Android build apk file with command line

Google Play

build apk
- gradlew assembleDebug
build apk when running device
    for debug
    - gradlew installDebug
    for release
    - gradlew installRelease


buildTypes {
        release {
            minifyEnabled false
            signingConfig signingConfigs.release
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
            buildConfigField "boolean", "ENABLE_DEBUG", "false"
        }
        debug {
            buildConfigField "boolean", "ENABLE_DEBUG", "true"
        }
    }

[Android] Retrofit library

compile 'com.google.code.gson:gson:2.6.2'
compile 'com.squareup.retrofit2:retrofit:2.0.2'
compile 'com.squareup.retrofit2:converter-gson:2.0.2'



public class ApiClient {
    public static final String BASE_URL = "your URL";
    private static Retrofit retrofit = null;

    public static Retrofit getClient() {
        if (retrofit == null) {
            retrofit = new Retrofit.Builder()
                    .baseUrl(BASE_URL)
                    .addConverterFactory(GsonConverterFactory.create())
                    .build();
        }
        return retrofit;
    }
}

public interface ApiInterface {
    @GET("Retrofit.php")
    Call<List<Message>> getInbox();
}

public class Message {
    public int id;
    public String msg;
    public String url;

    public Message(int id, String msg, String url) {
        this.id = id;
        this.msg = msg;
        this.url = url;
    }
}

public class MainActivity extends AppCompatActivity {
    String TAG = "MainActivity";
    @Override    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ApiInterface apiService = ApiClient.getClient().create(ApiInterface.class);
        Call<List<Message>> call = apiService.getInbox();
        call.enqueue(new Callback<List<Message>>() {
            @Override
            public void onResponse(Call<List<Message>> call, Response<List<Message>> response) {
                // TODO - avoid looping
                List<Message> messageList = response.body();
                for (Message message : messageList) {
                    Log.d(TAG, new Gson().toJson(message));
                }
            }
            @Override
            public void onFailure(Call<List<Message>> call, Throwable t) {
                Toast.makeText(getApplicationContext(), "Unable to fetch json: " + t.getMessage(), Toast.LENGTH_LONG).show();
            }
        });
    }
}

    }
}

[Android application] Object with Kotlin android

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main) 

 var user = User("Kotlin", "Kotlin@yahoo.com") 

 var msg: String = "name:" + user.name + "\n" + user.email 

 var tv = findViewById(R.id.tv) as TextView 

 tv.text = msg

    }

    inner class User(var name: String, var email: String)
}

[Android application] Compare code between Kotlin and Java

class MainActivity : AppCompatActivity() {
    // kotlin code 

 var a: Int = 10 

 var b: Int = 5 

 override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main) 

 var btn_hello = findViewById(R.id.btn_hello) as Button 

 var c = a + b 

 var msg: String = "Kotlin" 

 btn_hello.setOnClickListener { 

 view -> 

 Toast.makeText(applicationContext, msg, Toast.LENGTH_SHORT).show() 

        } 

    }
}

[Android] Install Kotlin language for Android Studio

class MainActivity : AppCompatActivity() {
 private var TAG: String = "MainActivity" 

 private var a: Int = 0 

 private var b: Int = 0
 

 override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState) 

 a = 10 

 b = 25 

 Log.d(TAG, "result:" + (a + b)) 

 // result:35 

  }
}

Bottom Sheet

build.gragle file 

compile 'com.android.support:appcompat-v7:25.2.0' 

compile 'com.android.support:design:25.2.0'

MainActivity

public class MainActivity extends AppCompatActivity {
    String TAG = "MainActivity";
    @Override 

 protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState); 

 setContentView(R.layout.activity_main); 

 View bottomSheet = findViewById(R.id.design_bottom_sheet); 

 final BottomSheetBehavior behavior = BottomSheetBehavior.from(bottomSheet); 

 // listen view change 

 behavior.setBottomSheetCallback(new BottomSheetBehavior.BottomSheetCallback() {
            @Override 

 public void onStateChanged(@NonNull View bottomSheet, int newState) {
 switch (newState) {
 case BottomSheetBehavior.STATE_DRAGGING:
 Log.d(TAG, "BottomSheetBehavior.STATE_DRAGGING"); 

 break; 

 case BottomSheetBehavior.STATE_SETTLING:

 Log.d(TAG, "BottomSheetBehavior.STATE_SETTLING"); 

 break; 

 case BottomSheetBehavior.STATE_EXPANDED:

 Log.d(TAG, "BottomSheetBehavior.STATE_EXPANDED"); 

 break; 

 case BottomSheetBehavior.STATE_COLLAPSED:

