426-020222

Feb 02., 2022 -- Planning, JSON, File

Outline

Planning for Quiz Exercise
A Weather App
OpenWeatherMap API
JSON
Simple JSON Parser
Parse JSON from OpenWeatherMap
External Library in Android
File Reader

Planning for Quiz Exercise

Ex01 P01-FontCase
- Checklist
- Google, toy, solve, save
- ONE at a TIME
- Try no debug

Plan

done	Create an Android App from Your A04-BBMF app
easy	Rename the app name to P01-FontCase to change the Title in display. Title only, which shown 		in the image as title "P01-FontCase". The app, folder, package, etc. remains the same.
		The app consists of 1 TextView, 1 EditText, 2 Buttons, FAB and Menu
easy 	Menu has 3 items: Upper, Lower, Reset
google	When launched, textview has font size 32dp, has to be set in JAVA, not in XML

		When EditText content updates, also update the TextView, this can be done in one of 3 ways.  		You may assume the input is always valid.
		Update while typing => 2 extra credit
		By press return key => full credit
NOW		Or another button called "update" => 2 points deduction
google	When Upper button or menu item ToUpper selected, change TextView content to UpperCase letters
		When Lower button or menu item ToLower selected, change TextView content to LowerCase letters
		When FAB or menu item RESET is pressed, restore to original setting

ONE at a TIME

done	Create an Android App from Your A04-BBMF app
easy	Rename the app name to P01-FontCase to change the Title in display. Title only, which shown 		in the image as title "P01-FontCase". The app, folder, package, etc. remains the same.
strings.xml

		The app consists of 1 TextView, 1 EditText, 2 Buttons, FAB and Menu
add edittext, constraints

easy 	Menu has 3 items: Upper, Lower, Reset
string.xml

google	When launched, textview has font size 32dp, has to be set in JAVA, not in XML
		"android textview set font size" programmatically
		https://android--examples.blogspot.com/2015/01/textview-font-size-in-android.html
		tv7.setTextSize(TypedValue.COMPLEX_UNIT_SP,50);

		When EditText content updates, also update the TextView, this can be done in one of 3 ways.  		You may assume the input is always valid.
		Update while typing => 2 extra credit
		By press return key => full credit
NOW		Or another button called "update" => 2 points deduction
		.getText() .setText()


google	When Upper button or menu item ToUpper selected, change TextView content to UpperCase letters
		"android textview text uppercase" programmatically
		https://stackoverflow.com/questions/12159342/set-upper-case-for-textview/12159375
		.toUpperCase()
		
		When Lower button or menu item ToLower selected, change TextView content to LowerCase letters
		When FAB or menu item RESET is pressed, restore to original setting 


		"android textview keyboard enter update"
		https://stackoverflow.com/questions/1489852/android-handle-enter-in-an-edittext
		edittext.setOnKeyListener(new OnKeyListener() {
		    public boolean onKey(View v, int keyCode, KeyEvent event) {
				if ((event.getAction() == KeyEvent.ACTION_DOWN) &&
				            (keyCode == KeyEvent.KEYCODE_ENTER)) {

A Weather App

Best Way to Become Android Developer – A Complete Roadmap
Apply 'demand driven' learning
Build an Android App similar to the iOS stock Weather App.
Functions of the app
- Two (actually more) screens
- Screen One - City List
  - List of cities with city name, zip, and current temp
  - Press add button to add a city by zip/name search
  - Swipe to remove a city
  - C/F switch button
  - Press city will enter Screen Two
- Screen Two - Weather Info
  - City name, current condition and temp
  - Day info, high and low
  - Sliding hourly forcast
  - Five-day forcast
  - Swipe to switch cities
  - Press list button will enter Screen One
Sketchy Challenge List
- Layout
- Weather API
- Internet
- List View
- Multi Screen
- Navigation
- More
A Simplify version of iOS Weather App
- No hourly forcast
- Three day forcast instead of five
- Sol for iOS app as template
Get ideas from online
Few good Android Weather Apps, here, here, and here

