Download Conding Convention for Android_v1.0

Conding Convention
For Android
Conductor: ThuongNV
Version: 1.0
Reference:
• Java Coding convention of Fsoft
• http://developer.android.com/guide/index.html
Content
• Standard Java coding convention
• Icon design guidelines on Android
• Designing for Performance on Android
Standard Java Coding convention
 General rule
 Naming convention
 Java source files
 Comment code
 Declarations
General rule
 Simple
 Precise
Naming convention
 Names should be functionally meaningful.
 Identifiers must be as short as possible (<=20 character).
 Avoid names that are similar or differ only in case.
Ex: persistentObject and persistentObjects
 Avoid cryptic names
 Abbreviations in names should be avoided.
computeAverage(); // NOT: compAvg();
generateHTML();
// NOT: generateHypertextMarkupLanguage();
 The method name should not contain any special
characters other than underscore (_).
Naming convention
 Class/Interface name must start with uppercase
 Variable name must start with lowercase
 Package name must be lowercase.

Ex: com.fsoft.atravel.activity
 Constants:


All constants to be named in uppercase letters, with underscore
between words.
All constants must be declared as static final.
 Method:


Method name must start with lowercase letter.
Usually use “active verb” as the first word of method name
isActive, hasAddresses
 getNewData, showMap

Java source file
 Java source files have the following ordering:
 Beginning comments
 Package and Import statements
 Class and interface declarations
Java source file example
/*
* Classname
*
* Version information
*
* Date
*
* Copyright notice
*
* Modification Logs:
* DATE
AUTHOR DESCRIPTION
* -------------------------------------------------------* 10-Aug-2003 CuongDD Description of modification
*/
package com.fsdn.atravel.activity;
import java.util.ArrayList;
public class ClassName{
// class content
}
Comment code
 Block Comments
/*
* Here is a block comment.
*/
 Single-Line Comments
if (condition) {
// Handle the condition.
...
}
 Trailing Comments
if (a == 2) {
return TRUE;
}
// special case
 End-Of-Line Comments
//if (bar > 1) {
// // Do something.
Declaration
 One declaration per line is recommended since it
encourages commenting
int level; // indentation level
int size; // size of table
 Array Declaration
int anIntArray[]; // AVOID
int[] anIntArray; // RECOMMENDED
 Initialize local variables where they're declared
 Using try-catch statement
Declaration
 Braces “{}” are used around all statements, even single
statements, when they are part of a control structure,
such as:



if-else
for statement
while statement
if (condition) //AVOID! THIS OMITS THE BRACES {}!
statement;
if (condition) { // RECOMMENDED
statement;
}
Content
• Standard Java coding convention
• Icon design guidelines on Android
• Designing for Performance on Android
Icon design guideline
 Using the Android Icon Templates Pack
 Providing Density-Specific Icon Sets
Icon design guideline(cont.)
 Use common naming conventions for icon assets
Icon design guideline (cont.)
 Set up a working space that organizes files for
multiple densities
assets/...
ldpi/...
_pre_production/...
working_file.psd
finished_asset.png
mdpi/...
_pre_production/...
working_file.psd
finished_asset.png
hdpi/...
_pre_production/...
working_file.psd
finished_asset.png
res/...
drawable-ldpi/...
finished_asset.png
drawable-mdpi/...
finished_asset.png
drawable-hdpi/...
finished_asset.png
Icon design guideline (cont.)
 When saving image assets, remove unnecessary
metadata:
Ex: To remove the Photoshop header, follow these
steps:



Under the File menu, choose the Save for Web & Devices
command
On the "Save for Web & Devices" panel, set the Preset pop-up
to "PNG-24," set the pop-up under Presets to "PNG-24" as
well, and select the Transparency box (if the image uses
transparency)
Select Save.
Content
• Standard Java coding convention
• Icon design guidelines on Android
• Designing for Performance on Android
Designing for Performance
 Avoid Creating Objects
 Example 1:
System.out.println(txtEmail.getText().toString());
 String temp = txtEmail.getText().toString();
System.out.println(temp);


Example 2: Slice up multidimensional arrays into parallel
single one-dimension arrays.
An array of ints is a much better than an array of Integers.
 Two parallel arrays of ints are also a lot more efficient than an
array of (int,int) objects.

Designing for Performance(cont.)
 Avoid internal getters/setters
 Use static final for constants
 Use "for-each" loop syntax. For example:
static class Foo {
int mSplat;
}
Foo[] mArray = …
Slowest:
public void zero() {
int sum = 0;
for (int i = 0; i < mArray.length; ++i) {
sum += mArray[i].mSplat;
}
}
Fastest:
public void two() {
int sum = 0;
for (Foo a : mArray) {
sum += a.mSplat;
}
}
Question & Answer