Android for [smart] dummies (complete project here: https://gitlab.com/panchicore/android-introduction)

Android Introduction

10. blank activity
20. hello world
    change hello world
    saludations
30. menu
  create menu layout
  override onCreateOptionsMenu y onOptionsItemSelected
40. open activity con Intent
50. application class
60. models
70. create the API (https://sheetsu.com/)
80. call the API with Volley (gradle ... https://github.com/mcxiaoke/android-volley)
    ¿porque volley? http://developer.android.com/training/volley/index.html
    ¿porque async? http://developer.android.com/reference/android/os/NetworkOnMainThreadException.html
81. android permissions (INTERNET permission) <uses-permission android:name="android.permission.INTERNET"/>
82. mapping to models
90. layouts (lists and list items)
100. list view adapters and bindings
110. set event listerns on list views (OnItemClickListener, OnItemLongClickListener)
120. passing data to intents
130. refactor
140. delete from API and Adapter
    
    


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challenges here:

1000. morbo lifecycle (http://i.stack.imgur.com/2CP6n.png)

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challenges home:
2000. move delete to detail view
2010. add activity (POST)
2020. edit activity (PUT)
2010. passing mapped object to intents with Parcelable, not just strings

MainActivity.java

package com.panchicore.morosos;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.ProgressBar;
import android.widget.Toast;

import com.android.volley.Request;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonArrayRequest;
import com.android.volley.toolbox.StringRequest;
import com.panchicore.morosos.adapter.DebtorsListAdapter;
import com.panchicore.morosos.model.Debtor;

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

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

    private ListView mDebtorsListView;
    private ArrayList<Debtor> mDebtorsList;
    private DebtorsListAdapter mDebtorsListAdapter;
    private ProgressBar loadingProgressBar;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // prepare objects
        mDebtorsList = new ArrayList<>();
        mDebtorsListAdapter = new DebtorsListAdapter(getApplicationContext(), R.id.debtorsListView, mDebtorsList);

        // prepare UI
        mDebtorsListView = (ListView) findViewById(R.id.debtorsListView);
        loadingProgressBar = (ProgressBar) findViewById(R.id.loadingProgressBar);
        mDebtorsListView.setAdapter(mDebtorsListAdapter);

        // do API calls
        requestAllDebtors();

        // prepare listeners
        mDebtorsListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                Debtor d = mDebtorsList.get(position);
                Intent i = new Intent(getApplicationContext(), DebtorActivity.class);
                i.putExtra("NAME", d.getName());
                startActivity(i);
            }
        });

        mDebtorsListView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
            @Override
            public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
                Debtor d = mDebtorsList.get(position);
                mDebtorsList.remove(position);
                mDebtorsListAdapter.remove(d);

                deleteDebtor(d);
                return true;
            }
        });



    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.menu, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if(item.getItemId() == R.id.action_item_add){
            Intent i = new Intent(getApplicationContext(), AddActivity.class);
            i.putExtra("NAME", "LUIS PALLARES");
            startActivity(i);
        }

        if(item.getItemId() == R.id.action_item_refresh){
            requestAllDebtors();
        }
        return super.onOptionsItemSelected(item);
    }

    public void requestAllDebtors(){

        mDebtorsList.clear();
        mDebtorsListAdapter.clear();
        loadingProgressBar.setVisibility(View.VISIBLE);

        final String URL = "https://sheetsu.com/apis/v1.0/00151fd1";
        JsonArrayRequest request = new JsonArrayRequest(URL, new Response.Listener<JSONArray>() {
            @Override
            public void onResponse(JSONArray response) {
                Log.i("RESULT", response.toString());
                for(int i = 0; i < response.length(); i++){
                    try {
                        JSONObject o = (JSONObject) response.get(i);
                        if(!o.getString("id").isEmpty()){
                            Debtor d = new Debtor(o);
                            mDebtorsList.add(d);
                        }
                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
                mDebtorsListAdapter.notifyDataSetChanged();
                loadingProgressBar.setVisibility(View.GONE);
            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                Log.e("ERROR", error.getMessage());
            }
        });
        Application.getApplication().addToRequestQueue(request);
    }


    public void deleteDebtor(Debtor d){
        Toast.makeText(getApplicationContext(), "Borrando...", Toast.LENGTH_SHORT).show();
        final String URL = "https://sheetsu.com/apis/v1.0/00151fd1/id/" + d.getId();
        StringRequest request = new StringRequest(Request.Method.DELETE, URL, new Response.Listener<String>() {
            @Override
            public void onResponse(String response) {
                Toast.makeText(getApplicationContext(), "Borrado OK", Toast.LENGTH_SHORT).show();
            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {

            }
        });
        Application.getApplication().addToRequestQueue(request);
    }

}

x100_adapter.java

public class DebtorsListAdapter extends ArrayAdapter<Debtor> {

    private Context context;

    public DebtorsListAdapter(Context context, int resource, List<Debtor> objects) {
        super(context, resource, objects);
        this.context = context;
    }

    private class ViewHolder{
        TextView name;
        TextView amount;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        ViewHolder holder = null;
        Debtor d = getItem(position);

        LayoutInflater mInflater = (LayoutInflater) context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);

        if(convertView == null){
            convertView = mInflater.inflate(R.layout.debtor_listitem_row, null);
            holder = new ViewHolder();
            holder.name = (TextView) convertView.findViewById(R.id.nameTextView);
            holder.amount = (TextView) convertView.findViewById(R.id.amountTextView);
            convertView.setTag(holder);
        }else{
            holder = (ViewHolder) convertView.getTag();
        }
        
        holder.name.setText(d.getName());
        holder.amount.setText(d.getAmount().toString());
        
        return convertView;
    }
}

x120_data_to_intents.java

mDebtorsListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                Debtor d = mDebtorsList.get(position);
                Log.d("CLICKED", d.getName());
                Intent i = new Intent(getApplicationContext(), DebtorDetailActivity.class);
                i.putExtra("NAME", d.getName());
                i.putExtra("AMOUNT", d.getAmount());
                startActivity(i);
            }
        });

X140_deleting.java

public void delete(Debtor debtor){
        String URL = "https://sheetsu.com/apis/v1.0/fddc517a/id/" + debtor.getId();
        Toast.makeText(getApplicationContext(), "Deleting " + debtor.getName(), Toast.LENGTH_SHORT).show();
        StringRequest request = new StringRequest(Request.Method.DELETE, URL, new Response.Listener<String>() {
            @Override
            public void onResponse(String response) {
                Log.d("DELETE", response);
                Toast.makeText(getApplicationContext(), "DONE", Toast.LENGTH_SHORT).show();
                listAllDebtors(); // reloader
            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                Log.d("DELETE", error.toString());
            }
        });
        Application.getApplication().addToRequestQueue(request);
    }

x30_menu.java

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    tools:context="com.panchicore.tester.MainActivity">

    <item android:id="@+id/action_item"
        android:title="@string/menu_item"
        android:orderInCategory="1"
        app:showAsAction="always"/>

</menu>

x50_app.java

public class Application extends android.app.Application {

    private static Application sInstance;

    @Override
    public void onCreate() {
        sInstance = this;
        Log.d("APP", "Iniciando App");
        super.onCreate();
    }

    public static Application getApplication() {
        return sInstance;
    }

    public void sayHello(){
        Log.d("APP", "Hola!!");
    }
}

x80_volley_ap.java

    private RequestQueue mRequestQueue;
    
    /**
     * @return The Volley Request queue, the queue will be created if it is null
     */
    public RequestQueue getRequestQueue() {
        // lazy initialize the request queue, the queue instance will be
        // created when it is accessed for the first time
        if (mRequestQueue == null) {
            mRequestQueue = Volley.newRequestQueue(getApplicationContext());
        }

        return mRequestQueue;
    }

    /**
     * Adds the specified request to the global queue, if tag is specified
     * then it is used else Default TAG is used.
     */
    public <T> void addToRequestQueue(Request<T> req, String tag) {
        // set the default tag if tag is empty
        req.setTag(TextUtils.isEmpty(tag) ? "Volley" : tag);