OpenWeatherMap API

There are many free weather APIs
Sol° uses the OpenWeatherMap API for all of its weather data
You have to sign up and obtain an API key
Data in JSON format

Current weather data -- http://api.openweathermap.org/data/2.5/weather?zip=94040,us&APPID=YOUR_ID

{
"coord":{"lon":-122.08,"lat":37.39},
"weather":[{
	"id":800,"main":"Clear","description":"clear sky","icon":"01n"
		}],
"base":"stations",
"main":{
	"temp":285.53,"pressure":1019.3,"humidity":86,"temp_min":284.26,"temp_max":287.59
		},
"wind":{
	"speed":0.47,"deg":316.501
		},
"rain":{},
"clouds":{"all":0},
"dt":1474723183,
"sys":{
	"type":3,"id":1442728390,"message":0.0215,"country":"US","sunrise":1474725529,"sunset":1474768821
	},
"id":5375480,
"name":"Mountain View",
"cod":200
}

JSON

JSON stands for JavaScript Object Notation
JSON is a text format for storing and transporting data
OpenWeatherMap returns in JSON format
Learn JSON Yourself in 10 minutes
Andrid Studio has built-in JSON Parser

Simple JSON Parser

A09-JSON-ver01

A simple JSON ZIP parser

{
"country":"US",
"state":"MI",
"city":"YPSILANTI"
}

JSON Format and Parser -- excellent tutorial at TutorialPoint
- JSON Elements -- Array, Objects, Key, Value
- JSON Parsing -- getJSONObject(), then getXXXXX()

Parse

import org.json.JSONException;
import org.json.JSONObject;

public class MainActivity extends AppCompatActivity {
    private ActivityMainBinding binding;
    final String json = "{\"country\":\"US\",\"state\":\"MI\",\"city\":\"YPSILANTI\"}";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
	...
	binding.button.setOnClickListener(	
	...
	binding.textview.setText( "JSON->" + json + "\n\n" + parseJson(json) );
	
    // http://ziptasticapi.com/48197
    // {"country":"US","state":"MI","city":"YPSILANTI"}
    private String parseJson(String input) {
        String output = "Error parsing Json";
        try {
            JSONObject jsonRootObject = new JSONObject(input);

            String city = jsonRootObject.optString("city").toString(); // Ypsilanti
            String state = jsonRootObject.optString("state").toString(); // MI
            output = "Address -> " + city + " , " + state;

        } catch (JSONException e) {
            e.printStackTrace();
        }
        return output;
    }

Parse JSON from OpenWeatherMap

A09-JSON-ver02

JSON data as String

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;	
	
    private ActivityMainBinding binding;
    final String json = "{\"coord\":{\"lon\":-78.7492,\"lat\":42.9685},\"weather\":[{\"id\":802,\"main\":\"Clouds\",\"description\":\"scattered clouds\",\"icon\":\"03d\"}],\"base\":\"stations\",\"main\":{\"temp\":262.8,\"feels_like\":259.01,\"temp_min\":260.81,\"temp_max\":264.29,\"pressure\":1020,\"humidity\":64},\"visibility\":10000,\"wind\":{\"speed\":1.79,\"deg\":342,\"gust\":4.92},\"clouds\":{\"all\":40},\"dt\":1643479044,\"sys\":{\"type\":2,\"id\":2031741,\"country\":\"US\",\"sunrise\":1643459581,\"sunset\":1643494984},\"timezone\":-18000,\"id\":0,\"name\":\"Buffalo\",\"cod\":200}";

Parse

        binding.button.setOnClickListener(
		...
                        binding.textview.setText( "JSON->" + json + "\n\n" + parseJson(json) );

    private String parseJson(String input) {
        String output = "Error parsing Json";
        try {
            JSONObject jsonRootObject = new JSONObject(input);
            JSONArray jsonWeatherArray = jsonRootObject.getJSONArray("weather");
            String cond = ((JSONObject) jsonWeatherArray.getJSONObject(0)).getString("main");

