I have been getting this error since I implemented the
public void getOtherAnimals(){
DatabaseReference otherAnimalDb = FirebaseDatabase.getInstance().getReference().child("Users").child(animalTwo);
otherAnimalDb.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(DataSnapshot snapshot, String s) {
if (snapshot.exists() && !snapshot.child("connections").child("no").hasChild(currentUId) && !snapshot.child("connections").child("yes").hasChild(currentUId)){
Cards item = new Cards(snapshot.getKey(), snapshot.child("name").getValue().toString());
rowItems.add(item);
arrayAdapter.notifyDataSetChanged();
}
}
section of code, the program worked beautifully before. I have done my reading on NullPointerExceptions but I don't have enough experience working with them to find the issue. I understand my program is pointing to a null object, but I cannot find it.
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.android.adoptme, PID: 20525
java.lang.NullPointerException: Attempt to invoke interface method 'int java.lang.CharSequence.length()' on a null object reference
at java.util.regex.Matcher.reset(Matcher.java:177)
at java.util.regex.Matcher.<init>(Matcher.java:90)
at java.util.regex.Pattern.matcher(Pattern.java:297)
at com.google.firebase.database.core.utilities.Validation.isValidPathString(Validation.java:40)
at com.google.firebase.database.core.utilities.Validation.validatePathString(Validation.java:44)
at com.google.firebase.database.DataSnapshot.hasChild(DataSnapshot.java:80)
at com.example.android.adoptme.MainActivity$5.onChildAdded(MainActivity.java:186)
at com.google.firebase.database.core.ChildEventRegistration.fireEvent(ChildEventRegistration.java:79)
at com.google.firebase.database.core.view.DataEvent.fire(DataEvent.java:63)
at com.google.firebase.database.core.view.EventRaiser$1.run(EventRaiser.java:55)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Here is my code: (And yes I am aware that there is probably a better way to write it, I am still working on it and refining it with research).
package com.example.android.adoptme;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.FitWindowsViewGroup;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Toast;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
import com.google.firebase.database.ChildEventListener;
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.lorentzos.flingswipe.SwipeFlingAdapterView;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity {
private Cards cards_data[];
private arrayAdapter arrayAdapter;
private int i;
private FirebaseAuth firebaseAuth;
private String currentUId;
private DatabaseReference petDb;
ListView listView;
List<Cards> rowItems;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
petDb = FirebaseDatabase.getInstance().getReference().child("Users");
firebaseAuth = FirebaseAuth.getInstance();
checkAnimalType();
rowItems = new ArrayList<Cards>();
arrayAdapter = new arrayAdapter(this, R.layout.item, rowItems);
SwipeFlingAdapterView flingContainer = (SwipeFlingAdapterView) findViewById(R.id.frame);
flingContainer.setAdapter(arrayAdapter);
flingContainer.setFlingListener(new SwipeFlingAdapterView.onFlingListener() {
@Override
public void removeFirstObjectInAdapter() {
// this is the simplest way to delete an object from the Adapter (/AdapterView)
Log.d("LIST", "removed object!");
rowItems.remove(0);
arrayAdapter.notifyDataSetChanged();
}
@Override
public void onLeftCardExit(Object dataObject) {
Cards obj = (Cards) dataObject;
String userId = obj.getUserId();
petDb.child(userId).child(userId).child("connections").child("no").child(currentUId).setValue(true);
makeToast(MainActivity.this, "Left!");
}
@Override
public void onRightCardExit(Object dataObject) {
Cards obj = (Cards) dataObject;
String userId = obj.getUserId();
petDb.child(userId).child(userId).child("connections").child("yes").child(currentUId).setValue(true);
makeToast(MainActivity.this, "Right!");
}
@Override
public void onAdapterAboutToEmpty(int itemsInAdapter) {
}
@Override
public void onScroll(float scrollProgressPercent) {
}
});
// Optionally add an OnItemClickListener
flingContainer.setOnItemClickListener(new SwipeFlingAdapterView.OnItemClickListener() {
@Override
public void onItemClicked(int itemPosition, Object dataObject) {
makeToast(MainActivity.this, "Clicked!");
}
});
}
static void makeToast(Context ctx, String s){
Toast.makeText(ctx, s, Toast.LENGTH_SHORT).show();
}
private String animalOne, animalTwo;
public void checkAnimalType(){
final FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();
DatabaseReference dogDb = FirebaseDatabase.getInstance().getReference().child("Users").child("Dog");
dogDb.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded( DataSnapshot snapshot, String s) {
if (snapshot.getKey().equals(user.getUid())){
animalOne = "Dog";
animalTwo = "Cat";
getOtherAnimals();
}
}
@Override
public void onChildChanged(DataSnapshot snapshot, String s) {
}
@Override
public void onChildRemoved(DataSnapshot snapshot) {
}
@Override
public void onChildMoved(DataSnapshot snapshot, String s) {
}
@Override
public void onCancelled(DatabaseError error) {
}
});
DatabaseReference catDb = FirebaseDatabase.getInstance().getReference().child("Users").child("Cat");
catDb.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(DataSnapshot snapshot, String s) {
if (snapshot.getKey().equals(user.getUid())){
animalOne = "Cat";
animalTwo = "Dog";
getOtherAnimals();
}
}
@Override
public void onChildChanged(DataSnapshot snapshot, String s) {
}
@Override
public void onChildRemoved( DataSnapshot snapshot) {
}
@Override
public void onChildMoved(DataSnapshot snapshot, String s) {
}
@Override
public void onCancelled(DatabaseError error) {
}
});
}
public void getOtherAnimals(){
DatabaseReference otherAnimalDb = FirebaseDatabase.getInstance().getReference().child("Users").child(animalTwo);
otherAnimalDb.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(DataSnapshot snapshot, String s) {
if (snapshot.exists() && !snapshot.child("connections").child("no").hasChild(currentUId) && !snapshot.child("connections").child("yes").hasChild(currentUId)){
Cards item = new Cards(snapshot.getKey(), snapshot.child("name").getValue().toString());
rowItems.add(item);
arrayAdapter.notifyDataSetChanged();
}
}
@Override
public void onChildChanged(DataSnapshot snapshot, String s) {
}
@Override
public void onChildRemoved(DataSnapshot snapshot) {
}
@Override
public void onChildMoved(DataSnapshot snapshot, String s) {
}
@Override
public void onCancelled(DatabaseError error) {
}
});
}
public void logoutUser (View view){
firebaseAuth.signOut();
Intent intent = new Intent (MainActivity.this, LoginRegistration.class);
startActivity(intent);
}
}
I appreciate any help you can provide me. Thanks in advance.