 Log.d(TAG, "BottomSheetBehavior.STATE_COLLAPSED"); 

 break; 

 case BottomSheetBehavior.STATE_HIDDEN:

 Log.d(TAG, "BottomSheetBehavior.STATE_HIDDEN"); 

 break;                }
            }

            @Override 

 public void onSlide(@NonNull View bottomSheet, float slideOffset) {
                Log.d(TAG, "slideOffset: " + slideOffset); 

                     }
        });
        Button button = (Button) findViewById(R.id.button); 

 button.setOnClickListener(new View.OnClickListener() {
            @Override 

 public void onClick(View view) {
                if (behavior.getState() == BottomSheetBehavior.STATE_COLLAPSED) {
                    behavior.setState(BottomSheetBehavior.STATE_EXPANDED); 

                 } else {
                    behavior.setState(BottomSheetBehavior.STATE_COLLAPSED); 

                 }
                      }
             }); 

          }
}

 activity_main

<?xml version="1.0" encoding="utf-8"?> 

<android.support.design.widget.CoordinatorLayout 

 xmlns:android="http://schemas.android.com/apk/res/android" 

 xmlns:app="http://schemas.android.com/apk/res-auto" 

 xmlns:tools="http://schemas.android.com/tools" 

 android:layout_width="match_parent" 

 android:layout_height="match_parent">
    <android.support.v4.widget.NestedScrollView 

 android:layout_width="match_parent" 

 android:layout_height="match_parent" 

 app:layout_behavior="@string/appbar_scrolling_view_behavior">
        <RelativeLayout 

 android:layout_width="match_parent" 

 android:layout_height="match_parent" 

 android:paddingBottom="@dimen/activity_vertical_margin" 

 android:paddingLeft="@dimen/activity_horizontal_margin" 

 android:paddingRight="@dimen/activity_horizontal_margin" 

 android:paddingTop="@dimen/activity_vertical_margin">
            <ImageView 

 android:id="@+id/image" 

 android:layout_width="wrap_content" 

 android:layout_height="wrap_content" 

 android:layout_centerHorizontal="true" 

 android:src="@mipmap/ic_launcher"/>
            <Button 

 android:id="@+id/button" 

 android:layout_width="wrap_content" 

 android:layout_height="wrap_content" 

 android:layout_below="@+id/image" 

 android:layout_centerHorizontal="true" 

 android:text="Show Bottom Sheet"/> 

 </RelativeLayout> 

 </android.support.v4.widget.NestedScrollView>
    <RelativeLayout 

 android:id="@+id/design_bottom_sheet" 

 android:layout_width="match_parent" 

 android:layout_height="match_parent" 

 android:background="@color/colorAccent" 

 android:paddingBottom="@dimen/activity_vertical_margin" 

 android:paddingLeft="@dimen/activity_horizontal_margin" 

 android:paddingRight="@dimen/activity_horizontal_margin" 

 android:paddingTop="@dimen/activity_vertical_margin" 

 app:behavior_hideable="true" 

 app:behavior_peekHeight="50dp" 

 app:elevation="4dp" 

 app:layout_behavior="@string/bottom_sheet_behavior">
        <TextView 

 android:id="@+id/bottomsheet_text" 

 android:layout_width="wrap_content" 

 android:layout_height="match_parent" 

 android:text="Introducing Bottom Sheets" 

 android:textColor="#FFFFFF"/>
    </RelativeLayout>

</android.support.design.widget.CoordinatorLayout>

FragmentStatePagerAdapter

activity_main 

<LinearLayout

 xmlns:android="http://schemas.android.com/apk/res/android" 

 android:layout_width="match_parent" 

 android:layout_height="match_parent" 

 android:gravity="center_horizontal" 

 android:orientation="vertical" 

 android:padding="4dip">

    <android.support.v4.view.ViewPager 

 android:id="@+id/pager" 

 android:layout_width="match_parent" 

 android:layout_height="0px" 

 android:layout_weight="1">

</android.support.v4.view.ViewPager>

    <LinearLayout 

 android:layout_width="match_parent" 

 android:layout_height="wrap_content" 

 android:layout_weight="0" 

 android:gravity="center" 

 android:measureWithLargestChild="true" 

 android:orientation="horizontal">

        <Button 

 android:id="@+id/goto_first" 

 android:layout_width="wrap_content" 

 android:layout_height="wrap_content" 

 android:text="first">

</Button>

        <Button 

 android:id="@+id/goto_last" 

 android:layout_width="wrap_content" 

 android:layout_height="wrap_content" 

