Why I cannot use Listview within Fragment

Question

How to use Listview within Fragment. I have implemented almost similar code in an Activity, there it worked perfectly. But in case of Fragment, I have only modified a little to avoid the errors showed by Android Studio. But, it's not working here. here is my code:

class FragmentMascot : Fragment() {
  override fun onCreateView(inflater: LayoutInflater?, container: ViewGroup?, savedInstanceState: Bundle?): View? {
    val view= inflater!!.inflate(R.layout.fragment_mascot, container, false)
    val listview = view.findViewById<ListView>(R.id.maskot_list)
    //listview.adapter = MaskotAdapter(this) -> this does't work in fragment but worked in activity
    listview.adapter = MaskotAdapter(context)
    return view
  }

and my MaskotAdapter class is:

private class MaskotAdapter(context: Context): BaseAdapter() {

    private val mContext: Context

    //values can be entered from database too.

    private val maskot_names_list = arrayListOf<String>("","","","")

    private val maskot_details_list = arrayListOf<String>("","","","")

    private val maskot_images_list = arrayListOf<Int>(0,0,0,0)

    init {
      this.mContext = context
    }
    //row count
    override fun getCount(): Int {
      return maskot_names_list.size //To change body of created functions use File | Settings | File Templates.
    }

    override fun getItem(position: Int): Any {
      return "test String" //To change body of created functions use File | Settings | File Templates.
    }

    override fun getItemId(position: Int): Long {
      return position.toLong()//To change body of created functions use File | Settings | File Templates.
    }
    //renders each row
    override fun getView(position: Int, convertView: View?, parent: ViewGroup?): View {
      val layoutInflater = LayoutInflater.from(mContext)
      val maskot_row=layoutInflater.inflate(R.layout.activity_maskot_fragment, parent, false)

      val maskot_names = maskot_row.findViewById<TextView>(R.id.maskot_name)
      maskot_names.text=maskot_names_list.get(position)

      // showing ??? if maskot name is empty
      // and giving it a little padding top, to not to keep it on top
      if(maskot_names.text=="")
      {
        maskot_names.text="？？？"
        maskot_names.setPadding( 0, 16, 0, 0)
      }

      val maskot_details = maskot_row.findViewById<TextView>(R.id.maskot_details)
      maskot_details.text=maskot_details_list.get(position)


      if(maskot_images_list.get(position)!=0)
      {
        // showing particular maskot image if maskot image is not empty
        val maskot_image = maskot_row.findViewById<ImageView>(R.id.maskot_image)
        maskot_image.setImageResource(maskot_images_list.get(position))
      }
      return maskot_row
    }
  }

U should use recycler view instead of ListView, which is more flexible and memory management. — amlwin, Jun 14 '18 at 04:01
This looks similar https://stackoverflow.com/questions/22512833/create-listview-in-fragment-android?utm_medium=organic&utm_source=google_rich_qa&utm_campaign=google_rich_qa — sneharc, Jun 14 '18 at 05:09

score 1 · Accepted Answer · answered Jun 18 '18 at 04:10

I found the answer at last. We need to activity as a parameter as well. So, in the code mentioned in the question:

listview.adapter = MaskotAdapter(context)

will be changed into listview.adapter = MaskotAdapter(context,activity) and

private class MaskotAdapter(context: Context): BaseAdapter() {

line should be changed into

private class MaskotAdapter(context: Context, activity: Activity): BaseAdapter() {

score 1 · Answer 2 · answered Jul 16 '18 at 03:47

Here, activity parameter is very important. You can change like:

listview.adapter = MaskotAdapter(context)

will be changed into

listview.adapter = MaskotAdapter(context,activity)

and

private class MaskotAdapter(context: Context): BaseAdapter() {

line should be changed into

private class MaskotAdapter(context: Context, activity: Activity): BaseAdapter() {

Hopefully, it will work. But, move to recyclerView if possible, as that is more memory efficient.

score 0 · Answer 3 · answered Jun 14 '18 at 03:40

0

You should use the Activity context (getActivity) in instantiating adapter. Fragment does not own a context.

answered Jun 14 '18 at 03:40

tompee

1,408
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6

score 0 · Answer 4 · answered Jun 14 '18 at 04:01

0

Does not the list appear? Or is there a fatal exception?

and,

Use RecyclerView. Calling inflate each time without using the holder pattern in getView () is an inefficient way.

answered Jun 14 '18 at 04:01

pistolcaffe

849
1
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1

please attach log. – pistolcaffe Jun 14 '18 at 04:40

Why I cannot use Listview within Fragment

4 Answers4