I need to update date in a ListAdapter , for this i display a dialog
composed by 2 EditTexts
and 1 Button
, the problem here is that when i click the "update" button in the dialog it throws
(android.view.View$OnClickListener)' on a null object reference
btw, im using firebase realtime database to save the data.
Stacktrace:
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference at com.example.notasderober.ReadNotes.showUpdateDialog(ReadNotes.java:106) at com.example.notasderober.ReadNotes.access$000(ReadNotes.java:33) at com.example.notasderober.ReadNotes$2.onItemClick(ReadNotes.java:77) at android.widget.AdapterView.performItemClick(AdapterView.java:330) at android.widget.AbsListView.performItemClick(AbsListView.java:1187) at android.widget.AbsListView$PerformClick.run(AbsListView.java:3179) at android.widget.AbsListView$3.run(AbsListView.java:4097) at android.os.Handler.handleCallback(Handler.java:938) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:223) at android.app.ActivityThread.main(ActivityThread.java:7656) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
CODE :
package com.example.notasderober;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.Toast;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.ValueEventListener;
import com.google.firebase.firestore.auth.User;
import org.checkerframework.checker.units.qual.A;
import java.util.ArrayList;
import java.util.List;
public class ReadNotes extends AppCompatActivity {
List<Users> notesList;
ListView listView;
Button updateButton;
View updateDialogView;
LayoutInflater inflater;
DatabaseReference studentDbRef;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_read_notes);
listView = findViewById(R.id.listview);
notesList = new ArrayList<>();
inflater = getLayoutInflater();
updateDialogView = inflater.inflate(R.layout.update_dialog,null);
updateButton = updateDialogView.findViewById(R.id.updateNoteButton);
studentDbRef =FirebaseDatabase.getInstance().getReference("Notas");
studentDbRef.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot snapshot) {
notesList.clear();
for (DataSnapshot studentDatasnap : snapshot.getChildren()){
Users notes = studentDatasnap.getValue(Users.class);
notesList.add(notes);
}
ListAdapter adapter = new ListAdapter(ReadNotes.this,notesList);
listView.setAdapter(adapter);
}
@Override
public void onCancelled(@NonNull DatabaseError error) {
}
});
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
Users students = notesList.get(i);
showUpdateDialog(students.getId(), students.getName());
}
});
}
//SHOW UPDATE DIALOG
private void showUpdateDialog (final String id, String name) {
Log.d("updateDialog","Dialog update");
final AlertDialog.Builder updateDialog = new AlertDialog.Builder(this);
updateDialog.setView(updateDialogView);
final EditText updateNote = findViewById(R.id.updateNoteText);
final EditText updateNoteContent = findViewById(R.id.updateContentText);
updateDialog.setTitle("Actualizando : " + name);
final AlertDialog alertDialog = updateDialog.create();
alertDialog.show();
updateButton.setOnClickListener(new View.OnClickListener() { // maybe here is the problem
@Override
public void onClick(View view) {
String noteTitle = updateNote.getText().toString();
String noteContent = updateNoteContent.getText().toString();
updateData(id,noteTitle,noteContent);
Toast.makeText(ReadNotes.this,"Nota actualizada",Toast.LENGTH_SHORT).show();
}
});
}
//UPDATE DATA IN DATABASE
private void updateData (String id, String name, String note) {
DatabaseReference dbRef = FirebaseDatabase.getInstance().getReference("Notas").child(id);
Users noteEx = new Users(id,name,note);
dbRef.setValue(noteEx);
}
XML file:
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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=".ReadNotes">
<TextView
android:id="@+id/textView5"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Saved notes"
android:textSize="34sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.497"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.023" />
<ListView
android:id="@+id/listview"
android:layout_width="409dp"
android:layout_height="668dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.968" />
</androidx.constraintlayout.widget.ConstraintLayout>
XML dialog file :
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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">
<EditText
android:id="@+id/updateNoteText"
android:layout_width="289dp"
android:layout_height="144dp"
android:ems="10"
android:hint="Nota"
android:inputType="text"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.368"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.054" />
<EditText
android:id="@+id/updateContentText"
android:layout_width="286dp"
android:layout_height="127dp"
android:ems="10"
android:hint="Contenido nota"
android:inputType="text"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.381"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.462" />
<Button
android:id="@+id/updateNoteButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Modificar"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.976" />
</androidx.constraintlayout.widget.ConstraintLayout>
I tried checking that the button is correctly declared in the xml file, and also as a constant field, but the error is still there.
You should call findViewById
from the ViewGroup which your particular view is belong to.
Just replace these lines:
final EditText updateNote = findViewById(R.id.updateNoteText);
final EditText updateNoteContent = findViewById(R.id.updateContentText);
to
final EditText updateNote = updateDialogView.findViewById(R.id.updateNoteText);
final EditText updateNoteContent = updateDialogView.findViewById(R.id.updateContentText);