Develop Reference

Android custom ArrayAdapter rendering Objects in list, not values

I'm trying to bind a custom layout (a LinearLayout containing two TextViews) to a Spinner. I subclassed ArrayAdapter (mostly) correctly. Selecting an item in the Spinner calls getView() correctly, setting the LinearLayout's TextViews' values correctly. The problem is the initial display of the items in the Spinner (when clicking on the Spinner) just shows Objects; not the TextViews they should be displaying. Only AFTER clicking on one of the Objects does the Spinner correctly set the TextViews using my custom adapter's getView() method. Here's the custom adapter class:
public class BusRouteAdapter extends ArrayAdapter<BusRoute> {
...
public BusRouteAdapter(Context context, int resource, int textViewId, ArrayList<BusRoute> routes) {
super(context, resource, textViewId, routes);
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
BusRoute route = getItem(position);
if (convertView == null) {
convertView = LayoutInflater.from(getContext()).inflate(R.layout.bus_route, parent, false);
}
TextView tvBusRoute = (TextView) convertView.findViewById(R.id.tvBusRoute);
TextView tvBusRouteNumber = (TextView) convertView.findViewById(R.id.tvBusRouteNumber);
tvBusRoute.setText(route.routeName);
tvBusRoute.setTag(route.route);
tvBusRouteNumber.setText(route.route);
if (!route.routeColor.equals("")) {
tvBusRouteNumber.setBackgroundColor(Color.parseColor(route.routeColor));
}
return convertView;
}
}
Here's the layout that is to be used for each Spinner list item (bus_route.xml):
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:weightSum="1">
<TextView
android:id="#+id/tvBusRouteNumber"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="0.25"
android:padding="8dp" />
<TextView
android:id="#+id/tvBusRoute"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="0.75"
android:padding="8dp" />
</LinearLayout>
And in my Activity, I'm setting the adapter to a properly-populated list of BusRoute objects:
busRouteAdapter = new BusRouteAdapter(getBaseContext(), R.layout.bus_route, R.id.tvBusRoute, arrayOfBusRoutes);
routesSpinner.setAdapter(busRouteAdapter);
It does seem strange that I need to pass the Layout id (R.layout.bus_route) AND one of the TextViews contained in that Layout (R.id.tvBusRoute).
Here's what is rendered when clicking on the Spinner:
But if I click one of the Objects, getView() is called, and the selected Layout and TextViews are rendered properly (apparently I selected "GMU - Pentagon"):
What am I missing to get the Spinner's popup list to display ALL my bus route items rendered correctly?

I think you need to override getDropDownView to deal with spinners
#Override
public View getDropDownView(int position, View convertView, ViewGroup parent) {
BusRoute route = getItem(position);
if (convertView == null) {
convertView = LayoutInflater.from(getContext()).inflate(R.layout.bus_route, parent, false);
}
TextView tvBusRoute = (TextView) convertView.findViewById(R.id.tvBusRoute);
TextView tvBusRouteNumber = (TextView) convertView.findViewById(R.id.tvBusRouteNumber);
tvBusRoute.setText(route.routeName);
tvBusRoute.setTag(route.route);
tvBusRouteNumber.setText(route.route);
if (!route.routeColor.equals("")) {
tvBusRouteNumber.setBackgroundColor(Color.parseColor(route.routeColor));
}
return convertView;
}

Change ImageView in a GridView Programmatically

I've set up a grid of ImageViews with TextView overlays. My ImageAdapter code is as follows:
public View getView(int position, View convertView, ViewGroup parent) {
ImageView imageView;
View grid;
LayoutInflater inflater = (LayoutInflater) mContext
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
if (convertView == null) {
grid = new View(mContext);
grid = inflater.inflate(R.layout.image, null);
TextView textView = (TextView)grid.findViewById(R.id.mastery_text);
imageView = (ImageView)grid.findViewById(R.id.mastery_image);
grid.setLayoutParams(new GridView.LayoutParams(150, 150));
imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
grid.setPadding(8, 8, 8, 8);
grid.setBackgroundResource(R.color.orange);
imageView.setImageResource(mThumbIds[position]);
} else {
grid = (View) convertView;
}
return grid;
}
The corresponding XML layout for my ImageAdapter is this:
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/layout_practitioner"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<ImageView
android:id="#+id/mastery_image"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scaleType="centerCrop"
/>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:layout_gravity="bottom"
android:background="#bbffffff"
android:focusable="false"
android:focusableInTouchMode="false" >
<TextView android:id="#+id/mastery_text"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="0dp"
android:textColor="#color/black"
android:gravity="bottom|center"
android:textSize="12sp"
android:textAllCaps="true"
android:paddingBottom="0dp"
android:text="3/3"
/>
</LinearLayout>
</FrameLayout>
XML code for my GridView (activity class):
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<GridView xmlns:android="http://schemas.android.com/apk/res/android"
android:paddingTop="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:id="#+id/gridview"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:numColumns="4"
android:verticalSpacing="10dp"
android:horizontalSpacing="10dp"
android:stretchMode="columnWidth"
android:gravity="center" />
</LinearLayout>
Here is the onCreate method of my main activity:
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_masteries);
GridView gridview = (GridView) findViewById(R.id.gridview);
ImageAdapter adapter = new ImageAdapter(this);
gridview.setAdapter(adapter);
gridview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View v,
int position, long id) {
Toast.makeText(Masteries.this, "" + position,
Toast.LENGTH_SHORT).show();
}
});
}
I want to, after initializing the grid with the images, change one of the ImageViews from my activity class, given its position on the grid. How would I do that?
I'm not asking to change the image in response to an onItemClick.
Thanks in advance!
Edit:
I'm thinking of creating a changeImage(int position, int imageId) method in my Adapter and calling that from my activity class. Is that the right approach?

