Develop Reference

Android Studio: Simple BaseAdapter Setup Fail

I would like to create a simple populated GridView using BaseAdapter but I keep getting empty list - application runs but there are no Views displayed.
Below are all files are use for this task:
Main:
String[] items = {"Some", "items", "to", "display"};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
GridView grid = (GridView)findViewById(R.id.grid);
final TextView text = (TextView)findViewById(R.id.text);
MyAdapter adapter = new MyAdapter(getApplicationContext(), items);
grid.setAdapter(adapter);
MyAdapter:
LayoutInflater inflater;
Context context;
String[] myData;
public MyAdapter(Context context, String[] myData) {
this.context = context;
this.myData = myData;
}
#Override
public int getCount() {
return 0;
}
#Override
public Object getItem(int position) {
return myData[position];
}
#Override
public long getItemId(int position) {
return 0;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
convertView = inflater.inflate(R.layout.grid, parent, false);
TextView text = (TextView) convertView.findViewById(R.id.textView);
text.setText(myData[position]);
return convertView;
}
activity_main.xml:
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.android.random.MainActivity">
<GridView
android:id="#+id/grid"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:verticalSpacing="40dip"
android:horizontalSpacing="5dip"
android:numColumns="auto_fit"
android:columnWidth="100dip"
android:stretchMode="columnWidth"
android:gravity="center"
/>
</android.support.constraint.ConstraintLayout>
grid.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="#+id/textView"
android:layout_width="wrap_content"
android:layout_height="match_parent"
/>
</LinearLayout>
I have checked in various sources countles times and I did not manage to find an error in my code. It would be amazing if someone would take a look at it and find a reason for empty activity as the reason is probably obvious.

Your getCount method always return 0. Return the number of elements in your myData array instead.
#Override
public int getCount() {
return myData.length;
}

You can try this my friend
public class MyAdapter extends BaseAdapter {
Context context;
String[] data;
public MyAdapter(Context context, String[] myData) {
this.context = context;
this.data = myData;
}
#Override
public int getCount() {
return data.length;
}
#Override
public Object getItem(int position) {
return data[position];
}
#Override
public long getItemId(int position) {
return position;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
if (convertView == null) {
LayoutInflater mInflater = (LayoutInflater)
context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
convertView = mInflater.inflate(R.layout.grid, null);
}
TextView text = (TextView) convertView.findViewById(R.id.textView);
text.setText(data[position]);
return convertView;
}
}

Android viewpager is not loading the Image?

I asked very similar question in the morning but after trying something viewpager is not loading the expected images. This is my updated code:
layout_view_pager_item
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:id="#+id/image"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:background="#000000"
android:padding="1dp" />
</LinearLayout>
layout_data_listing_food
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
style="#style/Base.TextAppearance.AppCompat.Menu"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<TextView
.....
android:focusable="true" />
<android.support.v4.view.ViewPager
android:id="#+id/pager"
....
android:layout_alignStart="#id/profilePic" />
FoodListAdapter
public class FoodListAdapter extends ArrayAdapter<Food> {
private Context context;
private List<Food> roomList;
private ViewPager viewPager;
ArrayList<Integer> itemsimg = new ArrayList<Integer>();
public FoodListAdapter(Context context, int resource, List<Food> objects) {
super(context, resource, objects);
this.context = context;
this.roomList = objects;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
itemsimg.add(R.drawable.temp_envelope);
LayoutInflater inflater = (LayoutInflater) context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
if (null == convertView) {
convertView = inflater.inflate(R.layout.layout_data_listing_food, parent, false);
}
ViewPageAdapter slider = new ViewPageAdapter(context,itemsimg);
ViewPager vpPager = (ViewPager) convertView.findViewById(R.id.pager);
vpPager.setAdapter(slider);
return convertView;
}
}
ViewPagerAdapter
public class ViewPageAdapter extends PagerAdapter {
private ArrayList<Integer> pagerItems;
private LayoutInflater inflater;
private Context context;
private FragmentManager fragmentManager;
public ViewPageAdapter(Context context, ArrayList<Integer> pagerItems) {
super();
this.pagerItems = pagerItems;
this.context = context;
inflater = LayoutInflater.from(context);
}
#Override
public Object instantiateItem(ViewGroup container, int position) {
try {
View imageLayout = inflater.inflate(R.layout.layout_view_pager_item, container, false);
final ImageView imageView = (ImageView) imageLayout
.findViewById(R.id.image);
imageView.setImageResource(pagerItems.get(position));
container.addView(imageLayout, 0);
return imageLayout;
}catch (Exception ex){
ex.printStackTrace();
return null;
}
}
#Override
public int getCount() {
return pagerItems.size();
}
#Override
public boolean isViewFromObject(View view, Object object) {
return view.equals(object);
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
((ViewPager) container).removeView((View) object);
}
}
Expectation
List view should have to show viewpager data in each row (Right now I hardcoded the viewpager data)
Each row will contain Viewpager and TextView as we can see in layout_data_listing_food ViewPager ImageView just after the TextView
What I am doing wrong here? When I debug the code there was not Error :(
and data is also passing from one class to another. Any help would be appreciable
Problem
I can't see the Image loading through Viewpager but I can see the TextView content in layout file

