I took this adapter from the internet and I got a problem:
Fatal Exception: java.lang.NullPointerException
Attempt to invoke virtual method 'void android.widget.ImageView.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
.Consts.CustomFriendsRequets.getView
Here CustomFriendRequest is my adapter, and its copy works fine, but this one doesn't want. The error refers to line 104, namely viewHolder.add.setOnClickListener (v ->. I spent several days going through the code, trying to figure out what was wrong.
Here is the complete adapter code. CustomFriendsRequets:
class CustomFriendsRequets extends ArrayAdapter<addFriends> implements View.OnClickListener{
private ArrayList<addFriends> dataSet;
private String uid, uid2;
private DatabaseReference isRef;
Context mContext;
// View lookup cache
private static class ViewHolder {
TextView txtName;
TextView txtType;
ImageView info;
ImageView add;
ImageView del;
}
public CustomFriendsRequets(ArrayList<addFriends> data, Context context) {
super(context, R.layout.friends_requests_item, data);
this.dataSet = data;
this.mContext=context;
}
@Override
public void onClick(View v) {
int position=(Integer) v.getTag();
Object object= getItem(position);
addFriends dataModel=(addFriends) object;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// Get the data item for this position
addFriends dataModel = getItem(position);
// Check if an existing view is being reused, otherwise inflate the view
ViewHolder viewHolder; // view lookup cache stored in tag
if (convertView == null) {
viewHolder = new ViewHolder();
LayoutInflater inflater = LayoutInflater.from(getContext());
convertView = inflater.inflate(R.layout.friends_item, parent, false);
viewHolder.txtName = convertView.findViewById(R.id.tvDescr);
viewHolder.txtType = convertView.findViewById(R.id.tvPrice);
viewHolder.info = convertView.findViewById(R.id.uImgreqs);
viewHolder.add = convertView.findViewById(R.id.ibAdd);
viewHolder.del = convertView.findViewById(R.id.ibDel);
convertView.setTag(viewHolder);
} else {
viewHolder = (ViewHolder) convertView.getTag();
}
FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();if(user!=null){uid=user.getUid();}
uid2 = dataModel.uid2;
viewHolder.txtName.setText(dataModel.username1);
viewHolder.txtType.setText("хочет добавить вас в друзья");
viewHolder.info.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(getContext(), EnemyProfile.class);
intent.putExtra(Constant.UID, dataModel.uid2);
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
v.getContext().startActivity(intent);
}
});
isRef = FirebaseDatabase.getInstance().getReference();
viewHolder.add.setOnClickListener(v -> //error here
isRef.child("Users").child("info").child(uid2).addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot snapshot) {
Users info = snapshot.getValue(Users.class);
if (info!=null){
String name = info.username;
String id = info.uid;
addFriends adf = new addFriends(id, name);
isRef.child("Users").child(uid).child("Friends").setValue(adf).
addOnSuccessListener(aVoid ->
isRef.child("Users").child("info").child(uid).addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot snapshot1) {
Users minfo = snapshot1.getValue(Users.class);
if (minfo!=null){
String mname = minfo.username;
String mid = minfo.uid;
addFriends madf = new addFriends(mid, mname);
isRef.child("Users").child(uid2).child("Friends").setValue(madf)
.addOnSuccessListener(aVoid1 -> {
isRef.child("Users").child(uid).child("Friends-request").child(uid2).removeValue();
isRef.child("Users").child(uid2).child("Friends-request").child(uid).removeValue();
});
}
}
@Override
public void onCancelled(@NonNull DatabaseError error) {
Toast.makeText(getContext(), error.getMessage(), Toast.LENGTH_SHORT).show();
}
}));
}
}
@Override
public void onCancelled(@NonNull DatabaseError error) {
Toast.makeText(getContext(), error.getMessage(), Toast.LENGTH_SHORT).show();
}
}));
viewHolder.del.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
isRef.child("Users").child(uid).child("Friends-request").child(uid2).removeValue();
isRef.child("Users").child(uid2).child("Friends-request").child(uid).removeValue();
}
});
// Return the completed view to render on screen
return convertView;
}
}and here I call it in the activity on the listview:
private void getReqs() {
DatabaseReference isRef = FirebaseDatabase.getInstance().getReference().child("Users").child(uid).child("Friends-request");
ValueEventListener valueEventListener = new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot snapshot) {
if (reqsTemp.size() > 0){reqsTemp.clear();}
for (DataSnapshot ds : snapshot.getChildren()){
addFriends reqs = ds.getValue(addFriends.class);
if (reqs!=null) {
reqsTemp.add(reqs);
}
}
reqsadapter.notifyDataSetChanged();
}
@Override
public void onCancelled(@NonNull DatabaseError error) {
Toast.makeText(Friends.this, error.getMessage(), Toast.LENGTH_SHORT).show();
}
};
isRef.addValueEventListener(valueEventListener);
}by the way here is the element code from the adapter:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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="96dp"
android:orientation="horizontal">
<androidx.cardview.widget.CardView
android:id="@+id/cardViewsdd"
android:layout_width="86dp"
android:layout_height="86dp"
android:layout_marginStart="10dp"
android:layout_marginTop="5dp"
app:cardBackgroundColor="@color/common_google_signin_btn_text_dark_disabled"
app:cardCornerRadius="50dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
<ImageView
android:id="@+id/uImgreqs"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:src="@mipmap/ic_launcher_round"
android:contentDescription="@string/todo" />
</androidx.cardview.widget.CardView>
<LinearLayout
android:id="@+id/linearLayout1"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_marginStart="5dp"
android:layout_weight="1"
android:orientation="vertical">
<TextView
android:id="@+id/tvDescr"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="5dp"
android:text=""
android:textSize="20sp" />
<TextView
android:id="@+id/tvPrice"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="18dp"
android:text="" />
</LinearLayout>
<LinearLayout
android:layout_width="100dp"
android:layout_height="match_parent"
android:orientation="horizontal">
<ImageView
android:id="@+id/ibAdd"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1"
app:srcCompat="@android:drawable/ic_input_add" />
<ImageView
android:id="@+id/ibDel"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1"
app:srcCompat="@drawable/ic_dialog_close_light" />
</LinearLayout>
</LinearLayout>
the add button should record the id of both users to each other, and del accordingly delete the request. uImgreqs is just a photo of the user, and both textviews are user data of the username, etc. If anything needs to be added, I will be glad to add, because I am in despair, and the deadlines are running out
God, boooooo well noooo. Android Studio, I adore you.
I found a solution, it turned out that the problem was due to (v ->, I or the studio translated the OnClick function into a lambda and because of this it returned a null object ... 3 and a half days ... I spent more than three days on this, omg
viewHolder.add.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {});
No, it`s not win
uh, no, it didn't solve the problem completely and now throws an error on every imageView .setOnClicklistener ...
I found the problem, I misdated the label:
convertView = inflater.inflate(R.layout.friends_item, parent, false);
very unremarkable line, facepalm