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How to set layout with XML in View for BaseAdapter getView() method

The following Java code (from https://www.intertech.com/Blog/android-adapters-adapterviews/) is from getView(), a method implementation from a Android Adapter class, and it builds a View in Java to populate items on a List. I get how it works, but the same page says it can be built using an XML file, which makes sense to me, but I'm unable to find any examples. I understand how to use XML resource files to set Activity layout using setContentView(). But how would I invoke an XML resource file to build the View in the getView() method?
#Override
public View getView(int position, View convertView, ViewGroup parent) {
if (convertView == null) {
Context context = parent.getContext();
LinearLayout view = new LinearLayout(context);
view.setOrientation(LinearLayout.HORIZONTAL);
view.addView(new CheckBox(context));
TextView nameTextView = new TextView(context);
nameTextView.setText(courses.get(position).getName());
nameTextView.setPadding(0, 0, 10, 0);
view.addView(nameTextView);
TextView parTextView = new TextView(context);
parTextView.setText(Integer.toString(courses.get(position).getPar()));
view.addView(parTextView);
return view;
}
return convertView;
}

like this
item_test.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="wrap_content"
android:orientation="vertical">
<TextView
android:id="#+id/name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
tools:text="name" />
</LinearLayout>
adapter
#Override
public View getView(int position, View convertView, ViewGroup parent) {
Holder holder; // use holder
if (convertView == null) {
convertView = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_test, parent, false);
holder = new Holder(convertView);
convertView.setTag(holder);
} else {
holder = (Holder) convertView.getTag();
}
holder.name.setText("name");
return convertView;
}
public class Holder {
private TextView name;
public Holder(View view) {
name = view.findViewById(R.id.name);
}
}

Android TextView SetText null object reference error

I am new to android and I am getting a
Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
error on my app. I have read other questions on here like this one - java.lang.NullPointerException - setText on null object reference but I still get the same issue. My format is a little bit different as this is done in a Fragment and what I am doing is having a Custom Adapter from a listview. Here is my code
fragment_song_genre.xml
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:bind="http://schemas.android.com/tools">
<data class="SongGenreBinding">
<variable
name="handler"
type="com.mgrmobi.joox.fragments.FilterSongGenreFragment" />
</data>
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#000">
<RelativeLayout
android:id="#+id/toprow"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="24dp">
<ImageButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true"
android:layout_marginLeft="16dp"
android:background="#null"
android:onClick="#{ handler.onCloseClicked }"
android:src="#drawable/search_close" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true"
android:layout_marginLeft="80dp"
android:text="Genre"
android:textColor="#fff"
android:textSize="20sp" />
<TextView
android:onClick="#{ handler.reset }"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_centerVertical="true"
android:layout_marginRight="15dp"
android:text="#string/reset"
android:textAllCaps="true"
android:textColor="#fff"
android:textSize="12sp" />
</RelativeLayout>
<ListView
android:id="#+id/list"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="#id/toprow"
android:layout_marginTop="24dp"></ListView>
</RelativeLayout>
That is the main page and it has a Listview in the Bottom and here is the fragment that calls that xml layout
public class FilterSongGenreFragment extends BaseFragment {
private SongGenreBinding binding;
private ArrayList<String> genres;
String[] names= {"Johm","Paul","Mike"};
#Override
public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {
super.onCreateContextMenu(menu, v, menuInfo);
}
private static final String GENRES_KEY = "genres";
public static FilterSongGenreFragment newInstance(ArrayList<String> genres) {
Bundle args = new Bundle();
args.putStringArrayList(GENRES_KEY, genres);
FilterSongGenreFragment fragment = new FilterSongGenreFragment();
fragment.setArguments(args);
return fragment;
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
binding = DataBindingUtil.inflate(inflater, R.layout.fragment_song_genre, container, false);
binding.setHandler(this);
genres = getArguments().getStringArrayList(GENRES_KEY);
initList();
return binding.getRoot();
}
private void initList() {
// ArrayAdapter adapter = new ArrayAdapter(getActivity(), R.layout.genre_list_text, android.R.id.text1, genres);
FilterSongsAdapter filterSongsAdapter= new FilterSongsAdapter(getActivity(),names);
binding.list.setAdapter(filterSongsAdapter);
binding.list.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> adapterView, View view,int position, long l) {
((SongFilterListener) getActivity()).onGenreSelected(genres.get(position));
/*
textView = (ImageView) view.findViewById(R.id.selected_genre);
textView.setVisibility(View.VISIBLE);
*/
// close();
}
});
}
private void close() {
getActivity().getFragmentManager().beginTransaction().remove(this).commit();
}
public void onCloseClicked(View view) {
close();
}
public void reset(View view) {
((SongFilterListener) getActivity()).onResetFilters();
close();
}
}
Here is the xml for the listview custom style genre_list_text.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<TextView
android:id="#android:id/text1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="center_vertical|left"
android:text="Genre"
android:paddingBottom="16dp"
android:paddingLeft="4dp"
android:paddingTop="16dp"
android:textColor="#fff"
android:textSize="16sp" />
<ImageView
android:id="#+id/selected_genre"
android:layout_height="24dp"
android:layout_width="24dp"
android:visibility="invisible"
android:src="#drawable/check_circle"
android:layout_marginStart="140dp"
android:layout_centerVertical="true" />
</RelativeLayout>
and here is my adapter and as stated before the error happens in the SetText area
public class FilterSongsAdapter extends ArrayAdapter<String> {
private Context c;
String[] names= {};
LayoutInflater inflater;
public FilterSongsAdapter(Context context,String[] names) {
super(context,R.layout.genre_list_text,names);
this.c=context;
this.names=names;
}
public static class ViewHolder {
TextView text1;
}
#Override
public View getView(int position,View convertView,ViewGroup parent) {
ViewHolder holder;
if(convertView==null){
holder = new ViewHolder();
inflater = (LayoutInflater) c.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = inflater.from(c).inflate(R.layout.genre_list_text, null);
// Initialize
holder.text1=(TextView) convertView.findViewById(R.id.text1);
convertView.setTag(holder);
}else {
holder = (ViewHolder) convertView.getTag();
}
holder.text1.setText(names[position]);
return convertView;
}
}
The SetText inside the GetView is throwing the exception every time, that TextView should have 3 objects names from the Names String Array which I have seen that it has. Based on the error I know that i'm setting the SetText before the FindByID method locates the TextView but I have moved things around and nothing works. Any help would be great . I also been following this tutorial for reference https://www.youtube.com/watch?v=99C_UpLcBRk . I do not know if maybe with a Fragment things are different.

