tweet posting

Loklak Wok Android is a peer harvester that posts collected tweets to the Loklak Server. Not only it is a peer harvester, but also provides users to post their tweets from the app. Images and location of the user can also be attached in the tweet. This blog explains Adding Dependencies to the project In app/build.gradle: apply plugin: 'com.android.application' apply plugin: 'me.tatarka.retrolambda' android { ... packagingOptions { exclude 'META-INF/rxjava.properties' } } dependencies { ... compile 'com.google.code.gson:gson:2.8.1' compile 'com.squareup.retrofit2:retrofit:2.3.0' compile 'com.squareup.retrofit2:converter-gson:2.3.0' compile 'com.squareup.retrofit2:adapter-rxjava2:2.3.0' compile 'io.reactivex.rxjava2:rxjava:2.0.5' compile 'io.reactivex.rxjava2:rxandroid:2.0.1' }   In build.gradle project level: dependencies { classpath 'com.android.tools.build:gradle:2.3.3' classpath 'me.tatarka:gradle-retrolambda:3.2.0' }   Implementation User first authorize the application, so that they are able to post tweet from the app. For posting tweet statuses/update API endpoint of twitter is used and for attaching images with tweet media/upload API endpoint is used. As, photos and location can be attached in a tweet, for Android Marshmallow and above we need to ask runtime permissions for camera, gallery and location. The related permissions are mentioned in Manifest file first <uses-permission android:name="android.permission.CAMERA" /> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" /> <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" /> // for location <uses-feature android:name="android.hardware.location.gps"/> <uses-feature android:name="android.hardware.location.network"/>   If, the device is using an OS below Android Marshmallow, there will be no runtime permissions, the user will be asked permissions at the time of installing the app. Now, runtime permissions are asked, if the user had already granted the permission the related activity (camera, gallery or location) is started. For camera permissions, onClickCameraButton is called @OnClick(R.id.camera) public void onClickCameraButton() { int permission = ContextCompat.checkSelfPermission( getActivity(), Manifest.permission.CAMERA); if (isAndroidMarshmallowAndAbove && permission != PackageManager.PERMISSION_GRANTED) { String[] permissions = { Manifest.permission.CAMERA, Manifest.permission.WRITE_EXTERNAL_STORAGE, Manifest.permission.READ_EXTERNAL_STORAGE }; requestPermissions(permissions, CAMERA_PERMISSION); } else { startCameraActivity(); } }   To start the camera activity if the permission is already granted, startCameraActivity method is called private void startCameraActivity() { Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE); File dir = getActivity().getExternalFilesDir(Environment.DIRECTORY_PICTURES); mCapturedPhotoFile = new File(dir, createFileName()); Uri capturedPhotoUri = getImageFileUri(mCapturedPhotoFile); intent.putExtra(MediaStore.EXTRA_OUTPUT, capturedPhotoUri); startActivityForResult(intent, REQUEST_CAPTURE_PHOTO); }   If the user decides to save the photo clicked from camera activity, the photo should be saved by creating a file and its uri is required to display the saved photo. The filename is created using createFileName method private String createFileName() { String timeStamp = new SimpleDateFormat("ddMMyyyy_HHmmss").format(new Date()); return "JPEG_" + timeStamp + ".jpg"; }   and uri is obtained using getImageFileUri private Uri getImageFileUri(File file) { if (Build.VERSION.SDK_INT < Build.VERSION_CODES.N) { return Uri.fromFile(file); } else { return FileProvider.getUriForFile(getActivity(), "org.loklak.android.provider", file); } }   Similarly, for the gallery, onClickGalleryButton method is implemented to ask runtime permissions and launch gallery activity if the permission is already granted. @OnClick(R.id.gallery) public void onClickGalleryButton() { int permission = ContextCompat.checkSelfPermission( getActivity(), Manifest.permission.WRITE_EXTERNAL_STORAGE); if (isAndroidMarshmallowAndAbove && permission != PackageManager.PERMISSION_GRANTED) { String[] permissions = { Manifest.permission.WRITE_EXTERNAL_STORAGE, Manifest.permission.READ_EXTERNAL_STORAGE }; requestPermissions(permissions, GALLERY_PERMISSION); } else { startGalleryActivity(); } }   For starting the gallery activity, startGalleryActivity is used private void startGalleryActivity() { Intent intent = new Intent(); intent.setType("image/*"); intent.setAction(Intent.ACTION_GET_CONTENT); intent.putExtra(Intent.EXTRA_ALLOW_MULTIPLE, true); startActivityForResult( Intent.createChooser(intent, "Select images"), REQUEST_GALLERY_MEDIA_SELECTION); }   And finally for location onClickAddLocationButton…