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;
}
}
Related
I tried to set up a custom ListView as a table to display Product Details. As you see in my Code I use a custom adapter and a additional xml file to populate the ListView. My problem is that the ListView ist empty. There are no items displayed and I do not see my mistake. Can you help me?
Fragment:
public class ProductDetail1Fragment extends Fragment {
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_product_detail1,container,false);
HashMap<String,String> mapProduct = new HashMap<String,String>();
for(int i=0;i<10;i++) {
mapProduct.put("Key" + i, "Value" + i);
}
ListView listView=(ListView) view.findViewById(R.id.productListview);
ProductDetailAdapter adapter = new ProductDetailAdapter(getActivity(),mapProduct);
listView.setAdapter(adapter);
return view;
}
Adapter:
public class ProductDetailAdapter extends BaseAdapter {
private HashMap<String,String> list;
private Context context;
public ProductDetailAdapter(Context c, HashMap<String,String> list){
super();
this.context = c;
this.list=list;
}
#Override
public View getView(int position, View convertView, ViewGroup viewGroup) {
LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
if(convertView == null){
convertView=inflater.inflate(R.layout.product_detail_data_row,null);
}
TextView textViewKey = (TextView)convertView.findViewById(R.id.productDataKey);
TextView textViewValue = (TextView)convertView.findViewById(R.id.productDataValue);
textViewKey.setText("tst");
textViewValue.setText("ddfadfs");
return convertView;
}
}
Fragment.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.parker.tfdeapp.ProductDetail2Fragment">
<ListView
android:id="#+id/productListview"
android:layout_width="match_parent"
android:layout_height="wrap_content">
</ListView>
</LinearLayout>
Listview_row.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/productDataKey"
android:layout_height="wrap_content"
android:layout_width="0dp"
android:layout_weight="1"
android:textStyle="bold" />
<TextView
android:id="#+id/productDataValue"
android:layout_height="wrap_content"
android:layout_width="0dp"
android:layout_weight="1" />
</LinearLayout>
Add getCount method in your adapter
#Override
public int getCount() {
return list.size();
}
Add this Override methods in your adapter class
#Override
public int getCount() {
return list.size();
}
#Override
public ListData getItem(int position) {
return list.get(position);
}
#Override
public long getItemId(int position) {
return position;
}
Missing class implementations of BaseAdapter.
See the documentation
#Override
public int getCount() {
return list.size();
}
#Override
public ListData getItem(int position) {
return list.get(position);
}
#Override
public long getItemId(int position) {
return position;
}
Implementing getCount() only makes items visible. Because it provides
item counts.
1) Need to change ListView to match parent height (its bad performance):
<ListView
android:id="#+id/productListview"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
2) Just to override missing functions in your BaseAdapte:
#Override
public int getCount() {
return mList.size();
}
#Override
public ListData getItem(int index) {
return mList.get(index);
}
#Override
public long getItemId(int index) {
return index;
}
3) Use ViewHolder... its very good pattern
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!
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;
}
I already saw a bunch of questions but i didn't found an solution! What im doing wrong? Why getView is never called?!
