How to give permission programatically in android

- To call isStoragePermissionGranted method in OnCreate()

public boolean isStoragePermissionGranted() {

if (Build.VERSION.SDK_INT >= 23) {            
 if(checkSelfPermission(android.Manifest.permission.
WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED{   
    Log.v("PDF", "Permission is granted");      
    return true;            
} else {           
    Log.v("PDF", "Permission is revoked");            
    ActivityCompat.requestPermissions(this, new String[]  {Manifest.permission.WRITE_EXTERNAL_STORAGE},1); 
    return false;            
  }       
} else {
    //permission is automatically granted on sdk<23 upon installation            
    Log.v("PDF", "Permission is granted");     
    return true;      
  }   
}

How to Use Custom Navigation Drawer in Android

First of all, to add DrawerLayout in main.xml file and inside drawer layout to add lable or listview.

//main.xml

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

<android.support.v4.widget.DrawerLayout 

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

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

 android:id="@+id/drawerLayout"     

 android:layout_width="match_parent"     

 android:layout_height="match_parent"     

android:orientation="vertical">

<LinearLayout     

   android:id="@+id/container" 

   android:layout_width="match_parent"     

   android:layout_height="fill_parent" 

   android:orientation="vertical" 

   android:weightSum="1">

    <include layout="@layout/layout_toolbar" />

    <FrameLayout         

     android:id="@+id/content_frame" 

     android:layout_width="match_parent" 

     android:layout_height="fill_parent">

    //Include layout of main screen 

       <include
           android:id="@+id/home" 

           layout="@layout/fragment_home"             

           android:layout_width="fill_parent"             

           android:layout_height="fill_parent" />
    </FrameLayout>
</LinearLayout>

<LinearLayout     

  android:layout_width="120dp"     

  android:layout_height="match_parent" 

  android:layout_gravity="left|start"
  android:orientation="vertical">

 //Add here lable or listview you want 

 
<LinearLayout 

  android:id="@+id/linear_dashboard"     

  android:layout_width="fill_parent"   

  android:layout_height="wrap_content" 

  android:layout_marginBottom="15dp" 

  android:layout_marginTop="20dp" 

  android:orientation="vertical">

    <ImageView 

      android:layout_width="fill_parent" 

      android:layout_height="30dp"         

      android:layout_gravity="center" 

      android:src="@drawable/ic_launcher" />

    <TextView 

      android:id="@+id/text_dashboard" 

      android:layout_width="fill_parent" 

      android:layout_height="wrap_content" 

      android:layout_marginTop="5dp" 

      android:gravity="center" 

      android:text="Dashboard" 

      android:textColor="@color/white" 

      android:textSize="14dp" />
    </LinearLayout>

 </LinearLayout>

</android.support.v4.widget.DrawerLayout>

//layout_toolbar.xml 

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

<android.support.v7.widget.Toolbar  

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

   android:id="@+id/toolbar" 

   android:layout_width="match_parent" 

   android:layout_height="40dp"

   android:background="@color/action_back">

    <LinearLayout 

      android:layout_width="fill_parent"

      android:layout_height="wrap_content">
 

       <TextView         

          android:layout_width="fill_parent"
          android:gravity="center" 

          android:text="App Name"

          android:textColor="@color/white"  

          android:layout_height="wrap_content">

       </TextView>
   </LinearLayout>
</android.support.v7.widget.Toolbar> 

//fragment_home.xml

<?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="@color/white">

    <LinearLayout
        android:layout_width="fill_parent" 

        android:layout_height="fill_parent" 

        android:weightSum="1">

         <TextView 

            android:layout_width="fill_parent"
            android:gravity="center"            

            android:text="App Name"   

            android:textColor="@color/white"

            android:layout_height="wrap_content">

        </TextView> 

    </LinearLayout> 

</LinearLayout>

Now, In java add following code for Navigation Drawer

public class MainActivity extends AppCompatActivity { 

  //First to make variable of Components 

  Toolbar toolbar;

  public static DrawerLayout drawerLayout;
  private ActionBarDrawerToggle drawerToggle;

 @Overrideprotected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    //First to take Reference of Components

    toolbar = (Toolbar) findViewById(R.id.toolbar);
    spinner_menu = (Spinner) findViewById(R.id.spinner_menu);
    drawerLayout = (DrawerLayout) findViewById(R.id.drawerLayout); 

    // To add Following method in your class
    setSupportActionBar(toolbar);
    initDrawerLayout();

