无法使用自定义适配器从 firebase 获取数据，“Сan 不能为子 () 中的参数 pathString 传递 null”
Can't get data from firebase using custom adapter, "Сan't pass null for argument pathString in child ()"
我不太明白自定义数组适配器是如何工作的，但其中一个已经在我的项目中工作了，所以我决定也将它添加到其他列表中。
我不确定，但我认为问题出在从 addFriends 到 Message
的重新查看中
private void getFriends(){
DatabaseReference isRef = FirebaseDatabase.getInstance().getReference().child("Users").child(uid).child("Friends");
ValueEventListener valueEventListener = new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot snapshot) {
if(listTemp.size() > 0){listTemp.clear();}
for (DataSnapshot ds : snapshot.getChildren()){
addFriends addFriend = ds.getValue(addFriends.class);
if(addFriend != null){ //переоброзование в вид с чатом
String message = "put message is here, don`t forget. @chatID";
String nameuser = addFriend.username1;
String userID = addFriend.uid2;
Message mainFriends = new Message(message, nameuser, userID);
if(mainFriends != null) {
listTemp.add(mainFriends);
}
}
}
adapter.notifyDataSetChanged();
}
@Override
public void onCancelled(@NonNull DatabaseError error) {
}
};
isRef.addValueEventListener(valueEventListener);
}
问题正好指向private void getFriends(){
问题：
Unable to start activity ComponentInfo{esport.inyourlife.myproektlink.Profile.Friends}: java.lang.NullPointerException: Can't pass null for argument 'pathString' in child() android.app.ActivityThread.performLaunchActivity
还有我借用的适配器代码：
package #.Consts;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import com.google.android.material.snackbar.Snackbar;
import java.util.ArrayList;
import esport.inyourlife.insport.R;
public class CustomAdapter extends ArrayAdapter<Message> implements View.OnClickListener{
private ArrayList<Message> dataSet;
Context mContext;
// View lookup cache
private static class ViewHolder {
TextView txtName;
TextView txtType;
ImageView info;
}
public CustomAdapter(ArrayList<Message> data, Context context) {
super(context, R.layout.msg_center_item, data);
this.dataSet = data;
this.mContext=context;
}
@Override
public void onClick(View v) {
int position=(Integer) v.getTag();
Object object= getItem(position);
Message dataModel=(Message) object;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// Get the data item for this position
Message 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.msg_center_item, parent, false);
viewHolder.txtName = convertView.findViewById(R.id.tvDescr);
viewHolder.txtType = convertView.findViewById(R.id.tvPrice);
viewHolder.info = convertView.findViewById(R.id.uImgg);
convertView.setTag(viewHolder);
} else {
viewHolder = (ViewHolder) convertView.getTag();
}
viewHolder.txtName.setText(dataModel.nameuser);
viewHolder.txtType.setText(dataModel.message);
// Return the completed view to render on screen
return convertView;
}
}
项目：
<?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="wrap_content"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:orientation="horizontal">
<androidx.cardview.widget.CardView
android:id="@+id/cardViewsdd"
android:layout_width="86dp"
android:layout_height="83dp"
android:layout_marginStart="16dp"
android:layout_marginTop="16dp"
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/uImgg"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:src="@mipmap/ic_launcher_round" />
</androidx.cardview.widget.CardView>
<LinearLayout
android:id="@+id/linearLayout1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginLeft="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>
<TextView
android:id="@+id/tvPrice"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="18dp"
android:text="">
</TextView>
</LinearLayout>
</LinearLayout>
如果所有 Friends.class 代码都能派上用场
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.Toast;
import com.google.android.material.tabs.TabLayout;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
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;
import esport.inyourlife.insport.Consts.CustomAdapter;
import esport.inyourlife.insport.Consts.CustomFriends;
import esport.inyourlife.insport.Consts.Message;
