Coding guidelines

Project structure

File naming

• Class Naming: Class names are written in ​UpperCamelCase

  ​SignInActivity,​SignInFragment

• Class Type: mention type of class in name like:

  • Button- ​

    btn_send_pressed.png

  • Adapters - ​

    LocationSearchAdapter, AddDataSetListener

  • Interface/Callbacks - ​

    OnLocationSetListener

  • Utils class -

    ValidationUtils, FirebaseUtils

• Resource files mention type of resource as prefix like:

  • Button- ​

    btn_send_pressed.png

  • Icons- ​

    ic_star.png

  • Launcher icons-

    ic_launcher_calendar.png

  • Menu- ​

    menu_submenu_bg.png

  • Selector state- ICONNAME_STATENAME like

    btn_order_pressed.png

• Layout files mention Type of components where they are being used with its usage like:

  • Activity ​

    activity_user_profile.xml

  • Dialog ​

    dialog_change_password.xml

  • Adapters Item ​

    item_contacts.xml

  • Toolbar ​

    toolbar_custom.xml

Java codes

Variable Declaration

• Member variables Naming: variables name start with m
  • String name ​ : mStrName;
  • TexView textViewName : ​mTvName;
• FINAL variables Naming: variables name in UPPER_CASE

  public ​​static ​​final​​ int ​​SOME​_CONSTANT​=​​42​;

• Android constants/keys naming with prefix:
  • SharedPreferences PREF_
  • Bundle BUNDLE_
  • Intent Extra EXTRA_

Logical codes

• Don't ignore exceptions

  void​ setServerPort(String value) {
     try​​{
        serverPort =​​Integer.​parseInt(value);​
     }catch​​(NumberFormatException e){ 
        // Appropriate Message to user or error handling 
     }
  }
  

• Don't catch generic exception

  try​{
     someComplicatedIOFunction();   ​    // may throw IOException
     someComplicatedParsingFunction();  ​// may throw ParsingException
     someComplicatedSecurityFunction(); //​ may throw SecurityException
                                    
  } catch​​(Exception e) {	              //​ I'll just catch all exceptions
     handleError();	              //​ with one generic handler!
  }
  

• Braces standard braces alignment

  public void method() 
  {
      if (condition()) {
        try {
          something();
        } catch (ProblemException e) {
          recover();
        }
      } else if (otherCondition()) {
        somethingElse();
      } else {
        lastThing();
      }
  }
  

• Mention access specifier

  private​​ int ​​mTotal​=​​0​;

• Activity life-cycle order

  public ​class ​​MainActivity ​​extends​​ Activity​​{
   //Order matches Activity lifecycle
  
  @Override​
  public​​ void​​ onCreate​()​ {}
  
  @Override​
  public​​ void​​ onResume​()​ {}
  
  @Override​
  public ​​void ​​onPause​()​ {}
  
  @Override​
  public​​ void​​ onDestroy​()​ {}
  
  }
  

• App Global Constants

  • Use AppConstants.java for constant/final values

    public class AppConstants {
       /*API SERVER URL*/
       public static String BASE_URL="http://server.com/api/v1/";
       public static String SIGNUP_URL=BASE_URL+"register";
    
       public static String CONTENT_TYPE="application/json; charset=utf-8";
        /*JSON Parsing keys*/
       public static String KEY_PHONE="phone";
       public static String KEY_NAME="name";
    }
    

  • Avoid writing each line of code within onCreate() or any function divide it in functions

    @Override
    protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_profile);
       findAllViews();
       initialize();
       getProfileData(userId);
    }
    

  • Make app functionality in modules

  • Create and use requestCode and resultCode for onActivityResult() e.g

    private int final REQUEST_CAMERA=1;

  • Use InBuild resultCode

    Activity.RESULT_OK

  • And in onRequestPermissionsResult()

    private int final REQUEST_STORAGE_PERMISSION=1;

• Use Java and Android API’s e.g

 ArrayList<String> nameList;
 Collections.sort(nameList);
 Collections.binarySearch(nameList,"David");
 Collections.fill(nameList,"N/A");

XML codes

• **Use self closing tags **

<TextView​
android:id="@+id/text​_view_profile"
android:layout_width="wrap​_content"
android:layout_height="wrap​_content"​/>

• **ID naming **

  android:id="@+id/imgProfile"

Espresso tests

• Every Espresso test class usually targets an Activity, therefore the name should match the name of the targeted Activity followed by ​Test,.

  SignInActivityTest