 android:text="last"></Button>
    </LinearLayout>
</LinearLayout>

fragment_image

<?xml version="1.0" encoding="utf-8"?>

 <RelativeLayout 

 xmlns:android="http://schemas.android.com/apk/res/android" 

 android:layout_width="match_parent" 

 android:layout_height="match_parent" >

    <TextView 

 android:id="@+id/text" 

 android:layout_width="match_parent" 

 android:layout_height="wrap_content" 

 android:gravity="center_vertical|center_horizontal" 

 android:text="hello_world" 

 android:textAppearance="?android:attr/textAppearanceMedium" />

    <ImageView 

 android:id="@+id/imageView1" 

 android:layout_width="wrap_content" 

 android:layout_height="wrap_content" 

 android:layout_below="@+id/text" 

 android:layout_centerHorizontal="true" 

 android:layout_marginTop="36dp" 

 android:src="@mipmap/ic_launcher" />

</RelativeLayout>

fragment_pager_list

<?xml version="1.0" encoding="utf-8"?>

 <LinearLayout

 xmlns:android="http://schemas.android.com/apk/res/android" 

 android:layout_width="match_parent" 

 android:layout_height="match_parent" 

 android:background="@android:drawable/gallery_thumb" 

 android:orientation="vertical" >

    <TextView 

 android:id="@+id/text" 

 android:layout_width="match_parent" 

 android:layout_height="wrap_content" 

 android:gravity="center_vertical|center_horizontal" 

 android:text="hello_world" 

 android:textAppearance="?android:attr/textAppearanceMedium" />

    <FrameLayout 

 android:layout_width="match_parent" 

 android:layout_height="0dip" 

 android:layout_weight="1" >

        <ListView 

 android:id="@android:id/list" 

 android:layout_width="match_parent" 

 android:layout_height="match_parent" 

 android:drawSelectorOnTop="false" />
    </FrameLayout>

</LinearLayout>

public class MainActivity extends FragmentActivity {
    static final int ITEMS = 5;
    MyAdapter mAdapter;
    ViewPager mPager;

    @Override 

 protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.fragment_pager);
        mAdapter = new MyAdapter(getSupportFragmentManager());
        mPager = (ViewPager) findViewById(R.id.pager);
        mPager.setAdapter(mAdapter);

        Button button = (Button) findViewById(R.id.first);
        button.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                mPager.setCurrentItem(0);
            }
        });
        button = (Button) findViewById(R.id.last);
        button.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                mPager.setCurrentItem(ITEMS - 1);
            }
        });
    }

    public static class MyAdapter extends FragmentStatePagerAdapter {
        public MyAdapter(FragmentManager fragmentManager) {
            super(fragmentManager);
        }

        @Override 

 public int getCount() {
            return ITEMS;
        }

        @Override 

 public Fragment getItem(int position) {
            switch (position) {
                case 0: // Fragment # 0 - This will show image 

 return ImageFragment.init(position);
                case 1: // Fragment # 1 - This will show image 

 return ImageFragment.init(position);
                default:// Fragment # 2-9 - Will show list 

 return ArrayListFragment.init(position);
            }
        }
    }


}

public class ImageFragment extends Fragment {
    int fragVal;

    static ImageFragment init(int val) {
        ImageFragment truitonFrag = new ImageFragment();
        // Supply val input as an argument. 

 Bundle args = new Bundle();
        args.putInt("val", val);
        truitonFrag.setArguments(args);
        return truitonFrag;
    }

    @Override 

 public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        fragVal = getArguments() != null ? getArguments().getInt("val") : 1;
    }

    @Override 

 public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View layoutView = inflater.inflate(R.layout.fragment_image, container,
                false);
        View tv = layoutView.findViewById(R.id.text);
        ((TextView) tv).setText("Truiton Fragment #" + fragVal);
        return layoutView;
    }
}

public class ArrayListFragment extends ListFragment {
    int fragNum;
    String arr[] = {"1", "2", "2", "3", "4", "5"};

    static ArrayListFragment init(int val) {
        ArrayListFragment truitonList = new ArrayListFragment();

        // Supply val input as an argument. 

