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JAVA Coding Pattern

코딩 규칙

2010.08.03 박혜웅

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• 이 문서는 권고안의 내용중 중요한 부분과 개인경험을 통해 정리하였다 .• Sun 의 권고안

– http://java.sun.com/docs/codeconv/– http://www.oracle.com/technetwork/java/codeconv-138413.html

• 권고안을 따르는 Eclipse default formatter 를 기준으로 한다 .

Code Conventions-Basic

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• File Type– .java (UTF-8)– .class– README

• 설명을 위한 텍스트 파일 (UTF-8)

• Beginning Comments– ??

• Class and Interface Declarations– Variables, Method

• public, protected, private 순서로 나열• Indentation

– tabs only (4 spaces), Eclipse default formatter 와 동일• Line Length

– 80 ~ 150 ( 모니터에 맞게 )• Wrapping Lines ( 줄 바꿈 )

– Eclipse default formatter 와 동일

Code Conventions

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• Block Comments, Single-Line comments, Trailing Comments (/* */)– Do not use for commenting code.

• Search 명령의 검색결과가 소스인지 코멘트인지 불분명하므로 .

• End-Of-Line Comments (//)– Use for commenting code.

Code Conventions-Comments

//if (bar > 1 ) {//// // To do:// ...//}// else// return false;

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• One declaration per line– Eclipse default formatter 와 동일

• Avoid declarations that hide declaratioins.– 동일한 변수명을 가능한 사용하지 말아라– 단 , Constructor, Setter, Getter 는 예외다 .

Code Conventions-Declarations

int level; // Goodint size; // Good

int level, size; // Avoid

int count;...func() {

if (condition) {int count; //

Avoid...

int count;...func() {

if (...) {int countSome;...

int count;...setCount(int count) {

if (...) {this.count=count;

...

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• Class and Interface Declarations– Eclipse default formatter 와 동일– Methods are separated by blank line

Code Conventions-Declarations

class Sample extends Object {int ivar1;int ivar2;

Sample(int i, int j){ivar1=i;ivar2=j;

}

int emptyMethod() {}

...}

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• Simple Statements– Each line should contain at most one statement

– Do not use the comma operator

• return Statements– Use simple expression

– Do not use ternary expression (?)

Code Conventions-Statements

argv++;argc--;

argv++; argc--; // Avoid

System.out.println("error");System.exit(1);

System.out.println("error"), System.exit(1);// Avoid

return: myDisk.size();

return (size ? size : defaultSize); // Avoid

if( size > 0 ) {return size;

}return 0;

return;

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• if-else Statements– if statements always use braces {}.

• for, while Statements– An empty for, whlie statement should have the following form

• Blank Lines, Blank Spaces– Eclipse default formatter

Code Conventions-Statements, Blank

if ( condition ) {statement;

}

if ( condition ) // Avoidstatement;

for ( initialization; condition; update );while ( condition );

for ( initialization; condition; update ) {} ; //Avoidwhile ( condition ) {}; //Avoid

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• Java Project(?), Classes, Interfaces Naming– Should be noun with the first letter capitalized.– Avoid acronyms( 머리글자어 ) and abbreviatioins( 약어 ) except URL,

HTML...– Example

• class URLEncoder;• interface Storing;

– Use Whole words.– Example

• class MatrixCalculation; // OK• class MatCalc; // AVOID!

• Methods– Should be verbs with the first letter lowercase.– Omit class or interface name.– Example

• MatrixCalculation calculation = new MatrixCaculation();• calculation.getData(); // OK• calculation.getMatrixCalculationData(); // AVOID!

Code Conventions-Naming

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• Variables– Should be noun with the first letter lowercase. – If instance variable(public, protected, private, default), always use

keyword “this”.– Example

• private long instanceVariable;• this.instanceVariable = 10L; // OK• instanceVariable = 10L; // AVOID!

– Avoid acronyms( 머리글자어 ) and abbreviatioins( 약어 )– Example

• BufferedReader bufferedReader = new BufferedReader(); // OK• BufferedReader reader = new BufferedReader(); // OK• BufferedReader br = new BufferedReader(); //AVOID!

– if name is so long, can be shortten.– Example

• int difference; // OK• int diff; // OK• int d; // AVOID

Code Conventions-Naming

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• Constants (static final)– Should be all uppercase with words separated by underscores(_).– Ends with noun.– Example

• static final int MIN_WIDTH = 4; // OK• static final int minWidth = 4; // AVOID!

Code Conventions-Naming

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• Referring to Class Variables and Methods– Avoid using an object to access a static variable or method.– Example

• AClass.classMethod(); // OK• anObject.classMethod(); // AVOID!

• Variable Assignments– Avoid assigning several variables to the same value in a single state-

ment.– Example

• fooBar.fChar = barFoo.lchar = ‘c’; //AVOID!• d = (a = b + c) + r; //AVOID!

• Parenthese( 소괄호 )– Use parentheses liberally.– Example

• if(a == b && c == d) //AVOID!• if((a ==b) && (c == d)) // OK

Code Conventions-Programming