in your layout you have given default id to TextView android:id="#android:id/text1".
and in JAVA file you are giving R.id.text1
make changes in xml or java.
ether change in xml from android:id="#android:id/text1" to android:id="#+id/text1"
or in java android.R.id.text1

#Override
public View getView(int position,View convertView,ViewGroup parent) {
ViewHolder holder = new ViewHolder(); //because error says null object reference, it means object of TextView `text1` is not found.
inflater = (LayoutInflater) c.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
if(convertView==null){
convertView = inflater.inflate(R.layout.genre_list_text, null);
holder.text1=(TextView) convertView.findViewById(R.id.text1);
holder.text1.setText(names[position]);
convertView.setTag(holder);
}else {
holder = (ViewHolder) convertView.getTag();
}
return convertView;
}
And from your provided XML code, I can see you did not provided a proper id for TextView. Change in XML from android:id="#android:id/text1" to android:id="#+id/text1".

In your genre_list_text.xml change android:id="#android:id/text1" to android:id="#+id/text1"
and in your getView Method
#Override
public View getView(final int position, View convertView, ViewGroup parent) {
ViewHolder holder;
View view = convertView;
if (view == null) {
LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
view = inflater.inflate(R.layout.genre_list_text, parent, false);
viewHolder = new ViewHolder();
holder.text1=(TextView) view.findViewById(R.id.text1);
view.setTag(viewHolder);
} else {
viewHolder = (ViewHolder) view.getTag();
}
holder.text1.setText(names[position]);
return view;
}