            JSONObject  jsonMainObject = jsonRootObject.getJSONObject("main");
            double temp = jsonMainObject.getDouble("temp");
            String city = jsonRootObject.optString("name").toString();
            output = city + " :condition is " + cond + ", at " + String.format( "%.2f", (temp-273.15)) + " celsius";

        } catch (JSONException e) {
            e.printStackTrace();
        }
        return output;
    }

External Library in Android

A09-JSON-ver03
Use other's off-the-shelf code in Android
Two ways to use an external library
- 1. gradle "implemetation xxxxx." -> directly from Github etc.,
- 2. gradle "implementation files (xxxxx.jar)" -> copy .jar in the project
Which one is 'better'? -- .jar is MORE RELIABLE
Github library can be hard to predict in future
Add your AAR or JAR as a dependency
- Tutorials here, here
- (1) create folder either right click app->New Directory or directly under app/mylib
- (2) either build.gradle or File->Project Structure->app dependency-> src/mylib/json.jar
- result in implementation files('src/mylib/json.jar')
JSON Simple

Parse

import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;

    private String parseJson(String input) {

        //// HERE
        // JSON Simple
        // https://www.tutorialspoint.com/json_simple/json_simple_quick_guide.htm
        // https://mkyong.com/java/json-simple-example-read-and-write-json/
        // https://mkyong.com/java/json-simple-how-to-parse-json/

        String output = "Error parsing Json";
        JSONParser parser = new JSONParser();
        try {
            JSONObject jsonRootObject = (JSONObject) parser.parse(input);
            JSONArray jsonWeatherArray = (JSONArray) jsonRootObject.get("weather");
            String cond = ((JSONObject) jsonWeatherArray.get(0)).get("main").toString();

            JSONObject jsonMainObject = (JSONObject) jsonRootObject.get("main");
            double temp = Double.parseDouble(jsonMainObject.get("temp").toString());
            String city = jsonRootObject.get("name").toString();
            output = city + " :condition is " + cond + ", at " + String.format("%.2f", (temp - 273.15)) + " celsius";
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return output;
    }

File Reader

A09-JSON-ver04
JSON string is too long and complex, a text-based file could be better
Recall 2 file locatioins
- 1. in the app
- 2. sdcard
Create resource folder res/raw

Copy weather.json to raw

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
	
        binding.button.setOnClickListener(
		...
                       // https://www.tutorialspoint.com/how-to-read-a-simple-text-file-in-android-app
                        InputStream is = getResources().openRawResource(R.raw.weather);
                        BufferedReader reader = new BufferedReader(new InputStreamReader(is));
                        binding.textview.setText( "JSON->\n" + parseJson(reader) );
                        ////binding.textview.setText( "JSON->" + json + "\n\n" + parseJson(json) );
                    }
                });

    private String parseJson(BufferedReader reader) {
        String output = "Error parsing Json";
        JSONParser parser = new JSONParser();
        try {
            ////JSONObject jsonRootObject = (JSONObject) parser.parse(input);
            JSONObject jsonRootObject = (JSONObject) parser.parse(reader);
            JSONArray jsonWeatherArray = (JSONArray) jsonRootObject.get("weather");
            String cond = ((JSONObject) jsonWeatherArray.get(0)).get("main").toString();

            JSONObject  jsonMainObject = (JSONObject) jsonRootObject.get("main");
            double temp = Double.parseDouble(jsonMainObject.get("temp").toString());
            String city = jsonRootObject.get("name").toString();
            output = city + " :condition is " + cond + ", at " + String.format( "%.2f", (temp-273.15)) + " celsius";
        } catch (ParseException e) {
            e.printStackTrace();
        }
        catch (IOException e) {
            e.printStackTrace();
        }
        return output;
    }

Tips of the Day

Planning of Quiz Exercise
Weather API
JSON
External Libaray jar
File Reader