Notes on Udacity Developing Android Apps

Notes as I follow through with Udacity's online course Developing Android Apps.

The discussion forum provides a place for discussions.

Declaring layouts: android

To use Fragment class, it depends on the Android version;
import android.app.Fragment (requires API 11 and above)
import android.support.v4.app.Fragment; (requires API 10 and above)

Application Lifecycle

Activity between states.

Activity Lifecycle

When app starts the activity;
Sequence onCreate - onStart - onResume

When rotating the device
Sequence onPause - onStop - onDestroy - onCreate - onStart - onResume

Toast

Verify data contents with Toast. Within the fragment to be executed, use;

Toast toast = Toast.makeText(getContext(), "you did a click", Toast.LENGTH_SHORT );
toast.show();

Networking

The Uri.Builder helps construct http and https URLs.

e.g. 1

Uri.Builder builder= new Uri.Builder();
builder.scheme("http")
        .authority("api.openweathermap.org")
        .appendPath("data")
        .appendPath("2.5")
        .appendPath("forecast")
        .appendPath("daily")
        .appendQueryParameter("q", city)
        .appendQueryParameter("mode","json")
        .appendQueryParameter("units","metric")
        .appendQueryParameter("cnt","7");

e.g. 2

final String FORECAST_BASE_URL="http://api.openweathermap.org/data/2.5/forecast/daily?";

builder= new Uri.Builder();
builder.parse(FORECASE_BASE_URL).buildUpon()        
        .appendQueryParameter("q", param[0])
        .appendQueryParameter("mode","json")
        .appendQueryParameter("units","metric")
        .appendQueryParameter("cnt","7");

Test JSON
https://jsonformatter.curiousconcept.com/

Android Permissions

Permissions needed
https://developer.android.com/reference/android/Manifest.permission.html

Thread

AsyncTask class simplify background thread creation and UI thread synchroization.
http://developer.android.com/guide/components/processes-and-threads.html

Getting the sample codes

Using git;
git clone https://github.com/udacity/Sunshine-Version-2.git
cd Sunshine-Version-2
// Show all branches
git branch -a
// Show only remote branches
git branch -r

git checkout 1.06_attach_adapter

Open Weather JSON

JSON URL samples
http://api.openweathermap.org/data/2.5/weather?q=Port%20Dickson

http://api.openweathermap.org/data/2.5/weather?q=Kuala%20Lumpur&units=metric&cnt=5&mode=json

URL query for Sunshine app
requirements: 1 week, JSON format, city, metric

Geonames JSON site at http://www.geonames.org/export/ws-overview.html

Android Studio 1.4 Keyboard Shortcuts

Ctrl+q View quick documentation
Ctrl+o List members of a class to populate in source
Shift+F6 Rename class, methods and variables with corrections to all places they are used (refactor)
Ctrl+o Override methods of base class
Ctrl+i Implement methods of base class

GIT references

https://git-scm.com/docs/git-show-branch

Backup source files
git archive --format zip --output ../chapter1.zip 1.06_attach_adapter