In your adapter:
public void updateImage(int position, int resourceId)
{
mThumbIds[position] = resourceId;
notifyDataSetChanged();
}
In your activity:
mAdapter.updateImage(<position>, <image_resource_id>);
Notes
You will have to make the adapter a member of your activity
The main idea is that you modify the backing data and and notify the GridView that this has changed and it is time to be redrawn
Your getView() method implementation needs a lot of improvement. It will cause lots of bugs once the system starts recycling the views (the convertView parameter comes in != null for a position different than it was used for last time)
Here's a sketch of how your getView() should look like:
#Override
public View getView(int position, View convertView, ViewGroup parent)
{
ViewHolder viewHolder;
LayoutInflater inflater = (LayoutInflater)mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
if (convertView == null) {
convertView = inflater.inflate(R.layout.image, parent, false);
// next three lines would not be necessary if:
// a) it is the same for every item;
// b) you inflate properly (using the parent);
// c) you specify this in the item's xml (R.layout.image)
convertView.setLayoutParams(new GridView.LayoutParams(150, 150));
convertView.setPadding(8, 8, 8, 8);
convertView.setBackgroundResource(android.R.color.holo_red_light);
viewHolder = new ViewHolder();
viewHolder.mTextView = (TextView)convertView.findViewById(R.id.mastery_text);
viewHolder.mImageView = (ImageView)convertView.findViewById(R.id.mastery_image);
// this could also be set in xml perhaps
viewHolder.mImageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
convertView.setTag(viewHolder);
} else {
viewHolder = (ViewHolder)convertView.getTag();
}
// update the values every time we are being asked to update the item,
// because the item might have been reused from a different position
viewHolder.mImageView.setImageResource(mThumbIds[position]);
//viewHolder.mTextView.setText("myText");
return convertView;
}
public static class ViewHolder
{
TextView mTextView;
ImageView mImageView;
}

You can set a unique id to each ImageView using names (See here) or even integer numbers with a sequence or something (increasing at each image you put in the view).
Another good way to do this is using the tags, with setTag() and getTag().
This question has a good answer: What is the main purpose of setTag() getTag() methods of View?

Dynamic Grid Layout

I want to implement grid, which will be populated dynamically. I want to know what is the best approach to implement this Relative layout(List View) or Grid Layout?

You can generate a GridView dynamically.
GridView would contain of ImageView and TextView as per your need. You will have to use your custom adapter. In it's getView method, populate the ImageView and TextView.
Example:
GridView item.xml:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<ImageView
android:id="#+id/imgItem"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:src="#drawable/ic_launcher" />
<TextView
android:id="#+id/txtItem"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:fontFamily="trebuchet"
android:textColor="#android:color/black"
android:textSize="15sp"
android:textStyle="bold" />
</LinearLayout>
Java code:
A POJO class for item:
public class Item
{
String title;
Drawable image;
//getter setter
}
Adapter class:
//getView method in your adapter class
#Override
public View getView(int position, View convertView, ViewGroup parent)
{
View itemView = convertView;
ViewHolder holder = null;
if (itemView == null)
{
final LayoutInflater layoutInflater =
(LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
itemView = layoutInflater.inflate(resourceId, parent, false);
holder = new ViewHolder();
holder.imgItem = (ImageView) itemView.findViewById(R.id.imgItem);
holder.txtItem = (TextView) itemView.findViewById(R.id.txtItem);
itemView.setTag(holder);
}
else
{
holder = (ViewHolder) itemView.getTag();
}
Item item = getItem(position);
holder.imgItem.setImageDrawable(item.getImage());
holder.txtItem.setText(item.getTitle());
return itemView;
}
Now add adapter data in your Activity class and then set that adapter to GridView.
Refer to this and this
Hope it helps.

Simply use GridView with a custom adapter. Each time you want the view to update, call notifyDataSetChanged() on the adapter.

You want GridView. Easy example here. In your case, you will need to make an XML layout for each row to accommodate both your TextView and ImageView. Other answers here address that.