 }

 private void initDrawerLayout() {
    drawerToggle = new ActionBarDrawerToggle(this, drawerLayout, toolbar,
            R.string.drawer_open, R.string.drawer_close) {

        @Override 

        public void onDrawerClosed(View drawerView) {
            super.onDrawerClosed(drawerView);
        }

        @Override 

        public void onDrawerOpened(View drawerView) {
            super.onDrawerOpened(drawerView);

        }
    };

    drawerToggle.setDrawerIndicatorEnabled(false);
    Drawable drawable = ResourcesCompat.getDrawable(getResources(), 

     R.drawable.ic_drawer,getTheme());
    drawerToggle.setHomeAsUpIndicator(drawable);
    drawerToggle.setToolbarNavigationClickListener(new View.OnClickListener() {
        @Override        public void onClick(View v) {
            if (drawerLayout.isDrawerVisible(GravityCompat.START)) {
                drawerLayout.closeDrawer(GravityCompat.START);
            } else {
                drawerLayout.openDrawer(GravityCompat.START);
            }
        }
    });
    drawerLayout.setDrawerListener(drawerToggle);
}

@Overrideprotected void onPostCreate(Bundle savedInstanceState) {
    super.onPostCreate(savedInstanceState);
    drawerToggle.syncState();
}

@Overridepublic void onConfigurationChanged(Configuration newConfig) {
    super.onConfigurationChanged(newConfig);
    drawerToggle.onConfigurationChanged(newConfig);
}

} 

How to use Retrofit Api in Android

1) First of all to add this dependencies in your app/build.gradle file 

compile 'com.squareup.retrofit2:retrofit:2.0.2'

compile 'com.squareup.retrofit2:converter-gson:2.0.2' 

compile 'com.squareup.okhttp3:okhttp:3.4.1' 

compile 'com.squareup.okhttp3:logging-interceptor:3.4.1'

2) then make one java class name Apiclient to declare api base link for getting data 

and this link is demo link so paste your link here 

public class ApiClient {
    public static final String BASE_URL = "http://domainname.com/folder";

    private static Retrofit retrofit = null;


    public static Retrofit getClient() {

        HttpLoggingInterceptor interceptor = new HttpLoggingInterceptor();
        interceptor.setLevel(HttpLoggingInterceptor.Level.BODY);
        OkHttpClient client = new OkHttpClient.Builder().addInterceptor(interceptor)

                                                    .build();

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

3) To make one interface to declare the api name and param list and to use this link 

jsonschema2pojo.org for making pojo class of your response  

public interface APIInterface {

    //For Login    @GET("login")
    Call<GetSetMethod> getLoginResponse(@Query("username") String username,  

@Query("password") String password);

} 

4) Use all method and class in your main class where you want to get response for 

display.here is demo class for your reference 

 private void loginProcessWithRetrofit(final String username, String password) {
    // Showing progress dialog    pDialog = new ProgressDialog(LoginActivity.this);
    pDialog.setMessage("Please wait...");
    pDialog.setCancelable(false);
    pDialog.show();

    APIInterface apiService =
            ApiClient.getClient().create(APIInterface.class);

    Call<GetSetMethod> call = apiService.getLoginResponse(username, password);
    call.enqueue(new Callback<GetSetMethod>() {
        @Override        public void onResponse(Call<GetSetMethod> call, 

            Response<GetSetMethod> response) {
            Log.e("List size", ""+response.raw().request().url());
            String str_success = response.body().getSuccess();
            if (pDialog.isShowing()) {
                pDialog.dismiss();
            }
            if (str_success.equals("1")) {
                //Get Login Response 

                ResponseData responseData = response.body().getResponseData();
                String user_id = responseData.getId();
                String auth_key = responseData.getAuthkey();
                String app_type = responseData.getApp();
                        

                Intent intent = new Intent(getApplicationContext(), MainActivity.class);
                startActivity(intent);
                overridePendingTransition(R.anim.open_next,R.anim.close_next);
                finish();
            } else {
                Toast.makeText(getApplicationContext(), 

              "Username or Password does not Matched", Toast.LENGTH_SHORT).show();
            }
        }

        @Override 

            public void onFailure(Call<GetSetMethod> call, Throwable t) {
            // Log error here since request failed 

               if (pDialog.isShowing()) {
                pDialog.dismiss();
            }
            Toast.makeText(getApplicationContext(), "Login Failed", 

          Toast.LENGTH_SHORT).show();
        }
    });
} 

Facebook Login using custom Button 

In this tutorial first of all if you are using eclipse then to download Facebook SDK from this website 

https://developers.facebook.com/docs/android/ and if you are using Android Studio then import dependencies in build.gradle file compile 'com.facebook.android:facebook-android-sdk:4.5.0'

To make the project in the https://developers.facebook.com/ and get the facebook id and add in to the string.xml file.