 Bundle args = new Bundle();
        args.putInt("val", val);
        truitonList.setArguments(args);

        return truitonList;
    }

    /**     * Retrieving this instance's number from its arguments.     */ 

 @Override 

 public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        fragNum = getArguments() != null ? getArguments().getInt("val") : 1;
    }

    /**     * The Fragment's UI is a simple text view showing its instance number and 

 * an associated list.     */ 

 @Override 

 public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View layoutView = inflater.inflate(R.layout.fragment_pager_list,
                container, false);
        View tv = layoutView.findViewById(R.id.text);
        ((TextView) tv).setText("Truiton Fragment #" + fragNum);
        return layoutView;
    }

    @Override 

 public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        setListAdapter(new ArrayAdapter<String>(getActivity(),
                android.R.layout.simple_list_item_1, arr));
    }

    @Override 

 public void onListItemClick(ListView l, View v, int position, long id) {
        Log.i("Truiton FragmentList", "Item clicked: " + id);
    }
} 

Multi Screen in Android 7 Example Code

Fragment in Android

public class MainActivity extends AppCompatActivity {
    String TAG = "MainActivity";

    @Override 

 protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Log.v(TAG, "<<screen>>");


        FragmentTransaction transaction = getFragmentManager().beginTransaction();
        FragmentMain fragmentMain = new FragmentMain();
        transaction.addToBackStack("fragmentMain");
        transaction.replace(R.id.container, fragmentMain);
        transaction.commit();

    }


    public boolean handleBackStack() {
        int count = getFragmentManager().getBackStackEntryCount();
        Log.v(TAG, String.valueOf(count));
        if (count == 1) {
            finish();
        } else {
            FragmentTransaction transaction = getFragmentManager().beginTransaction();
            getFragmentManager().popBackStackImmediate();
            transaction.commit();
        }
        return true;
    }


    //handle the hardware back press 

 @Override 

 public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK) {
            handleBackStack();
            return true;
        }
        return super.onKeyDown(keyCode, event);
    }
}

public class FragmentMain extends Fragment {


    public FragmentMain() {
        // Required empty public constructor    }

    @Override 

 public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        View view = inflater.inflate(R.layout.fragment_main, container, false);
        final Button mButtonFragmentMain=(Button)view.findViewById(R.id.button__fragment_main);

        Log.v("<< main fragment>>","<<screen>>");

        mButtonFragmentMain.setOnClickListener(new View.OnClickListener() {
            @Override 

 public void onClick(View view) {
                FragmentTransaction transaction = getFragmentManager().beginTransaction();
                FragmentChild fragmentChild = new FragmentChild();
                transaction.addToBackStack("fragmentChild");
                transaction.replace(R.id.container, fragmentChild);
                transaction.commit();

            }
        });


        return view;
    }
}

public class FragmentChild extends Fragment {


    public FragmentChild() {
        // Required empty public constructor    }


    @Override 

 public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        View view = inflater.inflate(R.layout.fragment_child, container, false);



        return view;
    }
}

activity_main

<?xml version="1.0" encoding="utf-8"?> 

<FrameLayout 

 xmlns:android="http://schemas.android.com/apk/res/android" 

 android:id="@+id/container" 

 android:layout_width="match_parent" 

 android:layout_height="match_parent" 

 android:orientation="vertical">

</FrameLayout>
 

fragment_main

<RelativeLayout 

 xmlns:android="http://schemas.android.com/apk/res/android" 

 android:layout_width="match_parent" 

 android:layout_height="match_parent" 

 android:paddingBottom="@dimen/activity_vertical_margin" 

 android:paddingLeft="@dimen/activity_horizontal_margin" 

 android:paddingRight="@dimen/activity_horizontal_margin" 

 android:paddingTop="@dimen/activity_vertical_margin">

    <TextView 

 android:layout_width="wrap_content" 

 android:layout_height="wrap_content" 

 android:layout_centerHorizontal="true" 

 android:layout_marginTop="20dp" 

 android:text="Main Fragment Screen" 

 android:textSize="26sp" 

 android:textStyle="bold" />

    <Button 

 android:id="@+id/button__fragment_main" 

 android:layout_width="match_parent" 

 android:layout_height="wrap_content" 

 android:layout_centerInParent="true" 

 android:paddingBottom="15dp" 

 android:paddingTop="15dp" 

 android:text="Open Child Fragment" 

 android:textSize="20sp" />
</RelativeLayout>
 

fragment_child

<RelativeLayout  

xmlns:android="http://schemas.android.com/apk/res/android" 

 android:layout_width="match_parent" 

 android:layout_height="match_parent" 

 android:paddingBottom="@dimen/activity_vertical_margin" 

 android:paddingLeft="@dimen/activity_horizontal_margin" 

 android:paddingRight="@dimen/activity_horizontal_margin" 

 android:paddingTop="@dimen/activity_vertical_margin">

    <TextView 

 android:layout_width="wrap_content" 

 android:layout_height="wrap_content" 

 android:layout_centerInParent="true" 

 android:text="Child Fragment Screen" 

 android:textSize="26sp" 

 android:textStyle="bold" />
</RelativeLayout>