如何从另一个类更改imageview源？

Question

I have 2 classes, the first is FragmentA and the second is ListRequestAdapter (ArrayAdapter). I wanted to change an ImageView in ListRequestAdapter from my FragmentA . But I always get an error NullPointerException when I declare the ImageView in my FragmentA . How could I do that?

Here is my code:

FragmentA.java class:

 public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_item_list_request, container, false);
    setHasOptionsMenu(true);


    listPhoto = (ImageView) getView().findViewById(R.id.listPhoto);
    listPhoto.setImageResource(R.drawable.pastel_blue);

    }

ListRequestAdapter.java class:

public class ListRequestAdapter extends ArrayAdapter<ListRequestItem> {
ImageView listPhoto;

public ListRequestAdapter(Context context, List<ListRequestItem> items)
{
    super(context, R.layout.style_fragment_list_request, items);

}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    ViewHolder viewHolder;

    if(convertView == null) {
        // inflate the GridView item layout
        LayoutInflater inflater = LayoutInflater.from(getContext());
        convertView = inflater.inflate(R.layout.style_fragment_list_request,  parent, false);

        // initialize the view holder
        viewHolder = new ViewHolder();
        viewHolder.tvTanggal = (TextView) convertView.findViewById(R.id.tvTanggalRequest);
        viewHolder.tvTipe = (TextView) convertView.findViewById(R.id.tvTipeRequest);
        viewHolder.tvStatus = (TextView) convertView.findViewById(R.id.tvStatus);
        viewHolder.permitid = "";
        convertView.setTag(viewHolder);
    } else {
        // recycle the already inflated view
        viewHolder = (ViewHolder) convertView.getTag();
    }

    // update the item view
    ListRequestItem item = getItem(position);
    viewHolder.tvTanggal.setText(item.tanggal);
    viewHolder.tvTipe.setText(item.tipe);
    viewHolder.tvStatus.setText(item.status);
    viewHolder.permitid = item.permitid;
    return convertView;
}

private static class ViewHolder {
    TextView tvTanggal;
    TextView tvTipe;
    TextView tvStatus;
    String permitid;
}
}

List item's layout:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:tag="reqtag"
android:id="@+id/rlListRequestWorkflow"
>
<LinearLayout
    android:layout_width="match_parent"
    android:orientation="horizontal"
    android:weightSum="1"
    android:layout_height="match_parent">

    <LinearLayout
        android:layout_width="0dp"
        android:layout_weight="0.2"
        android:orientation="vertical"
        android:layout_height="wrap_content">

        <!--ImageView here-->
        <de.hdodenhof.circleimageview.CircleImageView
            android:id="@+id/listPhoto"
            android:layout_width="65dp"
            android:layout_height="63dp"
            android:layout_weight="1"
            android:layout_gravity="center_horizontal"
            android:src="@drawable/ic_menu_camera"
            android:layout_marginTop="10dp" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="0dp"
        android:layout_weight="0.8"
        android:orientation="vertical"
        android:layout_height="wrap_content">

        <!--All textViews here-->
        <TextView
            android:layout_width="100dp"
            android:layout_weight="1"
            android:layout_height="wrap_content"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:text="Type"
            android:textSize="18dp"
            android:fontFamily="sans-serif"
            android:textColor="@color/black"
            android:id="@+id/tvTipeRequest"
            android:width="130dp" />

        <TextView
            android:layout_width="100dp"
            android:layout_weight="1"
            android:layout_height="wrap_content"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:text="Date"
            android:fontFamily="sans-serif"
            android:id="@+id/tvTanggalRequest"
            android:textSize="15dp"
            android:width="130dp" />

        <TextView
            android:layout_width="100dp"
            android:layout_weight="1"
            android:layout_height="50dp"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:textColor="@color/black"
            android:text="Status"
            android:textSize="15dp"
            android:fontFamily="sans-serif"
            android:id="@+id/tvStatus"
            android:layout_column="38" />
    </LinearLayout>

</LinearLayout>

Answer 1

You answer does not help you to upate the ImageView in the ListView. You just make a new View (anotherView) which is not related to anything. To update your ImageView in the ListView, you should have some related info (ImageID or ImagePath etc) in your DataList. After the info is set/updated, just call adapter.notifyDataSetChanged() inside your Fragment.

In addition, you may modify your ListRequestAdapter to hide the ImageView if no data, like this:

public class ListRequestAdapter extends ArrayAdapter<ListRequestItem> {

    public ListRequestAdapter(Context context, List<ListRequestItem> items){
        super(context, R.layout.style_fragment_list_request, items);
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder viewHolder;
        if(convertView == null) {
            // inflate the GridView item layout
            LayoutInflater inflater = LayoutInflater.from(getContext());
            convertView = inflater.inflate(R.layout.style_fragment_list_request,  parent, false);
            // initialize the view holder
            viewHolder = new ViewHolder();
            viewHolder.imgPhoto = (ImageView) convertView.findViewById(R.id.listPhoto);
            viewHolder.tvTanggal = (TextView) convertView.findViewById(R.id.tvTanggalRequest);
            viewHolder.tvTipe = (TextView) convertView.findViewById(R.id.tvTipeRequest);
            viewHolder.tvStatus = (TextView) convertView.findViewById(R.id.tvStatus);
            viewHolder.permitid = "";
            convertView.setTag(viewHolder);
        } else {
            // recycle the already inflated view
            viewHolder = (ViewHolder) convertView.getTag();
        }
        // update the item view
        ListRequestItem item = getItem(position);

        // Setup ImageView accord to DataList,
        // may be imageID from DataList.
        if(imageID == null) viewHolder.imgPhoto.setVisibility(View.INVISIBLE);
        else{
             viewHolder.imgPhoto.setImageResource(item.imageID);
             viewHolder.setVisibility(VIEW_VISIBLE);
        }

        viewHolder.tvTanggal.setText(item.tanggal);
        viewHolder.tvTipe.setText(item.tipe);
        viewHolder.tvStatus.setText(item.status);
        viewHolder.permitid = item.permitid;
        return convertView;
    }

    private static class ViewHolder {
        ImageView imgPhoto;
        TextView tvTanggal;
        TextView tvTipe;
        TextView tvStatus;
        String permitid;
    }
}

Hope this help!

Answer 2

Problem solved by just inflating the layout that contains the ImageView like this:

View anotherView =     inflater.inflate(R.layout.style_fragment_list_request,container,false);
imgView = (ImageView)anotherView.findViewById(R.id.listPhoto);`