import esport.inyourlife.insport.Consts.addFriends;
import esport.inyourlife.insport.R;
import esport.inyourlife.insport.findtest;
public class Friends extends AppCompatActivity {
private final FirebaseAuth mAuth = FirebaseAuth.getInstance();
private ArrayAdapter adapter;
private ArrayList<Message> listTemp;
private String uid;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_friends);
setTitle("Друзья");
assert getSupportActionBar() != null; //null check
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setHomeButtonEnabled(true);
getFriends();
TabLayout tabs = findViewById(R.id.tabsFriends);
LinearLayout freq = findViewById(R.id.support_layout);
ListView friendList = findViewById(R.id.FriendList);
tabs.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
@Override
public void onTabSelected(TabLayout.Tab tab) {
int position = tab.getPosition();
if (position == 0) {
freq.setVisibility(View.GONE);
friendList.setVisibility(View.VISIBLE);
getFriends();
}
else if (position == 1) {
freq.setVisibility(View.VISIBLE);
friendList.setVisibility(View.GONE);
getReqs();
}
}
@Override
public void onTabUnselected(TabLayout.Tab tab) {
}
@Override
public void onTabReselected(TabLayout.Tab tab) {
}
});
ImageButton add = findViewById(R.id.addFriendToAll);
add.setOnClickListener(v -> {
startActivity(new Intent(this, findtest.class));
});
Button reqs = findViewById(R.id.reqs);
reqs.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startActivity(new Intent(Friends.this, friendsRequest.class));
}
});
listTemp = new ArrayList<>();
adapter = new CustomAdapter(listTemp, getApplicationContext());
friendList.setAdapter(adapter);
FirebaseUser user = mAuth.getCurrentUser();
if (user == null) {this.finish();}
if (user != null){
uid = user.getUid();
}
}
private void getFriends(){//получение друзей в 05/02 было из users/uid/friends
DatabaseReference isRef = FirebaseDatabase.getInstance().getReference().child("Users").child(uid).child("Friends");
ValueEventListener valueEventListener = new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot snapshot) {
if(listTemp.size() > 0){listTemp.clear();}
for (DataSnapshot ds : snapshot.getChildren()){
addFriends addFriend = ds.getValue(addFriends.class);
if(addFriend != null){ //переоброзование в вид с чатом
String message = "put message is here, don`t forget. @chatID";
String nameuser = addFriend.username1;
String userID = addFriend.uid2;
Message mainFriends = new Message(message, nameuser, userID);
if(mainFriends != null) {
listTemp.add(mainFriends);
}
}
}
adapter.notifyDataSetChanged();
}
@Override
public void onCancelled(@NonNull DatabaseError error) {
}
};
isRef.addValueEventListener(valueEventListener);
}
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(listData.size() > 0){listData.clear();}
for (DataSnapshot ds : snapshot.getChildren()) {
addFriends addFriendless;
addFriendless = ds.getValue(addFriends.class);
if (addFriendless != null) {
listData.add(addFriendless.username1);
}
}
adapter.notifyDataSetChanged();
}
@Override
public void onCancelled(@NonNull DatabaseError error) {
Toast.makeText(Friends.this, error.getMessage(), Toast.LENGTH_SHORT).show();
}
};
isRef.addValueEventListener(valueEventListener);
}*/
}
@Override
public boolean onSupportNavigateUp(){
finish();
return true;
}
}
顺便说一下，消息 class 本身
package #
public class Message {
public String message;
public String nameuser;
public String userID;
public Message(String message, String nameuser, String userID) {
this.message = message;
this.nameuser = nameuser;
this.userID = userID;
}
public Message() {
}
}
它在你的错误中说
Can't pass null for argument 'pathString' in child()
正如它所说的那样。很有可能你的uid等于null。在发送之前检查该变量。我可以在你的代码中看到你在给 uid 赋值之前调用 getFriends()，这导致了这个错误。
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_friends);
setTitle("Друзья");
assert getSupportActionBar() != null; //null check
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setHomeButtonEnabled(true);
FirebaseUser user = mAuth.getCurrentUser();
if (user == null) this.finish();
