I am reposting this question as one person marked my previous queston duplicate even without reading the question.
I am creating a adapter of ListView, for loading my custom layout as list members.
The layout contains
3 RelativeLayout
and each of the latter contains a TextView
and a Button.
In the ListView there will be at max 2 rows, in short at max 6 RelativeLayout. As the need is recursive I have used array of TextView,RelativeLayout,Button. For assigning Id through findViewById(), I am using int array which contains all ids defined in layout. Now after I assign the widgets their Id, when I am invoking any method it is giving null pointer exception, which mean that the widget is not assigned Id but I cannot understand why it is not assigned.
One more point that the ListView is populated within an RecyclerView.Adapter. The whole scene is like this:
i) I have a activity with Tabs & Pager. Hence it uses fragments for each tab. Here I am talking about first tab only.
ii) In the fragment I have a RecyclerView which will load cards.
iii) The card has many widget, one of them is ListView. So In RecyclerView.Adapter I will call the ArrayAdapter for this List
My code is as follow:
1) ArrayAdapter (which shows error)
public class ElectionOptionAdapter extends ArrayAdapter<String> {
Activity context;
int noOption;
String[] options, description;
TextView[] optionText, optionDescription;
RelativeLayout[] optionImage;
Button[] optionButton;
int[]
text = new int[]{R.id.ERowOption1,R.id.ERowOption2,R.id.ERowOption3},
des = new int[]{R.id.ERowOption1des,R.id.ERowOption2des,R.id.ERowOption3des},
img = new int[]{R.id.ERowOption1Img,R.id.ERowOption2Img,R.id.ERowOption3Img},
but = new int[]{R.id.ERowOption1button,R.id.ERowOption2button,R.id.ERowOption3button};
public ElectionOptionAdapter(Activity context, int length, String[] options, String[] description) {
super(context, R.layout.election_type_options,options);
this.context = context;
this.options = options;
this.description = description;
noOption=options.length;
optionText = new TextView[noOption];
optionDescription = new TextView[noOption];
optionImage = new RelativeLayout[noOption];
optionButton = new Button[noOption];
}
@Override
public int getCount() {
return 1;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = context.getLayoutInflater();
View card = inflater.inflate(R.layout.election_type_options, parent, false);
for (int i = 1+(3*position); i <= Math.min(3+(3*position),options.length); i++) {
optionText[i-1] = (TextView) card.findViewById(text[(i%4)-1]);
optionDescription[i-1] = (TextView) card.findViewById(des[(i%4)-1]);
optionImage[i-1] = (RelativeLayout) card.findViewById(img[(i%4)-1]);
optionButton[i-1] = (Button) card.findViewById(but[(i%4)-1]);
//The error message points here
optionImage[i-1].setVisibility(View.VISIBLE);
optionText[i-1].setText(options[i-1]);
optionDescription[i-1].setText(description[i-1]);
}
optionButton[0].setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
visibilityChange(0);
}
});
optionButton[1].setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
visibilityChange(1);
}
});
optionButton[2].setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
visibilityChange(2);
}
});
optionButton[3].setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
visibilityChange(3);
}
});
optionButton[4].setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
visibilityChange(4);
}
});
optionButton[5].setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
visibilityChange(5);
}
});
return card;
}
private void visibilityChange(int pos){
if(optionDescription[pos].getVisibility()==View.VISIBLE)
optionDescription[pos].setVisibility(View.INVISIBLE);
else
optionDescription[pos].setVisibility(View.VISIBLE);
}
}
2) The Error Message:
java.lang.NullPointerException:
Attempt to invoke virtual method 'void android.widget.RelativeLayout.setVisibility(int)'
on a null object reference at com.package.ElectionOptionAdapter.getView(ElectionOptionAdapter.java:72)
3) The Layout File :
<?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="horizontal"
android:paddingBottom="5dp"
android:paddingTop="5dp">
<RelativeLayout
android:tag="@+id/ERowOption1Img"
