Error non-default constructors in fragments

I am dealing with maps apiv2. And I am getting the following error while coding for Dialog Fragment class.

Error : Avoid non-default constructors in fragments: use a default constructor plus Fragment#setArguments(Bundle) instead:

This is the code :

public PlaceDialogFragment(){
    super();
}

public PlaceDialogFragment(Place place, DisplayMetrics dm){
    super();
    this.mPlace = place;
    this.mMetrics = dm;
}

Any help wud be appreciated..

Revised: This is the whole code...I m kind of a newbie and never before dealt with fragments..I was going through a maps tut and found this..can you elaborate now wat u were trying to explain..

package com.example.travelplanner;

import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v4.app.DialogFragment;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.ViewFlipper;

// Defining DialogFragment class to show the place details with photo
public class PlaceDialogFragment extends DialogFragment{

    TextView mTVPhotosCount = null;
    TextView mTVVicinity = null;
    ViewFlipper mFlipper = null;
    Place mPlace = null;
    DisplayMetrics mMetrics = null;

    public PlaceDialogFragment(){
        super();
    }

    public PlaceDialogFragment(Place place, DisplayMetrics dm){
        super();
        this.mPlace = place;
        this.mMetrics = dm;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {

        // For retaining the fragment on screen rotation
        setRetainInstance(true);
        super.onCreate(savedInstanceState);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                            Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.dialog_layout, null);

        // Getting reference to ViewFlipper
        mFlipper = (ViewFlipper) v.findViewById(R.id.flipper);

        // Getting reference to TextView to display photo count
        mTVPhotosCount = (TextView) v.findViewById(R.id.tv_photos_count);

        // Getting reference to TextView to display place vicinity
        mTVVicinity = (TextView) v.findViewById(R.id.tv_vicinity);

        if(mPlace!=null){

            // Setting the title for the Dialog Fragment
            getDialog().setTitle(mPlace.mPlaceName);

            // Array of references of the photos
            Photo[] photos = mPlace.mPhotos;

            // Setting Photos count
            mTVPhotosCount.setText("Photos available : " + photos.length);

            // Setting the vicinity of the place
            mTVVicinity.setText(mPlace.mVicinity);

            // Creating an array of ImageDownloadTask to download photos
            ImageDownloadTask[] imageDownloadTask = new ImageDownloadTask[photos.length];

            int width = (int)(mMetrics.widthPixels*3)/4;
            int height = (int)(mMetrics.heightPixels*1)/2;

            String url = "https://maps.googleapis.com/maps/api/place/photo?";
            String key = "key=AIzaSyBSo1xlML-tOFTCdJb6qIbVnF9e7y5nj0o";
            String sensor = "sensor=true";
            String maxWidth="maxwidth=" + width;
            String maxHeight = "maxheight=" + height;
            url = url + "&" + key + "&" + sensor + "&" + maxWidth + "&" + maxHeight;

            // Traversing through all the photoreferences
            for(int i=0;i<photos.length;i++){
                // Creating a task to download i-th photo
                imageDownloadTask[i] = new ImageDownloadTask();

                String photoReference = "photoreference="+photos[i].mPhotoReference;

                // URL for downloading the photo from Google Services
                url = url + "&" + photoReference;

                // Downloading i-th photo from the above url
                imageDownloadTask[i].execute(url);
            }
        }
        return v;
    }

    @Override
    public void onDestroyView() {
        if (getDialog() != null && getRetainInstance())
            getDialog().setDismissMessage(null);
            super.onDestroyView();
    }

    private Bitmap downloadImage(String strUrl) throws IOException{
        Bitmap bitmap=null;
        InputStream iStream = null;
        try{
            URL url = new URL(strUrl);

            /** Creating an http connection to communcate with url */
            HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();

            /** Connecting to url */
            urlConnection.connect();

            /** Reading data from url */
            iStream = urlConnection.getInputStream();

            /** Creating a bitmap from the stream returned from the url */
            bitmap = BitmapFactory.decodeStream(iStream);

        }catch(Exception e){
            Log.d("Exception while downloading url", e.toString());
        }finally{
            iStream.close();
        }
        return bitmap;
    }

    private class ImageDownloadTask extends AsyncTask<String, Integer, Bitmap>{
        Bitmap bitmap = null;
        @Override
        protected Bitmap doInBackground(String... url) {
            try{
                // Starting image download
                bitmap = downloadImage(url[0]);
            }catch(Exception e){
                Log.d("Background Task",e.toString());
            }
            return bitmap;
        }

        @Override
        protected void onPostExecute(Bitmap result) {
            // Creating an instance of ImageView to display the downloaded image
            ImageView iView = new ImageView(getActivity().getBaseContext());

            // Setting the downloaded image in ImageView
            iView.setImageBitmap(result);

            // Adding the ImageView to ViewFlipper
            mFlipper.addView(iView);

            // Showing download completion message
            Toast.makeText(getActivity().getBaseContext(), "Image downloaded successfully", Toast.LENGTH_SHORT).show();
        }
    }
}

Answers


if you like to be out of rules just do next

@SuppressLint("ValidFragment")
public PlaceDialogFragment(Place place, DisplayMetrics dm){
        super();
        this.mPlace = place;
        this.mMetrics = dm;
    }

Because of the nature of fragment and how there managed and shown on your screen it's very recommended not to create a non default constructor and in many cases this would cause problems in run time. In case you should do something like this:

public static final GridFragment newInstance(String tabId)
{
    GridFragment f = new GridFragment();
    Bundle bdl = new Bundle(2);
    bdl.putString(TAB_ID, tabId);
    f.setArguments(bdl);
    return f;
}

and in onCreate extract the needed data from the bundle:

@Override
public void onCreate(Bundle savedInstanceState) 
{
    String tabId = getArguments().getString(TAB_ID);
    }

And take a look at this question as well:

Do fragments really need an empty constructor?


@SuppressLint({"NewApi", "ValidFragment"})
public PlaceDialogFragment(Place place, DisplayMetrics dm){
        super();
      }

The easier way is to add these to the gradle:

android {
      lintOptions {
          checkReleaseBuilds false
      }
  }

Or you can add this line in each fragment

@SuppressLint("ValidFragment")
public PlaceDialogFragment(Place place, DisplayMetrics dm){
    super();
    this.mPlace = place;
    this.mMetrics = dm;
}

Best solution is add lines in gradle simply.


solution worked for me

android {
          lintOptions {
              checkReleaseBuilds false
          }
      }

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