if (user != null){
uid = user.getUid();
}
getFriends();
在调用 getFriends()
之前获取 uid
我不太明白自定义数组适配器是如何工作的，但其中一个已经在我的项目中工作了，所以我决定也将它添加到其他列表中。 我不确定，但我认为问题出在从 addFriends 到 Message
的重新查看中private void getFriends(){
DatabaseReference isRef = FirebaseDatabase.getInstance().getReference().child("Users").child(uid).child("Friends");
ValueEventListener valueEventListener = new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot snapshot) {
if(listTemp.size() > 0){listTemp.clear();}
for (DataSnapshot ds : snapshot.getChildren()){
addFriends addFriend = ds.getValue(addFriends.class);
if(addFriend != null){ //переоброзование в вид с чатом
String message = "put message is here, don`t forget. @chatID";
String nameuser = addFriend.username1;
String userID = addFriend.uid2;
Message mainFriends = new Message(message, nameuser, userID);
if(mainFriends != null) {
listTemp.add(mainFriends);
}
}
}
adapter.notifyDataSetChanged();
}
@Override
public void onCancelled(@NonNull DatabaseError error) {
}
};
isRef.addValueEventListener(valueEventListener);
}
问题正好指向private void getFriends(){
问题：
Unable to start activity ComponentInfo{esport.inyourlife.myproektlink.Profile.Friends}: java.lang.NullPointerException: Can't pass null for argument 'pathString' in child() android.app.ActivityThread.performLaunchActivity
还有我借用的适配器代码：
package #.Consts;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import com.google.android.material.snackbar.Snackbar;
import java.util.ArrayList;
import esport.inyourlife.insport.R;
public class CustomAdapter extends ArrayAdapter<Message> implements View.OnClickListener{
private ArrayList<Message> dataSet;
Context mContext;
// View lookup cache
private static class ViewHolder {
TextView txtName;
TextView txtType;
ImageView info;
}
public CustomAdapter(ArrayList<Message> data, Context context) {
super(context, R.layout.msg_center_item, data);
this.dataSet = data;
this.mContext=context;
}
@Override
public void onClick(View v) {
int position=(Integer) v.getTag();
Object object= getItem(position);
Message dataModel=(Message) object;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// Get the data item for this position
Message 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.msg_center_item, parent, false);
viewHolder.txtName = convertView.findViewById(R.id.tvDescr);
viewHolder.txtType = convertView.findViewById(R.id.tvPrice);
viewHolder.info = convertView.findViewById(R.id.uImgg);
convertView.setTag(viewHolder);
} else {
viewHolder = (ViewHolder) convertView.getTag();
}
viewHolder.txtName.setText(dataModel.nameuser);
viewHolder.txtType.setText(dataModel.message);
// Return the completed view to render on screen
return convertView;
}
}
项目：
<?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="wrap_content"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:orientation="horizontal">
<androidx.cardview.widget.CardView
android:id="@+id/cardViewsdd"
android:layout_width="86dp"
android:layout_height="83dp"
android:layout_marginStart="16dp"
android:layout_marginTop="16dp"
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/uImgg"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:src="@mipmap/ic_launcher_round" />
</androidx.cardview.widget.CardView>
<LinearLayout
android:id="@+id/linearLayout1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginLeft="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>
<TextView
android:id="@+id/tvPrice"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="18dp"
android:text="">
</TextView>
</LinearLayout>
</LinearLayout>
如果所有 Friends.class 代码都能派上用场
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.Toast;
import com.google.android.material.tabs.TabLayout;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
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;
import esport.inyourlife.insport.Consts.CustomAdapter;
import esport.inyourlife.insport.Consts.CustomFriends;
import esport.inyourlife.insport.Consts.Message;
import esport.inyourlife.insport.Consts.addFriends;
