Ausgewählte Listenelement Hintergrundfarbe unerwartet wieder nach der Liste auf Tablets scrollen

Question

Für meine Listenansicht auf Tablets versuche ich, meine ausgewählte Listenelementauswahl zu erhalten, wenn sie ausgewählt wird, aber leider sehe ich ein seltsames Verhalten. Aus irgendeinem Grund, wenn ich durch die Liste bis zu dem Punkt scrolle, wo das ausgewählte Element nicht sichtbar ist, und dann zurück zu dem Punkt scrolle, wo das ausgewählte Element sichtbar ist, wird die Hintergrundfarbe unerwartet wiederverwendet. Ich glaube, dass etwas in der getView-Methode gehen muss, aber ich bin mir nicht sicher, was ich mit dieser Methode machen soll. Was muss getan werden, damit die Hintergrundfarbe nicht wiederverwendet wird?

Adapter Klasse

public class VictoriaListAdapter extends BaseAdapter { 

    private List<Victoria> mData; 
    private LayoutInflater mInflater; 

    public VictoriaListAdapter (List<Victoria> data, Context context) { 
     mData = data; 
     mData = new ArrayList(mData); 
     mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
    } 

    @Override 
    public int getCount() { 
     return mData.size(); 
    } 

    @Override 
    public String getItem(int position) { 
     return mData.get(position).getStation(); 
    } 

    @Override 
    public long getItemId(int position) { 
     return position; 
    } 

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

     ViewHolder holder; 

     if (convertView == null) { 
      convertView = mInflater.inflate(R.layout.list_item_dualline, parent, false); 
      holder = new ViewHolder(); 

      holder.title = (TextView) convertView.findViewById(R.id.item_station); 
      holder.description = (TextView) convertView.findViewById(R.id.item_zone); 

      convertView.setTag(holder); 
     } else { 
      holder = (ViewHolder) convertView.getTag(); 
     } 

     holder.title.setText(mData.get(position).getStation()); 
     holder.description.setText(mData.get(position).getZone()); 

     return convertView; 
    } 

    /** 
    * View holder 
    */ 
    static class ViewHolder { 
     private TextView title; 
     private TextView description; 
    } 
} 

Fragment Klasse

public class FragmentVictoriaLine extends ListFragment { 

    private VictoriaListAdapter mAdapter; 

    public FragmentVictoriaLine() { 
    } 

    /** 
    * Whether or not the activity is in two-pane mode, i.e. running on a tablet 
    * device. 
    */ 
    public boolean mTwoPane; 

    public static FragmentVictoriaLine newInstance() { 
     return new FragmentVictoriaLine(); 
    } 

    @Nullable 
    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
     View view = inflater.inflate(R.layout.fragment_victoria_line, container, false); 
     initialize(); 
     return view; 
    } 

    List<Victoria> list = new ArrayList<>(); 
    private void initialize() { 
     String[] items = getActivity().getResources().getStringArray(R.array.victoria_stations); 
     String[] itemDescriptions = getActivity().getResources().getStringArray(R.array.victoria_zones); 
     for (int n = 0; n < items.length; n++){ 
      Victoria victoria = new Victoria(); 
      victoria.setID(); 
      victoria.setStation(items[n]); 
      victoria.setZone(itemDescriptions[n]); 
      list.add(victoria); 
     } 

     mAdapter = new VictoriaListAdapter(list, getActivity()); 
     setListAdapter(mAdapter); 
    } 

    @Override 
    public void onActivityCreated(Bundle savedInstanceState) { 
     View v = getView(); 

     mTwoPane = getActivity().findViewById(R.id.detail_container) != null; 

     assert v != null; 
     ListView lv = (ListView)v.findViewById(android.R.id.list); 
     lv.setOnItemClickListener(new AdapterView.OnItemClickListener() { 
      private Victoria selectedMain; 
      private View selectedView; 

      @Override 
      public void onItemClick(AdapterView<?> parent, View view, int position, long id) { 
       VictoriaListAdapter adapter = (VictoriaListAdapter) parent.getAdapter(); 
       String station = adapter.getItem(position); 

       if (mTwoPane) { 
        setItemNormal(); 
        View rowView = view; 
        setItemSelected(rowView); 

        Fragment newFragment; 
        if (station.equals(view.getResources().getString(R.string.bho))) { 
         newFragment = new FragmentVictoriaBHO(); 
        } else if (station.equals(view.getResources().getString(R.string.brx))) { 
         newFragment = new FragmentVictoriaBRX(); 
        } else if (station.equals(view.getResources().getString(R.string.eus))) { 
         newFragment = new FragmentVictoriaEUS(); 
        } else if (station.equals(view.getResources().getString(R.string.fpk))) { 
         newFragment = new FragmentVictoriaFPK(); 
        } else if (station.equals(view.getResources().getString(R.string.green_park))) { 
         newFragment = new FragmentVictoriaGreenPark(); 
        } else if (station.equals(view.getResources().getString(R.string.hhy))) { 
         newFragment = new FragmentVictoriaHHY(); 
        } else if (station.equals(view.getResources().getString(R.string.kxsp))) { 
         newFragment = new FragmentVictoriaKXSP(); 
        } else { 
         newFragment = new FragmentVictoriaBHO(); 
        } 
        VictoriaLineActivity activity = (VictoriaLineActivity) view.getContext(); 
        FragmentTransaction transaction = activity.getSupportFragmentManager().beginTransaction(); 
        transaction.setCustomAnimations(R.anim.fade_out, R.anim.fade_in); 
        transaction.replace(R.id.detail_container, newFragment); 
        transaction.commit(); 
       } else { 
        Intent intent; 
        if (station.equals(view.getResources().getString(R.string.bho))) { 
         intent = new Intent(getActivity(), VictoriaBHOActivity.class); 
        } else if (station.equals(view.getResources().getString(R.string.brx))) { 
         intent = new Intent(getActivity(), VictoriaBRXActivity.class); 
        } else if (station.equals(view.getResources().getString(R.string.eus))) { 
         intent = new Intent(getActivity(), VictoriaEUSActivity.class); 
        } else if (station.equals(view.getResources().getString(R.string.fpk))) { 
         intent = new Intent(getActivity(), VictoriaFPKActivity.class); 
        } else if (station.equals(view.getResources().getString(R.string.green_park))) { 
         intent = new Intent(getActivity(), VictoriaGreenParkActivity.class); 
        } else if (station.equals(view.getResources().getString(R.string.hhy))) { 
         intent = new Intent(getActivity(), VictoriaHHYActivity.class); 
        } else if (station.equals(view.getResources().getString(R.string.kxsp))) { 
         intent = new Intent(getActivity(), VictoriaKXSPActivity.class); 
        } else { 
         intent = new Intent(getActivity(), VictoriaBHOActivity.class); 
        } 
        startActivity(intent); 
       } 
      } 