Listview sometimes null when I use gettag

I have a problem with my view in Android. I use a GridView with items inside it. Each item does have a name, button,description and icon. But each item also has a listview. When I click on the button I want to show the listview that is linked to that button.
On startup it works, but when I scroll up and down a few times my listview either doesn't show or it shows the wrong listview.
I have read alot of other questions and articles, but I cant find the thing I am doing wrong.
Also tried something like this but that still gives the same result
if (convertView == null){
holder = new new ListHolder();
convertView.setTag(holder);
}
else {
holder = (ListHolder) convertView.getTag();
}
The getView
#Override
public View getView(int position, View convertView, ViewGroup parent) {
View row = convertView;
ListHolder holder;
HarmonicaItem harmonicaItem = ((MainActivity) context).getHarmonicaItems().get(position);
if (row == null) {
LayoutInflater inflater = ((Activity) context).getLayoutInflater();
row = inflater.inflate(layoutResourceId, parent, false);
}
holder = new ListHolder();
holder.logo = (ImageView) row.findViewById(R.id.logo);
holder.line = (TextView) row.findViewById(R.id.line);
holder.button = (Button) row.findViewById(R.id.button);
holder.listView = (ListView) row.findViewById(R.id.subHarmonica);
holder.logo.setImageResource(harmonicaItem.logo);
holder.button.setText(harmonicaItem.title);
holder.button.setOnClickListener(onClickListener);
harmonicaItem.listView = holder.listView;
harmonicaItem.button = holder.button;
holder.listView.setTag(harmonicaItem);
holder.button.setTag(harmonicaItem);
row.setTag(holder);
return row;
}
The Model class
static class ListHolder {
ImageView logo;
TextView line;
Button button;
ListView listView;
}
How I retrieve the item
#Override
public void onClick(View v) {
HarmonicaItem item = (HarmonicaItem) v.getTag();
}
layout of item inside gridview:
<RelativeLayout
android:id="#+id/buttonLayout"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<Button
android:id="#+id/button"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#android:color/transparent"
android:gravity="center_vertical|left"
android:paddingLeft="115dp"
android:paddingRight="10dp"
android:text="loop"
android:textColor="#android:color/black"
android:textStyle="bold"/>
<ImageView
android:id="#+id/logo"
android:layout_width="35dp"
android:layout_height="35dp"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true"
android:layout_marginLeft="10dp" />
<TextView
android:id="#+id/line"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="#+id/button"
android:layout_alignBottom="#+id/button"
android:layout_centerVertical="true"
android:layout_marginLeft="10dp"
android:layout_toRightOf="#+id/logo"
android:text="00:00"
android:textAppearance="?android:attr/textAppearanceMedium"
android:textColor="#android:color/black"
android:textStyle="bold"/>
</RelativeLayout>
<ListView
android:id="#+id/subHarmonica"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="#id/buttonLayout"
android:visibility="gone"/>
So a summary of my problem:
item.listView is sometimes null and sometimes the wrong listview.
My goal is to fill the listview and make it visible when you click the button.
What am I doing wrong?
Edit
Apparently I made a mistake in other code. When the listviews went back to gone I saved the listview. When I wanted it to show again it sometimes took the wrong list. So there is actually nothing wrong with the adapter.

Try this. Some issue in your code
1. You miss the else part
2.need to Set tag inside if condition
#Override
public View getView(int position, View convertView, ViewGroup parent) {
View row = convertView;
ListHolder holder;
HarmonicaItem harmonicaItem = ((MainActivity) context).getHarmonicaItems().get(position);
if (row == null) {
LayoutInflater inflater = ((Activity) context).getLayoutInflater();
row = inflater.inflate(layoutResourceId, parent, false);
holder = new ListHolder();
holder.logo = (ImageView) row.findViewById(R.id.logo);
holder.line = (TextView) row.findViewById(R.id.line);
holder.button = (Button) row.findViewById(R.id.button);
holder.listView = (ListView) row.findViewById(R.id.subHarmonica);
holder.listView.setTag(harmonicaItem);
holder.button.setTag(harmonicaItem);
row.setTag(holder);
}else{
holder = (ListHolder)row.getTag();
}
holder.logo.setImageResource(harmonicaItem.logo);
holder.button.setText(harmonicaItem.title);
holder.button.setOnClickListener(onClickListener);
return row;
}
Edit:
I removed 2 lines of code in that is
armonicaItem.listView = holder.listView;
harmonicaItem.button = holder.button;
I think this is not needed. Try without this.

Plz update your getView method
#Override
public View getView(int position, View convertView, ViewGroup parent) {
if (convertView == null)
{
holder = new ViewHolder();
LayoutInflater inflater = LayoutInflater.from(parent.getContext());
convertView = inflater.inflate(R.layout.list_row, null);
holder.logo = (ImageView) row.findViewById(R.id.logo);
holder.line = (TextView) row.findViewById(R.id.line);
holder.button = (Button) row.findViewById(R.id.button);
holder.listView = (ListView) holder.findViewById(R.id.subHarmonica);
holder.listView.setTag(harmonicaItem);
holder.button.setTag(harmonicaItem);
holder.setTag(holder);
}
else {
holder = (ListHolder)row.getTag();
}
holder.logo.setImageResource(harmonicaItem.logo);
holder.button.setText(harmonicaItem.title);
holder.button.setOnClickListener(onClickListener);
return convertView;
}