android:layout_width="120dp"
android:layout_height="120dp"
android:layout_marginLeft="2dp"
android:layout_marginRight="4dp"
android:visibility="invisible">
<TextView
android:tag="@+id/ERowOption1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:minHeight="25dp"
android:textStyle="bold"
android:text=" A) Gaurav Jindal"
android:layout_alignParentBottom="true" />
<TextView
android:background="#FFFFFF"
android:tag="@+id/ERowOption1des"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:visibility="invisible"/>
<Button
android:tag="@+id/ERowOption1button"
android:layout_width="20dp"
android:layout_height="20dp"
android:layout_alignParentTop="true"
android:layout_alignParentRight="true"
android:background="@drawable/info_election_option"/>
</RelativeLayout>
<RelativeLayout
android:tag="@+id/ERowOption2Img"
android:layout_width="120dp"
android:layout_height="120dp"
android:layout_marginLeft="2dp"
android:layout_marginRight="4dp"
android:visibility="invisible">
<TextView
android:tag="@+id/ERowOption2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:minHeight="25dp"
android:textStyle="bold"
android:text=" A) Gaurav Jindal"
android:layout_alignParentBottom="true" />
<TextView
android:tag="@+id/ERowOption2des"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:visibility="invisible"/>
<Button
android:tag="@+id/ERowOption2button"
android:layout_width="20dp"
android:layout_height="20dp"
android:layout_alignParentTop="true"
android:layout_alignParentRight="true"
android:background="@drawable/info_election_option"/>
</RelativeLayout>
<RelativeLayout
android:tag="@+id/ERowOption3Img"
android:layout_width="120dp"
android:layout_height="120dp"
android:layout_marginLeft="2dp"
android:layout_marginRight="4dp"
android:visibility="invisible">
<TextView
android:tag="@+id/ERowOption3"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:minHeight="25dp"
android:textStyle="bold"
android:text=" A) Gaurav Jindal"
android:layout_alignParentBottom="true" />
<TextView
android:tag="@+id/ERowOption3des"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:visibility="invisible"/>
<Button
android:tag="@+id/ERowOption3button"
android:layout_width="20dp"
android:layout_height="20dp"
android:layout_alignParentTop="true"
android:layout_alignParentRight="true"
android:background="@drawable/info_election_option"/>
</RelativeLayout>
</LinearLayout>
4) The RecyclerAdapter which calls ListAdapter mentioned above is:
public class FeedAdapter extends RecyclerView.Adapter<FeedAdapter.ViewHolder> {
JSONArray jsonArray;
Activity context;
public static class ViewHolder extends RecyclerView.ViewHolder {
TextView userid,question;
ImageView userdp;
ListView optionList;
public ViewHolder(View card) {
super(card);
userid = (TextView) card.findViewById(R.id.useridInCard);
question = (TextView) card.findViewById(R.id.questionInCard);
optionList = (ListView) card.findViewById(R.id.optionInCard);
}
}
FeedAdapter(Activity context,JSONArray jsonArray){
this.context=context;
this.jsonArray = jsonArray;
}
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.ques_card,parent,false);
ViewHolder viewHolder = new ViewHolder(view);
return viewHolder;
}
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
try {
JSONObject currentFeed = jsonArray.getJSONObject(position);
holder.userid.setText(currentFeed.getString("_id"));
holder.question.setText(currentFeed.getString("Question"));
int noOptions = currentFeed.getInt("noOption");
String[] option = new String[noOptions];
for(int i=1;i<=noOptions;i++)
option[i-1]=optionName(i)+currentFeed.getString("Option"+i);
String[] description = new String[noOptions];
for(int i=1;i<=noOptions;i++)
description[i-1]=currentFeed.getString("Description"+i);
ElectionOptionAdapter electionAdapter;
if(noOptions<=3)
electionAdapter= new ElectionOptionAdapter(context,1,option,description);
else
electionAdapter= new ElectionOptionAdapter(context,2,option,description);
holder.optionList.setAdapter(electionAdapter);
} catch (JSONException e) {
e.printStackTrace();
}
}
@Override
public int getItemCount() {
return 1;
}
}
In the Layout's xml file you should be using the attribute
android:id="@+id/foobar"
instead of
android:tag="@+id/foobar"