Adding Textviews to ViewPager present in a ListView but the textviews are not visible

Layout of the row of list view:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent" android:id="#+id/linearLayout_template3">
<TextView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/template3_textView"/>
<android.support.v4.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/pager"
android:layout_width="match_parent"
android:layout_height="200dp"
android:orientation ="horizontal" />
</LinearLayout>
ListView Adapter:
Here I am using Holder class to save the Tag information of convertView.
and also giving a unique ID to viewPager.I basically intend to show Images in ViewPager but to test the code I am working with TextViews.
public class ListViewAdapter extends ArrayAdapter<ParsedItems> {
LinearLayout mainLinnerLayout;
ViewPagerAdapter pagerAdapter;
Context context;
ArrayList<ParsedItems> mObject;
ViewPagerAdapter adapter;
private ProgressDialog progressDialog;
public ListViewAdapter(Context context,int resource, ArrayList<ParsedItems> objects) {
super(context,resource,objects);
this.context = context;
this.mObject = objects;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
Holder holder=null;
ParsedItems items = mObject.get(position);
String template = items.getTemplate();
ParsedItemsImage mInnerItem;
ArrayList<ParsedItemsImage> mInnerItems = items.getItems();
LinearLayout innerLinearLayout=null;
if((Holder)convertView.getTag() == null){
LayoutInflater inflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = inflater.inflate(R.layout.row_layout_template3, parent,false);
ViewPager viewPager = (ViewPager)convertView.findViewById(R.id.pager);
holder = new Holder();
holder.viewPager = viewPager;
holder.viewPager.setId(NotificationID.getID());
holder.textView = (TextView)convertView.findViewById(R.id.template3_textView);
convertView.setTag(holder);}
else
{
holder = (Holder)convertView.getTag();
}
holder.textView.setText("oyi!");
pagerAdapter = new ViewPagerAdapter(mInnerItems,context,convertView);
holder.viewPager.setAdapter(pagerAdapter);
return convertView;
}
class Holder
{
TextView textView;
ViewPager viewPager;
}
}
ViewPagerAdapter class:
public class ViewPagerAdapter extends PagerAdapter {
ArrayList<ParsedItemsImage> mInnerItems;
Context context;
private final WeakReference<View> ref;
public ViewPagerAdapter(ArrayList<ParsedItemsImage> items,Context context, View view)
{
mInnerItems = new ArrayList<ParsedItemsImage>(items);
this.context = context;
ref = new WeakReference<View>(view);
}
#Override
public int getCount() {
//return mInnerItems.size();
return 6;
}
#Override
public boolean isViewFromObject(View view, Object o) {
return false;
}
#Override
public Object instantiateItem(ViewGroup container, int position) {
View collection;
ParsedItemsImage mParsedItemsImage = mInnerItems.get(position);
String url=mParsedItemsImage.getImage();
LayoutInflater inflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
collection = inflater.inflate(R.layout.template3_imageview,container,false);
TextView textView = (TextView)collection.findViewById(R.id.text_temp3);
ViewPager vp = (ViewPager)container;
textView.setText("test");
vp.addView(collection);
return textView;
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView((TextView) object);
}
}
Template3_imageview.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="200dp">
<TextView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/text_temp3"/>
<ImageView
android:layout_width="match_parent"
android:layout_height="100dp"
android:id="#+id/imageView_template3"/>
</LinearLayout>
Output:
SO the output shows the textview added in the ArrayAdapter's getView() method :
holder.textView.setText("oyi!");
but doesn't show the one in the ViewPager Adapter:
textView.setText("test");
Please help.
P.S.: I intend to add images finally but i was testing if textviews are getting added in pager or not.So you will see some extra code in the post.

