GridView will keep to highlight the selected item

Question

My layout has a GridView. Similar to Google’s API demo, each grid has an image. Also, I customized a “Drawable image” which used to highlight the currently selected item. When touch the grid’s image, the “Drawable image” can be show. Unfortunately, it will disappear when I not touch the grid.

I hope the GridView will keep to highlight the selected item. Even the user is scrolling the screen.

From here, I found some similar post.

1) Keep image in GridView selected

2) Android gridview keep item selected

But I can’t understand their method and they are not using customized image. Can anyone give me some help? Please.

Following is my code:

    gridAdapter  adapter =  new   gridAdapter  (this, images);
    gv = (GridView) findViewById (R.id.gridView1);
    gv.setAdapter(adapter);
    gv.setSelector(R.drawable.circle);
    gv.setDrawSelectorOnTop(true);

Following is my updated code:

public class GridViewBasic extends Activity {
    Integer[] imageIDs = {
            R.drawable.ic_launcher,
            R.drawable.ic_launcher,
            R.drawable.ic_launcher,
            R.drawable.ic_launcher,
            R.drawable.ic_launcher,
            R.drawable.ic_launcher,
            R.drawable.ic_launcher,
            R.drawable.ic_launcher,
            R.drawable.ic_launcher,
            R.drawable.ic_launcher,
            R.drawable.ic_launcher,
            R.drawable.ic_launcher,
            R.drawable.ic_launcher,
            R.drawable.ic_launcher,
            R.drawable.ic_launcher    };
    GridView gridView;
    public int lastPos;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
            gridView = (GridView) findViewById(R.id.gridView1);
            gridView.setAdapter(new ImageAdapter(this));
            gridView.setSelected(true);
            gridView.setSelector(R.drawable.circle);
            gridView.setDrawSelectorOnTop(true);
            gridView.setDescendantFocusability(ViewGroup.FOCUS_AFTER_DESCENDANTS);

            gridView.setOnItemClickListener(new OnItemClickListener() {
                public void onItemClick(AdapterView<?> parent,  View v, int position, long id) {   
                    lastPos = position;
                    gridView.setSelection((int)(gridView.getAdapter()).getItemId(lastPos));
                    System.out.println ("getItemId ="+(gridView.getAdapter()).getItemId(lastPos));

                }
            });        
        }

        public class ImageAdapter extends BaseAdapter 
        {
            private Context context;

            public ImageAdapter(Context c)  {
                context = c;
            }

            //---returns the number of images---
            public int getCount() {
                return imageIDs.length;
            }

            //---returns the ID of an item--- 
            public Object getItem(int position) {
                return position;
            }

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

            //---returns an ImageView view---
            public View getView(int position, View convertView, ViewGroup parent) {
                ImageView imageView;

                if (convertView == null) {
                    imageView = new ImageView(context);
                    imageView.setLayoutParams(new GridView.LayoutParams(185, 185));
                    imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
                    imageView.setPadding(5, 5, 5, 5);
                } else {
                    imageView = (ImageView) convertView;
                }
                imageView.setImageResource(imageIDs[position]);

                return imageView;
            }
        }    


}

Answer 1

Ok now it needs a whole new answer...

here's the thing: setSelected() will set the calling view as selected, thus subsequently giving focus....

calling

 GridView gv; gv.setSelected(true);

will select the GridView gv, not the View in gridview's adapter which you want.

So you need to call gv.setSelection(pos) to select a specific child.

the pos you are saving might not be the real position but rather the position from 'visible' offset. that's why you have to call

(gridView.getAdapter()).getPosition(viewThatYouWant);

or

(gridView.getAdapter()).getItemAt(lastPos).requestFocus();

Do note that you should look into HOW A VIEW HANDLES IT'S FOCUS VS CHILD FOCUS the method is called

setDescendantFocusability

so naturally you would want

GridView gv; gv.setDescendantFocusability(ViewGroup.FOCUS_AFTER_DESCENDANTS);

Answer 2

public class StaffSelectionAdapter extends BaseAdapter {

private Context context;

private final String[] staffMemberList;
private int previousPosition = -1;
private static boolean isFirstTime;
boolean[] isChecked;
private TextView textView = null;
public long staffId;
private LayoutInflater inflater;


public StaffSelectionAdapter(Context context, String[] staffMemberList) {
    this.context = context;
    inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    this.staffMemberList = staffMemberList;

    isFirstTime = true;
    isChecked = new boolean[staffMemberList.length];
    for (int i = 0; i < staffMemberList.length; i++) {
        isChecked[i] = false;
    }
}

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

    if (convertView == null) {
        convertView = inflater.inflate(R.layout.row_for_staff_selection, null);
    }
    textView = (TextView) convertView.findViewById(R.id.row_for_staff_selection_grid_item_label);
    textView.setText(staffMemberList[position]);

    if (isChecked[position]) {
        SpannableString content = new SpannableString(staffMemberList[position]);
        content.setSpan(new UnderlineSpan(), 0, staffMemberList[position].length(), 0);
        textView.setText(content);
    } else {
        textView.setBackgroundColor(context.getResources().getColor(R.drawable.dialog_bg));
    }

    convertView.setTag(position);
    convertView.setOnClickListener(new OnClickListener() {

        public void onClick(View v) {
            if (!isChecked[position]) {
                staffId = 

                isChecked[position] = true;
                if (!isFirstTime) {
                    isChecked[previousPosition] = false;
                } else {
                    isFirstTime = false;
                }
                textView.setBackgroundColor(context.getResources().getColor(R.drawable.dialog_bg));
            }
            previousPosition = (Integer) v.getTag();
            notifyDataSetChanged();
        }
    });
    return convertView;
}

public int getCount() 
    {
    return staffMemberList.length;
}

public Object getItem(int position) 
    {
    return staffMemberList[position];
}

public long getItemId(int position) {
    return 0;
}

public long getStaffId() {
    return staffId;
}

public void setStaffId(long staffId) {
    this.staffId = staffId;
}

}

Answer 3

Set onItemClickListener on gridview .You can then get position of view onItemClick . pass the selected postion to adapter and within adapter inside getView method check if(position == selected_position) . if true set background of your choice .

public ColorGridAdapter(Context context,ArrayList<String> colorArray,int position) {
                super(context, resource,colorArray);            
                this.context = context;
                this.colors = colorArray;
                this.selected_position = position;  // position of your selected item

            }

    public View getView(final int position, View convertView, ViewGroup parent){
                View v = convertView;
                if (v == null) {

    LayoutInflater inflater = (LayoutInflater)  getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                        v = inflater.inflate(R.layout.color_pelatte, null);
                        ColorView = (View)v.findViewById(R.id.color_view);          
                    }

                ColorView.setBackgroundColor(Color.parseColor(colors.get(position)));
                if(position == selected_position){
                    v.setBackground(context.getResources().getDrawable(R.drawable.edittext_background));
                }

Answer 4

This is how I achieved this

 <GridView
    android:id="@+id/gv_calender"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:numColumns="7"
    android:listSelector="@color/colorAccent"
    android:stretchMode="columnWidth"></GridView>

and in Adapter add one line extra

  GridView gvCalender = (GridView)findViewById(R.id.gv_calender);
  CalendarAdapter adapter = new CalendarAdapter(getActivity(), lsCalender);
    gvCalender.setDrawSelectorOnTop(false);
    gvCalender.setAdapter(adapter);

That's It you are done
Key lines are

android:listSelector="@color/colorAccent"
AND
gvCalender.setDrawSelectorOnTop(false);