      public void setItemSelected(View view) { 
       View rowView = view; 
       view.setBackgroundColor(Color.parseColor("#868F98")); 

       TextView tv0 = (TextView) rowView.findViewById(R.id.item_station); 
       tv0.setTextColor(Color.WHITE); 

       TextView tv1 = (TextView) rowView.findViewById(R.id.item_zone); 
       tv1.setTextColor(Color.WHITE); 
      } 

      public void setItemNormal() { 
       for (int i = 0; i < getListView().getChildCount(); i++) { 
        View v = getListView().getChildAt(i); 
        v.setBackgroundColor(Color.TRANSPARENT); 

        TextView tv0 = ((TextView) v.findViewById(R.id.item_station)); 
        tv0.setTextColor(Color.WHITE); 

        TextView tv1 = ((TextView) v.findViewById(R.id.item_zone)); 
        tv1.setTextColor(Color.parseColor("#B5B5B5")); 
       } 
      } 
     }); 

     super.onActivityCreated(savedInstanceState); 
    } 
} 

Datenklasse

public class Victoria { 
    public Victoria(){} 

    private String station; 
    private String zone; 
    private boolean selected; 

    public String getStation(){ 
     return station; 
    } 

    public void setStation(String item){ 
     this.station = item; 
    } 

    public String getZone(){ 
     return zone; 
    } 

    public void setZone(String zone){ 
     this.zone = zone; 
    } 

    private int _id; 
    public void getID(int _id){ 
     this._id = _id; 
    } 

    public int setID(){ 
     return _id; 
    } 

    public boolean isSelected() { 
     return selected; 
    } 

    public void setSelected(boolean selected) { 
     this.selected = selected; 
    } 
} 

Answer 1

beim Blättern durch Liste, werden die Elemente/Ansichten in ListView wiederverwendet, um den Speicher zu optimieren. Wenn Sie einen ausgewählten Status auf ein Listenelement festlegen, wird der ausgewählte Status in mehreren Listenelementen beim Blättern angezeigt. Der beste Weg, dies zu verhindern, ist, den Zustand in Ihrem Datenmodell zu erhalten und den Zustand in getView Funktion der Adapter zu setzen.

Hier ist, was Sie tun können -

@Override 
public void onItemClick(AdapterView<?> parent, View view, int position,long id) { 
    VictoriaListAdapter adapter = (VictoriaListAdapter) parent.getAdapter(); 

    //reverse the selected state in data model 
    for (int i = 0; i < adapter.getCount(); i++) { 
    Victoria victoria = (Victoria)adapter.getItem(i); 
    victoria.setSelected(i == position ? true : false); 
    } 
    Victoria victoria = (Victoria)adapter.getItem(position); 

    --- 
    --- 

Und in Adapter -

@Override 
public Object getItem(int position) { 
    //Return full object, coz we need to access other 
    //member variables too 
    return mData.get(position); 
} 

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

    ViewHolder holder; 

    if (convertView == null) { 
     convertView = mInflater.inflate(R.layout.list_item_dualline, parent, false); 
     holder = new ViewHolder(); 

     holder.title = (TextView) convertView.findViewById(R.id.item_station); 
     holder.description = (TextView) convertView.findViewById(R.id.item_zone); 

     convertView.setTag(holder); 
    } else { 
     holder = (ViewHolder) convertView.getTag(); 
    } 

    Victoria victoria = (Victoria)getItem(position); 
    holder.title.setText(victoria.getStation()); 
    holder.description.setText(victoria.getZone()); 
    if (victoria.isSelected()) { 
     setItemSelected(convertView); 
    } else { 
     setItemNormal(convertView); 
    } 

    return convertView; 
} 

public void setItemSelected(View view) { 
    View rowView = view; 
    view.setBackgroundColor(Color.parseColor("#868F98")); 

    TextView tv0 = (TextView) rowView.findViewById(R.id.item_station); 
    tv0.setTextColor(Color.WHITE); 

    TextView tv1 = (TextView) rowView.findViewById(R.id.item_zone); 
    tv1.setTextColor(Color.WHITE); 
} 

public void setItemNormal(View v) { 

    v.setBackgroundColor(Color.TRANSPARENT); 

    TextView tv0 = ((TextView) v.findViewById(R.id.item_station)); 
    tv0.setTextColor(Color.WHITE); 

    TextView tv1 = ((TextView) v.findViewById(R.id.item_zone)); 
    tv1.setTextColor(Color.parseColor("#B5B5B5")); 

} 

Hoffe, es hilft!