In XML file to add this code

<LinearLayout

    android:layout_width="fill_parent"

    android:layout_height="wrap_content"

    android:layout_marginLeft="10dp"

    android:layout_marginRight="10dp"


    android:layout_marginTop="50dp"


    android:orientation="horizontal">




    <Button

        android:id="@+id/btn_facebook"

        android:layout_width="fill_parent"

        android:layout_height="wrap_content"

        android:background="@drawable/fb_btn"

        android:text="Facebook"

        android:textAllCaps="false"

        android:textColor="@android:color/white" />

</LinearLayout> 

In java file add this code

public class LoginActivity extends Activity implements View.OnClickListener {


    Intent intent;

    Button btn_facebook;

    private CallbackManager mCallbackManager;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        requestWindowFeature(Window.FEATURE_NO_TITLE);

        setContentView(R.layout.login);


        // Reference of Component

        btn_facebook = (Button) findViewById(R.id.btn_facebook);


        //Click Listener of Components

        btn_facebook.setOnClickListener(this);


        //Facebook login

        List<String> permissions = new ArrayList<String>();

        permissions.add("email");


        FacebookSdk.sdkInitialize(this.getApplicationContext());

        AppEventsLogger.activateApp(this);

        mCallbackManager = CallbackManager.Factory.create();

        LoginManager.getInstance().registerCallback(mCallbackManager,

                new FacebookCallback<LoginResult>() {

                    @Override

                    public void onSuccess(LoginResult loginResult) {

                        Log.d("Success", "Login");




                        GraphRequest request = GraphRequest.newMeRequest(

                               loginResult.getAccessToken(),

                                new GraphRequest.GraphJSONObjectCallback() {

                                    @Override

                                    public void onCompleted(JSONObject object, GraphResponse response

                                        Log.v("LoginActivity", response.toString());

                                        try {


                                            String id = object.getString("id");

                                            String name = object.getString("name");

                                            //String email = object.getString("email");

                                       //     Toast.makeText(getApplicationContext(), "email ="+email, Toast.LENGTH_LONG).show();

                                           Intent intent = new Intent(getApplicationContext(),Registration.class);

                                            intent.putExtra("Fbname",name);

                                            intent.putExtra("Fbid",id);

                                            startActivity(intent);

                                            overridePendingTransition(R.anim.open_next,R.anim.close_next);

                                            finish();

                                        } catch(Exception e){

                                            e.printStackTrace();

                                        }

                                    }

                                });

                        //Toast.makeText(getApplicationContext(),""+response_code,Toast.LENGTH_LONG).show();

                        Bundle parameters = new Bundle();

                        parameters.putString("fields", "id,name,email,gender,birthday");

                        request.setParameters(parameters);

                        request.executeAsync();

                    }

                    @Override

                    public void onCancel() {

               Toast.makeText(LoginActivity.this, "Login Cancel", Toast.LENGTH_LONG).show();

                    }

                    @Override

                    public void onError(FacebookException exception) {

                        Toast.makeText(LoginActivity.this, exception.getMessage(), Toast.LENGTH_LONG).show();

                    }

                });

    }

    @Override

    public void onClick(View view) {


        switch (view.getId()){

            case R.id.btn_facebook:

                loginFacebook();

                break;

        }

    }

    public void loginFacebook(){

        LoginManager.getInstance().logInWithReadPermissions(this, Arrays.asList("public_profile","email","user_birthday","user_friends"));

    }

    @Override

    protected void onActivityResult(int requestCode, int resultCode, Intent data) {

        super.onActivityResult(requestCode, resultCode, data);

        if(mCallbackManager.onActivityResult(requestCode, resultCode, data)) {

            return;

        }

    }

}

In Android Manifest file you have to add the following meta tag 




<activity    android:name="com.facebook.FacebookActivity"    android:label="@string/app_name"/>

<meta-data    android:name="com.facebook.sdk.ApplicationId"    android:value="@string/app_id" />

<meta-data    android:name="com.facebook.sdk.ApplicationName"    android:value="@string/app_name" />
<meta-data    android:name="com.facebook.sdk.WebDialogTheme"    android:resource="@android:style/Theme.Translucent.NoTitleBar" />

<provider    android:name="com.facebook.FacebookContentProvider"    android:authorities="com.facebook.app.FacebookContentProvider233936543368280"    android:exported="true" />