onclick Listener for custom listview

I am developing an android application with a custom list view ( with a single image and two text views)
The class mainactivity has ....
public class MainActivity extends ActionBarActivity {
String[] memetitles;
String[] memedesc;
ListView list;
int[] images = {R.drawable.angry_icon,R.drawable.happy_icon,R.drawable.kid_icon,R.drawable.scare_icon,R.drawable.warn_icon};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Resources res = getResources();
memetitles = res.getStringArray(R.array.titles);
memedesc = res.getStringArray(R.array.notneed);
list = (ListView) findViewById(R.id.listView1);
Itarray adapter = new Itarray(this,memetitles,memedesc,images);
list.setAdapter(adapter);
setTitle("Tamil Memer");
}
The class for combining two layouts into a single list view has
class Itarray extends ArrayAdapter<String>{
Context context;
int[] image;
String[] tit1;
String[] tit2;
Itarray(Context c , String[] titles ,String[] notneed, int imgs[])
{
super(c , R.layout.single_row,titles);
this.context = c;
this.image = imgs;
this.tit1 = titles;
this.tit2 = notneed;
}
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
View row = convertView;
if(row == null)
{
LayoutInflater inf = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
row = inf.inflate(R.layout.single_row , parent , false);
}
ImageView myImage = (ImageView) row.findViewById(R.id.imageView1);
TextView tit = (TextView) row.findViewById(R.id.textView1);
TextView des = (TextView) row.findViewById(R.id.textView2);
myImage.setImageResource(image[position]);
tit.setText(tit1[position]);
des.setText(tit2[position]);
return row;
}
}
The two layout files :
(the one with the image and the textviews)
<RelativeLayout 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"
android:gravity="top"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.itassistors.tmg.MainActivity" >
<TextView
android:id="#+id/textView1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true"
android:layout_toEndOf="#+id/imageView1"
android:layout_toRightOf="#+id/imageView1"
android:text="#string/simple"
android:textAppearance="?android:attr/textAppearanceLarge" />
<TextView
android:id="#+id/textView2"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignBottom="#+id/imageView1"
android:layout_alignLeft="#+id/textView1"
android:layout_alignStart="#+id/textView1"
android:text="#string/simple"
android:textAppearance="?android:attr/textAppearanceSmall" />
<ImageView
android:id="#+id/imageView1"
android:layout_width="50dp"
android:layout_height="50dp"
android:layout_alignParentLeft="true"
android:layout_alignTop="#+id/textView1"
android:src="#drawable/happy_icon" />
(the one with the listview)
<RelativeLayout 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"
android:gravity="center_vertical"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.itassistors.tmg.MainActivity" >
<ListView
android:id="#+id/listView1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true" >
</ListView>
I want to know how and where to place the onClickListener() for this custom list view
Thanks in advance

You have two options:
1) Set the click listener in your activity:
list.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view,int position, long id) {
// Do your stuff here
}
});
2) Set the click listener in your adapter:
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
View row = convertView;
if(row == null)
{
LayoutInflater inf = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
row = inf.inflate(R.layout.single_row , parent , false);
}
ImageView myImage = (ImageView) row.findViewById(R.id.imageView1);
TextView tit = (TextView) row.findViewById(R.id.textView1);
TextView des = (TextView) row.findViewById(R.id.textView2);
myImage.setImageResource(image[position]);
tit.setText(tit1[position]);
des.setText(tit2[position]);
row.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// Do your stuff here
}
});
return row;
}

If you are doing it in adapter you will to follow this code:
#Override
public View getView(final int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
ViewHolderItem holder;
if (convertView == null) {
convertView = inflater.inflate(R.layout.your_list_item, null);
View row = convertView;
holder = new ViewHolderItem();
convertView.setTag(holder);
row.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Log.v(LOG_TAG, "ROW PRESSED");
context.startActivity(new Intent(context, YourAction.class));
}
});
} else {
holder = (ViewHolderItem) convertView.getTag();
}
return convertView;
}

change order of object in row of listview programmaticaly

currently i have:
<TextView
android:id="#+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="15:22:33 \nApr 13 1999"
android:textColor="#FFFFFFFF"
android:textAppearance="?android:attr/textAppearanceSmall" />
<TextView
android:id="#+id/comment"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_margin="5dip"
android:background="#drawable/incoming_message_buble"
android:paddingLeft="10dip"
android:text="Hello bubbles!"
android:textColor="#android:color/primary_text_light" />
and it work fine.
here is adapter code:
public View getView(int position, View convertView, ViewGroup parent) {
View row = convertView;
if (row == null) {
LayoutInflater inflater = (LayoutInflater) this.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
row = inflater.inflate(R.layout.activity_sms_row_layout, parent, false);
}
wrapper = (LinearLayout) row.findViewById(R.id.wrapper);
OneComment coment = getItem(position);
countryName = (TextView) row.findViewById(R.id.comment);
countryName.setText(coment.comment);
countryName.setBackgroundResource(coment.left ? R.drawable.incoming_message_buble : R.drawable.outgoing_message_buble);
wrapper.setGravity(coment.left ? Gravity.LEFT : Gravity.RIGHT);
return row;
}
i have to change order, for gravity left, i need shown textview comment first, and textView1 second
for gravity right, keep xml setting.
please advise.

I suggest using multiple layouts rather than constantly reorganizing each row's layout. Override these two methods:
#Override
public int getItemViewType(int position) {
return getItem(position).left ? 0 : 1;
}
#Override
public int getViewTypeCount() {
return 2;
}
And modify your getView():
#Override
public View getView(int position, View convertView, ViewGroup parent) {
if(getItemViewType == 0) {
// Use the left layout
} else {
// Use the right layout
}
}