I don't know what make problem that show follower follow list, it was working but after few days later (maybe there is possbility i touch something...) it didn't working
what makes it error NullPointerException?
This is my Error
2019-06-17 11:53:31.158 8298-8298/com.example.blogapp E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.blogapp, PID: 8298
java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference
at com.example.together.Activities.FollowersActivity$5.onDataChange(FollowersActivity.java:157)
at com.google.firebase.database.Query$1.onDataChange(com.google.firebase:firebase-database@@17.0.0:184)
at com.google.firebase.database.core.ValueEventRegistration.fireEvent(com.google.firebase:firebase-database@@17.0.0:75)
at com.google.firebase.database.core.view.DataEvent.fire(com.google.firebase:firebase-database@@17.0.0:63)
at com.google.firebase.database.core.view.
Nothing showing redline ... just null point
This is my btn that i clicked*
followers.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(getContext(), FollowersActivity.class);
intent.putExtra("id", profileid);
intent.putExtra("title","followers");
startActivity(intent);
}
});
following.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(getContext(), FollowersActivity.class);
intent.putExtra("id", profileid);
intent.putExtra("title","following");
startActivity(intent);
}
});
This is my FollowersActivity
package com.example.together.Activities;
import android.content.Intent;
import android.support.annotation.NonNull;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.Toolbar;
import android.view.View;
import com.example.together.Adapter.UserAdapter;
import com.example.together.Model.User;
import com.example.together.R;
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 java.util.ArrayList;
import java.util.List;
public class FollowersActivity extends AppCompatActivity {
String id;
String title;
List<String> idList;
RecyclerView recyclerView;
UserAdapter userAdapter;
List<User> userList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_followers);
Intent intent = getIntent();
id = intent.getStringExtra("id");
title = intent.getStringExtra("title");
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
toolbar.setNavigationOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
finish();
}
});
recyclerView = findViewById(R.id.recycler_view);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
userList = new ArrayList<>();
userAdapter = new UserAdapter(this, userList, false);
recyclerView.setAdapter(userAdapter);
idList = new ArrayList<>();
switch (title){
case "likes":
getLikes();
break;
case "following":
getFollowing();
break;
case "followers":
getFollowers();
break;
}
}
private void getLikes() {
DatabaseReference reference = FirebaseDatabase.getInstance().getReference("Likes")
.child(id);
reference.addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
idList.clear();
for (DataSnapshot snapshot : dataSnapshot.getChildren()){
idList.add(snapshot.getKey());
}
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
}
private void getFollowing(){
DatabaseReference reference = FirebaseDatabase.getInstance().getReference("Follow")
.child(id).child("following");
reference.addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
idList.clear();
for (DataSnapshot snapshot : dataSnapshot.getChildren()){
idList.add(snapshot.getKey());
}
showUsers();
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
}
private void getFollowers(){
DatabaseReference reference = FirebaseDatabase.getInstance().getReference("Follow")
.child(id).child("followers");
reference.addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
idList.clear();
for (DataSnapshot snapshot : dataSnapshot.getChildren()){
idList.add(snapshot.getKey());
}
showUsers();
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
}
private void showUsers(){
DatabaseReference reference = FirebaseDatabase.getInstance().getReference("Users");
reference.addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
userList.clear();
for (DataSnapshot snapshot : dataSnapshot.getChildren()){
User user = snapshot.getValue(User.class);
for (String id : idList){
if (user.getId().equals(id)){
userList.add(user);
}
}
}
userAdapter.notifyDataSetChanged();
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
}
}