import esport.inyourlife.insport.R;
import esport.inyourlife.insport.findtest;
public class Friends extends AppCompatActivity {
private final FirebaseAuth mAuth = FirebaseAuth.getInstance();
private ArrayAdapter adapter;
private ArrayList<Message> listTemp;
private String uid;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_friends);
setTitle("Друзья");
assert getSupportActionBar() != null; //null check
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setHomeButtonEnabled(true);
getFriends();
TabLayout tabs = findViewById(R.id.tabsFriends);
LinearLayout freq = findViewById(R.id.support_layout);
ListView friendList = findViewById(R.id.FriendList);
tabs.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
@Override
public void onTabSelected(TabLayout.Tab tab) {
int position = tab.getPosition();
if (position == 0) {
freq.setVisibility(View.GONE);
friendList.setVisibility(View.VISIBLE);
getFriends();
}
else if (position == 1) {
freq.setVisibility(View.VISIBLE);
friendList.setVisibility(View.GONE);
getReqs();
}
}
@Override
public void onTabUnselected(TabLayout.Tab tab) {
}
@Override
public void onTabReselected(TabLayout.Tab tab) {
}
});
ImageButton add = findViewById(R.id.addFriendToAll);
add.setOnClickListener(v -> {
startActivity(new Intent(this, findtest.class));
});
Button reqs = findViewById(R.id.reqs);
reqs.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startActivity(new Intent(Friends.this, friendsRequest.class));
}
});
listTemp = new ArrayList<>();
adapter = new CustomAdapter(listTemp, getApplicationContext());
friendList.setAdapter(adapter);
FirebaseUser user = mAuth.getCurrentUser();
if (user == null) {this.finish();}
if (user != null){
uid = user.getUid();
}
}
private void getFriends(){//получение друзей в 05/02 было из users/uid/friends
DatabaseReference isRef = FirebaseDatabase.getInstance().getReference().child("Users").child(uid).child("Friends");
ValueEventListener valueEventListener = new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot snapshot) {
if(listTemp.size() > 0){listTemp.clear();}
for (DataSnapshot ds : snapshot.getChildren()){
addFriends addFriend = ds.getValue(addFriends.class);
if(addFriend != null){ //переоброзование в вид с чатом
String message = "put message is here, don`t forget. @chatID";
String nameuser = addFriend.username1;
String userID = addFriend.uid2;
Message mainFriends = new Message(message, nameuser, userID);
if(mainFriends != null) {
listTemp.add(mainFriends);
}
}
}
adapter.notifyDataSetChanged();
}
@Override
public void onCancelled(@NonNull DatabaseError error) {
}
};
isRef.addValueEventListener(valueEventListener);
}
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(listData.size() > 0){listData.clear();}
for (DataSnapshot ds : snapshot.getChildren()) {
addFriends addFriendless;
addFriendless = ds.getValue(addFriends.class);
if (addFriendless != null) {
listData.add(addFriendless.username1);
}
}
adapter.notifyDataSetChanged();
}
@Override
public void onCancelled(@NonNull DatabaseError error) {
Toast.makeText(Friends.this, error.getMessage(), Toast.LENGTH_SHORT).show();
}
};
isRef.addValueEventListener(valueEventListener);
}*/
}
@Override
public boolean onSupportNavigateUp(){
finish();
return true;
}
}
顺便说一下，消息 class 本身
package #
public class Message {
public String message;
public String nameuser;
public String userID;
public Message(String message, String nameuser, String userID) {
this.message = message;
this.nameuser = nameuser;
this.userID = userID;
}
public Message() {
}
}
它在你的错误中说
Can't pass null for argument 'pathString' in child()
正如它所说的那样。很有可能你的uid等于null。在发送之前检查该变量。我可以在你的代码中看到你在给 uid 赋值之前调用 getFriends()，这导致了这个错误。
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_friends);
setTitle("Друзья");
assert getSupportActionBar() != null; //null check
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setHomeButtonEnabled(true);
FirebaseUser user = mAuth.getCurrentUser();
if (user == null) this.finish();
if (user != null){
uid = user.getUid();
}
getFriends();
在调用 getFriends()
uid