The error was in isViewFromObject() method. I changed this
#Override
public boolean isViewFromObject(View view, Object o) {
return false;
}
to
#Override
public boolean isViewFromObject(View view, Object o) {
return view == o;
}
and it worked!

Adding A button and a TextView for each Line of a ListView

I am currently working on a very basic android application and have encountered an obstacle I cannot solve on my own.
In my application I want to have a start screen with a ListView. In each Line of this ListView there should be a Button and a TextView. I want to have approximately 5 Lines. When you click on each of the Button you should be able to get to different Activities. How do I do that? I read something about adapters but I am still not sure how to build this.
Here's my xml code for the TextView and the Button:
<RelativeLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/textView"
android:id="#+id/rl01">
<TextView
android:layout_width= "wrap_content"
android:layout_height="50dp"
android:id="#+id/text01"
android:text="hello"
android:textSize="24dp"
android:textColor="#color/abc_search_url_text_normal"
android:paddingRight="#dimen/activity_horizontal_margin"
/>
<Button
android:layout_width="wrap_content"
android:layout_height="50dp"
android:layout_toRightOf="#id/text01"
android:text="Press Me!"
/>
</RelativeLayout>

The xml layout you have posted, will be used as each listview item.
Step 1:
Create a class which extends BaseAdapter;
public class CustomAdapter extends BaseAdapter
{
Context con;
String[] data;
public CustomAdapter (Context context, String[] data)
{
this.con = context;
this.data = data;
}
#Override
public int getCount() {
return data.length;
}
#Override
public Object getItem(int position) {
return data[position];
}
#Override
public long getItemId(int position) {
return 0;
}
//this method will be called for every item of your listview
#Override
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = (LayoutInflater) con.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView= inflater.inflate(R.layout.customview, parent, false);
TextView text = (TextView) view.findViewById(your text view id); //recognize your view like this
text.setText(data[position]);
return convertView;
}
}
Step 2:
In your activity, recognize your listview:
yourListViewReference = (ListView) findViewById(R.id.your_list_view_id);
And initialize String array:
String[] data = {"item 1", "item2", "item3"}; //how many items you want
And then create instance of custom adapter you created, and set it to listview:
CustomAdapter ad = new CustomAdapter(this, data);
yourListViewReference.setAdapter(ad);
And sorry for my bad english. I am actually working on it.

This article from Vogella is really useful for what you want to do.
Basically, you'll create an Adapter that extends the BaseAdapter class as follows:
public class Adapter extends BaseAdapter {
private List<Item> mItems;
private Context mContext;
public EventAdapter(Context context, List<Event> items) {
mContext = context;
mItems = items;
}
public View getView(int position, View convertView, ViewGroup parent) {
// This recycles your view and prevents constant inflation, which can really hit your performance.
View rowView = convertView;
if (rowView == null) {
ViewHolder viewHolder = new ViewHolder();
rowView = inflater.inflate(R.layout.yourLayout, parent, false);
viewHolder.text = (TextView) rowView.findViewById(R.id.yourTextViewId);
viewHolder.button = (Button) rowView.findViewById(R.id.yourButtonId);
rowView.setTag(viewHolder);
}
ViewHolder holder = (ViewHolder) rowView.getTag();
// Get the correct item by position
Item item = item.get(position);
// Update the row layout with your item data
holder.text.setText(item.text);
holder.button.setButton(item.button);
// Return your row view
return rowView;
}
#Override
public int getCount() {
return mItems.size();
}
#Override
public Object getItem(int position) {
}
#Override
public long getItemId(int position) {
}
static class ViewHolder {
public TextView text;
public Button button;
}
Afterwards you just need to set this adapter to your ListView or RecyclerView by doing
listView.setAdapter(new Adapter(this, items));