Using customlistviews in android : Keep on getting list view = NULL

I am new to android and am trying to create two fragments and have it so you can slide between the two, one is a list and the otehr a grid. I had the list working when it when I was using an ArrayAdapter and had my EventListFragment extending ListFragment (if code is helpful let me know and ill post that part)
I am now trying to create a custom list view with multiline list items (let me know if there is an easier way and if i have simply overcomplicated the whole thing)
Here is my code:
Event List Fragment:
public class EventListFragment extends Fragment {
ArrayList<EventObject> eventObjects;
#Override
public View onCreateView (LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
eventObjects = ((EventsActivity)getActivity()).getEventObjects();
View view = inflater.inflate(R.layout.eventgrid ,container,false);
Listview listView = (ListView) view.findViewById(R.id.listView);
if (listView == null) {
System.out.println("asas");
}
listView.setAdapter(new MyCustomBaseAdapter(getActivity().getBaseContext(), eventObjects));
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> a, View v, int position, long id) {
Object o = listView.getItemAtPosition(position);
EventObject fullObject = (EventObject)o;
System.out.println("asd");
}
});
return view;
}
}
The corresponding xml:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<android.support.v4.view.ViewPager
android:id="#+id/viewpager"
android:layout_width="fill_parent"
android:layout_height="fill_parent" />
<ListView
android:id="#+id/listView"
android:layout_height="wrap_content"
android:layout_width="fill_parent"/>
</RelativeLayout>
The xml for the customgridrow:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<TextView android:id="#+id/name"
android:textSize="14sp"
android:textStyle="bold"
android:textColor="#FFFF00"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
<TextView android:id="#+id/cityState"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
<TextView android:id="#+id/phone"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
</LinearLayout>
EDIT
The getView() from MyCustomBaseAdapter :
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
if (convertView == null) {
convertView = mInflater.inflate(R.layout.customgridrow, null);
holder = new ViewHolder();
holder.txtName = (TextView) convertView.findViewById(R.id.name);
holder.txtCityState = (TextView) convertView.findViewById(R.id.cityState);
holder.txtPhone = (TextView) convertView.findViewById(R.id.phone);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
holder.txtName.setText(events.get(position).getName());
holder.txtCityState.setText(events.get(position).getDate());
holder.txtPhone.setText(events.get(position).getVenue());
return convertView;
}

From your comments
You are inflating the wrong layout
You should inflate the one that has listview and initialize the same.
Change
View view = inflater.inflate(R.layout.eventgrid ,container,false);
to
View view = inflater.inflate(R.layout.eventList ,container,false);

Every time you want to add an object to a list, you have to provide a view for the object. Android asks your list adapter, be it custom or system-defined, it asks the adapter what each list item is supposed to look like. This is where getView() comes into play.
public abstract View getView (int position, View convertView, ViewGroup parent):
Get a View that displays the data at the specified position in the data set.
If convertView is null, you will get an NPE.
Tutorials here: http://www.javacodegeeks.com/2013/06/android-listview-tutorial-and-basic-example.html

Overlay onto a gridview

I have a gridview I created using this tutorial GridView Android, which works just fine. Now I'd like to overlay an image onto the item of the gridview if say the item is clicked. I'm not sure how to do this, whether I use another gridview and merge them or just have lots of image views :s. Just to clarify the question: How do I overlay onto gridview items? Thanks in advance!

So there are a few ways you might achieve this but possibly the most flexible would be to use a custom view in the getView method.
Add a LayoutInflater to your ImageAdapter class:
private LayoutInflater mInflater;
Initialize it in the constructor:
public ImageAdapter(Context c) {
mContext = c;
// Initialise the inflater
mInflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
This is used to inflate an xml view such as this:
<RelativeLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<ImageView
android:id="#+id/mainImage"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
/>
<ImageView
android:id="#+id/overlayImage"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:visibility="gone"
/>
</RelativeLayout>
Inflate this view in the ImageAdapter class getView method
public View getView(int position, View convertView, ViewGroup parent) {
// RelativeLayout as used in the xml view
RelativeLayout customView;
if (convertView == null) { // if it's not recycled, inflate
customView = (RelativeLayout) mInflater.inflate(R.layout.customview, null);
} else {
imageView = (RelativeLayout) convertView;
}
// Get the mainImageView from the parent
ImageView mainImage = (ImageView) customView.findViewById(R.id.mainImage);
imageView.setImageResource(mThumbIds[position]);
// Overlay view
ImageView overlayImage = (ImageView) customView.findViewById(R.id.overlayImage);
overlayImage.setImageResource(mOverlayThumbIds[position]); // new array containing overlay references
return customView;
}
Then show the overlay image on click
gridview.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
ImageView overlayImage = (ImageView) v.findViewById(R.id.overlayImage);
overlayImage.setVisibility(View.VISIBLE);
}
});
This is a very basic example but hopefully you will find the approach useful.