Here`s my adapter:
public class ConteudoAdapter<T extends IProgramacao> extends BaseAdapter {
private Context context;
private List<T> list;
private int resourceId;
public ConteudoAdapter(Context context, int resourceId, List<T> list){
this.context = context;
this.list = list;
this.resourceId = resourceId;
}
#Override
public int getCount() {
Log.v("test", "Returning count " + (this.list.size() != 0 ? this.list.size() : 0));
return list.size();
}
#Override
public Object getItem(int position) {
return list.get(position);
}
#Override
public long getItemId(int position) {
return position;
}
#Override
public View getView(int position, View view, ViewGroup parent) {
View row = view;
ViewHolder holder = null;
T entidade = list.get(position);
if(row == null)
{
LayoutInflater inflater = ((Activity) context).getLayoutInflater();
row = inflater.inflate(resourceId, parent, false);
holder = new ViewHolder();
holder.tvTitle = (TextView) row.findViewById(R.id.tvTitle);
holder.tvTitle.setText(entidade.getTitulo());
holder.tvConteudo = (TextView) row.findViewById(R.id.tvConteudo);
holder.tvConteudo.setText(entidade.getChamada());
row.setTag(holder);
}
// holder.ivImg = (ImageView) layout.findViewById(R.id.nivImg);
// holder.ivImg.setImageResource(entidade.);
// IMAGE VIEW
// holder.ivImg.setVisibility(View.VISIBLE);
// il.get(list.get(position).getUrlImage(), il.getImageListener(holder.ivImg, R.drawable.load, R.drawable.error));
//tvTitle.setText(entidade.getTitulo());
return view;
}
public static class ViewHolder{
//public NetworkImageView nivImg;
//public ImageView ivImg;
public TextView tvTitle;
public TextView tvConteudo;
}
}
Here`s how i call my adapter (inside an asynctask because im getting values from web (JSON):
public class CategoriaEventoFragment extends SherlockFragment {
private View rootView;
private EventoBO evento;
private ListView lv;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// TODO Auto-generated method stub
rootView = (View) inflater.inflate(R.layout.categoria, container, false);
CarregaDadosCategoriaEventoCaller carregaDadosCategoriaEventoCaller = new CarregaDadosCategoriaEventoCaller();
carregaDadosCategoriaEventoCaller.execute((Void[]) null);
return super.onCreateView(inflater, container, savedInstanceState);
}
public class CarregaDadosCategoriaEventoCaller extends AsyncTask<Void, Void, Void> {
#Override
protected Void doInBackground(Void... params) {
// TODO Auto-generated method stub
evento = new EventoBO("http://urlhere");
evento.popularListaImagemChamada("http://urlhere");
return null;
}
#Override
protected void onPostExecute(Void result) {
// TODO Auto-generated method stub
lv = (ListView) rootView.findViewById(R.id.listViewCategoria);
lv.setAdapter(new ConteudoAdapter<Evento>(rootView.getContext(), R.layout.item, evento.getLista()));
}
}
}
}
XML FILES:
item.xml
<?xml version="1.0" encoding="utf-8"?>
<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="fill_parent"
android:background="#drawable/home_bg_branco"
android:orientation="horizontal" >
<TextView
android:id="#+id/tvTitle"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
<TextView
android:id="#+id/tvConteudo"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
</LinearLayout>
categoria.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical" >
<ListView
android:id="#+id/listViewCategoria"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#drawable/home_bg_branco" >
</ListView>
</LinearLayout>
My LogCat Returns this for my verbose test:
09-02 17:13:27.322: V/test(24961): Returning count 5
09-02 17:13:27.322: V/test(24961): Returning count 5
Thanks in advance!!!
In onCreateView() you should be returning the rootView instead of the super.
I'd like to customize some settings (color, margin) for some items on a listview in a listactivity after or before setting the adapter. How can I do that? Is there any function that can I override?
Thank you.
you can use an own listadapter.. http://www.vogella.com/articles/AndroidListView/article.html
This is how you can do to customize item of your list:
Layout of your list:
<?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">
<ListView
android:id="#android:id/list"
android:layout_width="match_parent"
android:layout_height="match_parent"
/>
</LinearLayout>
Layout of each 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">
<TextView
android:id="#+id/text"
android:layout_height="wrap_content"
android:layout_width="wrap_content"
/>
</LinearLayout>
And finaly your activity:
public class MyActivity extends ListActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.list_activitty);
final List<String> list = new ArrayList<String>();
list.add("test");
list.add("test");
list.add("test");
final CustomAdapter adapter = new CustomAdapter(this, list);
final ListView listView = getListView();
listView.setAdapter(adapter);
}
public class CustomAdapter extends BaseAdapter {
private Context mContext;
private List<String> mList;
public CustomAdapter(Context context, List<String> list) {
mContext = context;
mList = list;
}
#Override
public int getCount() {
return mList.size();
}
#Override
public String getItem(int position) {
return mList.get(position);
}
#Override
public long getItemId(int position) {
return 0;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
final Holder holder;
if (convertView == null) {
// if it is the first time you create the row
// you get the layout of each row here
convertView = LayoutInflater.from(mContext).inflate(R.layout.item_list, null);
// you keep your layout in a holder
holder = new Holder();
holder.mText = (TextView) convertView.findViewById(R.id.text);
convertView.setTag(holder);
} else {
// if the row has already been created, you get it from the holder
holder = (Holder) convertView.getTag();
}
// you do what you want with the content
holder.mText.setText(getItem(position));
holder.mText.setTextColor(Color.BLUE);
return convertView;
}
private class Holder {
public TextView mText;
}
}
}