        VolleyLog.d("Adding request to queue: %s", req.getUrl());

        getRequestQueue().add(req);
    }

    /**
     * Adds the specified request to the global queue using the Default TAG.
     */
    public <T> void addToRequestQueue(Request<T> req) {
        // set the default tag if tag is empty
        req.setTag("Volley");

        getRequestQueue().add(req);
    }

    /**
     * Cancels all pending requests by the specified TAG, it is important
     * to specify a TAG so that the pending/ongoing requests can be cancelled.
     */
    public void cancelPendingRequests(Object tag) {
        if (mRequestQueue != null) {
            mRequestQueue.cancelAll(tag);
        }
    }

x81_volley_requests.java

// GET

final String URL = "/volley/resource/12";
// pass second argument as "null" for GET requests
JsonObjectRequest req = new JsonObjectRequest(URL, null,
       new Response.Listener<JSONObject>() {
           @Override
           public void onResponse(JSONObject response) {
               try {
                   VolleyLog.v("Response:%n %s", response.toString(4));
               } catch (JSONException e) {
                   e.printStackTrace();
               }
           }
       }, new Response.ErrorListener() {
           @Override
           public void onErrorResponse(VolleyError error) {
               VolleyLog.e("Error: ", error.getMessage());
           }
       });
       
       
// POST

final String URL = "/volley/resource/12";
// Post params to be sent to the server
HashMap<String, String> params = new HashMap<String, String>();
params.put("token", "AbCdEfGh123456");

JsonObjectRequest req = new JsonObjectRequest(URL, new JSONObject(params),
       new Response.Listener<JSONObject>() {
           @Override
           public void onResponse(JSONObject response) {
               try {
                   VolleyLog.v("Response:%n %s", response.toString(4));
               } catch (JSONException e) {
                   e.printStackTrace();
               }
           }
       }, new Response.ErrorListener() {
           @Override
           public void onErrorResponse(VolleyError error) {
               VolleyLog.e("Error: ", error.getMessage());
           }
       });
       
// GET LIST
final String URL = "/volley/resource/all?count=20";
JsonArrayRequest req = new JsonArrayRequest(URL, new Response.Listener<JSONArray> () {
    @Override
    public void onResponse(JSONArray response) {
        try {
            VolleyLog.v("Response:%n %s", response.toString(4));
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }
}, new Response.ErrorListener() {
    @Override
    public void onErrorResponse(VolleyError error) {
        VolleyLog.e("Error: ", error.getMessage());
    }
});
       
       
// add the request object to the queue to be executed
Application.getInstance().addToRequestQueue(req);



// SEND HEADERS
JsonObjectRequest req = new JsonObjectRequest(URL, new JSONObject(params),
           new Response.Listener<JSONObject>() {
               @Override
               public void onResponse(JSONObject response) {
                   // handle response
               }
           }, new Response.ErrorListener() {
               @Override
               public void onErrorResponse(VolleyError error) {
                   // handle error                        
               }
           }) {

       @Override
       public Map<String, String> getHeaders() throws AuthFailureError {
           HashMap<String, String> headers = new HashMap<String, String>();
           headers.put("CUSTOM_HEADER", "Yahoo");
           headers.put("ANOTHER_CUSTOM_HEADER", "Google");
           return headers;
       }
   };

x82_mapping.java

// MODEL

 public Debtor(JSONObject response) throws JSONException {
        setId(response.getString("id"));
        setName(response.getString("name"));
        setAmount(Integer.parseInt(response.getString("amount")));
        setSendMoto(response.getBoolean("sendMoto"));
    }

// REQUEST

mDebtorsList = new ArrayList<>();

        String URL = "https://sheetsu.com/apis/v1.0/fddc517a";
        JsonArrayRequest request = new JsonArrayRequest(URL, new Response.Listener<JSONArray>() {
            @Override
            public void onResponse(JSONArray response) {
                Log.d("REQ", response.toString());

                for(int i = 0; i<response.length(); i++){
                    try {
                        JSONObject o = (JSONObject) response.get(i);
                        Debtor d = new Debtor(o);
                        Log.d("DEBT", d.getName());
                        Log.d("DEBT", "" + d.isSendMoto());

                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                Log.e("REQ", error.toString());
            }
        });

        Application.getApplication().addToRequestQueue(request);

        <meta-data
            android:name="android.support.PARENT_ACTIVITY"
            android:value=".MainActivity" />