO” to flag something that should be implemented

Слайд 13

Special comments

Слайд 14

Introductory comment (javadoc)
/**
* @deprecated if you recommend not to use

a class
* to preserve backward compatibility
*
* @see OtherClass
*
* @serial SERIAL_NUMBER
*
* @since WHICH.VERSION.OF.THE.PROJECT/LIBRARY
*
* @version 1.0.0.1
*
* @author Stanislav Protasov
*/
*Javadoc support html

http://www.codenet.ru/webmast/java/JavaDoc/

Слайд 15

Introductory comment (javadoc)

Слайд 16

Introductory comment
/*
* @(#)Blah.java 1.82 99/03/18
*
* Copyright (c) 1994-1999 Sun Microsystems, Inc.
*

901 San Antonio Road, Palo Alto, California,
* 94303, U.S.A. All rights reserved.
*
* This software is the confidential and
* proprietary information of Sun Microsystems,
* Inc. ("Confidential Information"). You shall
* not disclose such Confidential Information and
* shall use it only in accordance with the terms
* of the license agreement you entered into
* with Sun.
*/

Слайд 17

Class/Interface arrangement
Instance variables
Constructors
Methods
http://developer.alexanderklimov.ru/android/java/constructor.php

Слайд 18

Class/Interface arrangement

Слайд 19

Naming conventions
Divided into
Conventions about how to give meaningful names
Conventions about how

names must be written
All of the names in your program should convey information about the purpose of the item they refer
Use not abbreviations for your names (only if they are in common use in normal speech)
Use descriptively named variables
Avoid ambiguous words

Слайд 20

Class Names (same for interfaces)
Should be singular nouns, referring to the

object they represent
First letter and each internal word of class or interface names is capitalized (UpperCamelCase)
Train, Event, Station
Do not put hierarchy information in class names, unless real-world names bear this information
EmployeePerson, SecretaryEmployeePerson

Слайд 21

Method names
Verbs or verbal forms in mixed cases
Starting with lower letter

and each internal word should be capitalized (lowerCamelCase)
Methods returning a boolean usually named with verb phrases expressing the question
isRed()
Methods assigning boolean variable can be named with verb phrases beginning with "set"/"be"
beOff(), setStateOffline()

Слайд 22

Method names
Methods returning void should be named with imperative verbs describing

what they must do
openDBLink()
Methods converting a value into another should be named with verb phrases starting with "as"/"to" and
denoting the converted type
asDecimal(), toString()
Other methods should describe what they return
previousSignal()
Accessor methods may report the variable’s name prefixed with “get” or “set”

Слайд 23

Variables
Variables should be named for the objects they represent
Usually named with

a singular noun
If it represent a collection of objects, its name should be plural
The name should not include typing information
lowerCamelCase
One lowercase letter variable names are OK only for temporary variables, indexes, etc.

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Parameter and constant names
Name parameters in such a way that the

method call is readable
public static double power(double base, double exponent) {
//
}
Use named constants and not literal values, wherever a specific value is needed
In order to differentiate the names of constants from the other names, constants are often completely capitalized and compound names are separated by an underscore

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Code readability conventions
These conventions are often very close to design guidelines,

since code readability is obtained with cohesive classes and methods
Classes and methods focused on performing a single task
Methods must be short
In Java standard less than 10 statements
Every method performs just one task, and
Every full method must fit on one screen

Слайд 28

Formatting conventions
Very important to ease code readability and to make quicker

code inspections
The specific code convention adopted is less important than sticking to the same convention throughout the code
NetBeans: Alt + Shift + F
Eclipse: Ctrl/Cmd + Shift + F

Слайд 29

Formatting conventions
One statement per line
Use indents to highlight structured programming constructs
Do

not indent too much…do not waste horizontal space!
Do not indent too little…make the structure evident!

Слайд 30

Putting brackets
Open brace “{” appears at the end of the same

line as the class, interface, or method declaration
Closing brace “}” starts a line by itself aligned with the opening statement, except null block “{}”
No space between a method name and the parenthesis “(” starting its parameter list
Methods are separated by a blank line
When a nested statements occur within blocks
Use the 4 spaces rule, in general

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Lines and wrapping
When an expression will not fit on a single

line, break it according to these general principles:
Break after a comma.
Break before an operator.
Prefer higher-level breaks to lower-level breaks.
Align the new line with the beginning of the expression at the same level on the previous line.
If the above rules lead to confusing code or to code that's squished up against the right margin, just indent 8 spaces instead.

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Variables declaration
There should be usually only one declaration per line to

promote comments of the variables
Variables should be initialized where they are declared…
Unless the value of the variable depends on some computations to be performed later
Declarations should be placed at the beginning of the outermost block where a variable is used
Avoid declarations in inner blocks of variables with the same name as variable in outer blocks

Слайд 35

Few words about how to write [disputably] nice code

Содержание

PackagesPackage system - way of hierarchical organization of the project codeIn

Package visibilitypackage ru.innopolis.bootcamp2;public class PublicClass { }package ru.innopolis.bootcamp2;class DefaultClass { }

Package naming conventionsA name for a Java package must be a

Packages in file system

Build in packagesWe build and run with respect of the packageOne

Referencing the package

Stating coding standardsCoding standards - usually internal corporate document helping to

Stating coding standards

Common rulesEach Java source file (.java file) has the following structure:Introductory

What is commentComment - is a piece of text that do

Special commentsUse “//XXX” in a comment to flag something that is

Special comments

Introductory comment (javadoc)/** * @deprecated if you recommend not to use

Introductory comment (javadoc)

Introductory comment/** @(#)Blah.java 1.82 99/03/18** Copyright (c) 1994-1999 Sun Microsystems, Inc.*

Class/Interface arrangementInstance variablesConstructorsMethodshttp://developer.alexanderklimov.ru/android/java/constructor.php

Class/Interface arrangement

Naming conventionsDivided intoConventions about how to give meaningful namesConventions about how

Class Names (same for interfaces)Should be singular nouns, referring to the

Method namesVerbs or verbal forms in mixed casesStarting with lower letter

Method namesMethods returning void should be named with imperative verbs describing

VariablesVariables should be named for the objects they representUsually named with

Parameter and constant namesName parameters in such a way that the

Code readability conventionsThese conventions are often very close to design guidelines,

Formatting conventionsVery important to ease code readability and to make quicker

Formatting conventionsOne statement per lineUse indents to highlight structured programming constructsDo

Putting bracketsOpen brace “{” appears at the end of the same

Lines and wrappingWhen an expression will not fit on a single

Variables declarationThere should be usually only one declaration per line to

Example of good stylehttp://www.docjar.net/html/api/java/util/Collections.java.html

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