String userChoosenTask;

/**Called when activity is first created.  */
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    Button button = findViewById(R.id.btnSelectPhoto);
    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            selectImage(view);
        }
    });
}


//Method for selecting image from camera or gallery
private void selectImage(View view){
    final CharSequence[] items = {"Take Photo", "Choose from Library","Cancel"};
    AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
    builder.setTitle("Add Photo!");
    builder.setItems(items, new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialogInterface, int i) {
            boolean result = Utility.checkPermission(MainActivity.this);
            if (items[i].equals("Take Photo")) {
                userChoosenTask = "Take Photo";
                if (result) {
                    cameraIntent();
                }
            }
            else if (items[i].equals("Choose from library")){
                userChoosenTask = "Choose from library";
                if(result)
                    galleryIntent();
            }
            else if(items[i].equals("Cancel")){
                dialogInterface.dismiss();
            }
        }
    });
    builder.show();
    }

//Gallery Intent Method
public static final int SELECT_FILE =2;
private void galleryIntent()
{
    Intent intent = new Intent();
    intent.setType("image/*");
    intent.setAction(Intent.ACTION_GET_CONTENT);
    startActivityForResult(Intent.createChooser(intent, "Select File"), SELECT_FILE);
}


// Camera Intent Method
public static final int REQUEST_IMAGE_CAPTURE =1;
private void cameraIntent()
{
    Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
    startActivityForResult(intent, REQUEST_IMAGE_CAPTURE);
}

//Requesting Permission at run time
public class Utility {
    public static final int MY_PERMISSIONS_REQUEST_READ_EXTERNAL_STORAGE = 123;

    public static boolean checkPermission(final Context context) {

        int currentAPIVersion = Build.VERSION.SDK_INT;
        if (currentAPIVersion >= Build.VERSION_CODES.M) {
            if (ContextCompat.checkSelfPermission(context, Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
                if (ActivityCompat.shouldShowRequestPermissionRationale((Activity) context, Manifest.permission.READ_EXTERNAL_STORAGE)) {
                    AlertDialog.Builder alertBuilder = new AlertDialog.Builder(context);
                    alertBuilder.setCancelable(true);
                    alertBuilder.setTitle("Permission necessary");
                    alertBuilder.setMessage("External storage permission is necessary");
                    alertBuilder.setPositiveButton(android.R.string.yes, new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialogInterface, int i) {
                            ActivityCompat.requestPermissions((Activity) context, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, MY_PERMISSIONS_REQUEST_READ_EXTERNAL_STORAGE);
                        }
                    });
                    AlertDialog alert = alertBuilder.create();
                    alert.show();
                } else {
                    ActivityCompat.requestPermissions((Activity) context, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, MY_PERMISSIONS_REQUEST_READ_EXTERNAL_STORAGE);
                }
                return false;
            } else {
                return true;
            }
        } else {
            return true;
        }
    }

//Gallery Intent Method
public static final int SELECT_FILE =2;
private void galleryIntent()
{
    Intent intent = new Intent();
    intent.setType("image/*");
    intent.setAction(Intent.ACTION_GET_CONTENT);
    startActivityForResult(Intent.createChooser(intent, "Select File"), SELECT_FILE);
}

}
            break;
    }