I would write a simple example:
You dont need a button in listview row, just implement onItemClick();
main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="match_parent"
android:orientation="vertical"
>
<ListView
android:id="#+id/custom_list"
android:longClickable="true"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
</LinearLayout>
list_row.xml
<RelativeLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/textView"
android:id="#+id/rl01">
<TextView
android:layout_width= "wrap_content"
android:layout_height="50dp"
android:id="#+id/text01"
android:text="hello"
android:textSize="24dp"
android:textColor="#color/abc_search_url_text_normal"
android:paddingRight="#dimen/activity_horizontal_margin"
/>
MainActivity.java
oncreate()
{
....
lv1 = (ListView) result.findViewById(R.id.custom_list);
String[] listdata = {"txt1", "txt2", "txt3", "txt4", "txt5"};
ListAdapter listAdapt = new ListAdapter(this, listdata );
lv1.setAdapter(listAdapt);
lv1.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> a, View v, int position, long id) {
//do ur work here when list row selected
}
});
..
}
ListAdapter.java
public class ListAdapter extends BaseAdapter {
String[] listData;
private LayoutInflater layoutInflater;
public CustomListAdapter(Context aContext, String[] listData) {
this.listData = listData;
layoutInflater = LayoutInflater.from(aContext);
}
#Override
public int getCount() {
return listData.size();
}
#Override
public Object getItem(int position) {
return listData.get(position);
}
#Override
public long getItemId(int position) {
return position;
}
public View getView(int position, View convertView, ViewGroup parent) {
if (convertView == null) {
convertView = layoutInflater.inflate(R.layout.list_row, null);
TextView tv1 = (TextView)convertView.findViewById(R.id.text01);
tv1.setText(listData.[position]);
return convertView;
}

Why is my ListView empty after calling setListAdapter inside ListFragment?

I am trying to populate a ListView with data from a web service using Retrofit, but my ListView is somehow always empty. I am getting the data from the web service fine, it just isn't getting into the ListView. setListAdapter() doesn't seem to be doing anything because the listview's count is 0 after I call it. Why is my ListView empty? Here is some of my code:
public class PopularFragment extends ListFragment{
private final String NAME = "Popular";
RestClient restClient;
#Override
public void onActivityCreated(Bundle savedInstanceState)
{
super.onActivityCreated(savedInstanceState);
restClient = RestClientService.getService();
restClient.getApps(new Callback<List<App>>() {
#Override
public void success(List<App> apps, Response response) {
Log.v("test", apps.toString());
setListAdapter(new AppListAdapter(getActivity(), apps));
Log.v("test", Integer.toString(getListAdapter().getCount()));
Log.v("test", Integer.toString(getListView().getCount()));
}
#Override
public void failure(RetrofitError retrofitError) {
Log.v("test", "failure");
}
});
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_browse_apps, container, false);
return view;
}
The two log methods Log.v("test", Integer.toString(getListAdapter().getCount())); and
Log.v("test", Integer.toString(getListView().getCount())); both return 0.
Here is my custom adapter:
public class AppListAdapter extends ArrayAdapter<App>
{
private final Context context;
private List<App> apps;
public AppListAdapter(Context context, List<App> apps)
{
super(context, R.layout.app_list_item);
this.context = context;
this.apps = apps;
}
#Override
public View getView(int position, View convertView, ViewGroup parent)
{
View view = convertView;
LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
if (convertView == null) {
view = inflater.inflate(R.layout.app_list_item, parent, false);
}
App app = this.apps.get(position);
TextView appName = (TextView) view.findViewById(R.id.appName);
appName.setText("TEST");
return view;
}
}
app_list_item.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent" android:layout_height="match_parent"
android:orientation="vertical" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="App Name"
android:id="#+id/appName" />
fragment_browse_apps.xml:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.android.devon.appfrenzy.BrowseAppsActivity$PlaceholderFragment">
<TextView
android:id="#+id/section_label"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="HELLO" />
<ListView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#android:id/list"
android:layout_centerHorizontal="true" />

You should call the 3 variable constructor for the ListAdapter:
public AppListAdapter(Context context, List<App> apps)
{
super(context, R.layout.app_list_item,apps);
this.context = context;
}
Then you don't actually need to store apps off, it can be retrieved using getItem
#Override
public View getView(int position, View convertView, ViewGroup parent)
{
View view = convertView;
LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
if (convertView == null) {
view = inflater.inflate(R.layout.app_list_item, parent, false);
}
App app = getItem(position);
TextView appName = (TextView) view.findViewById(R.id.appName);
appName.setText("TEST");
return view;
}