Firebase DB-linked Recycler 视图有错误

Question

我是 Android 开发的初学者。 Firebase DB-linked Recycler 视图有错误。 Frag1.java.

中有两个错误

Frag1.java
'LinearLayoutManager(android.content.Context)' in 'androidx.recyclerview.widget.LinearLayoutManager' cannot be applied to '(softcampus.co.myapplication.Frag1)'
'ContentAdapter(java.util.ArrayList<softcampus.co.myapplication.Content>, android.content.Context)' in 'softcampus.co.myapplication.ContentAdapter' cannot be applied to '(java.util.ArrayList<softcampus.co.myapplication.Content>, softcampus.co.myapplication.Frag1)'

我很难过，因为错误没有通过搜索解决...

Frag1.java

package softcampus.co.myapplication;

import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.LinearLayout;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

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 org.w3c.dom.Text;

import java.util.ArrayList;

public class Frag1 extends Fragment {

    private View view;
    private RecyclerView recyclerView;
    private RecyclerView.Adapter adapter;
    private RecyclerView.LayoutManager layoutManager;
    private ArrayList<Content> arrayList;
    private FirebaseDatabase database;
    private DatabaseReference databaseReference;

    TextView main_name;
    TextView main_board;
    Button main_plus;

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        view = inflater.inflate(R.layout.frag1_home, container, false);

        recyclerView = (RecyclerView)view.findViewById(R.id.recyclerView);
        recyclerView.setHasFixedSize(true);
        layoutManager = new LinearLayoutManager(this);
        recyclerView.setLayoutManager(layoutManager);
        arrayList = new ArrayList<>(); 

        database = FirebaseDatabase.getInstance(); 

        databaseReference = database.getReference("Content"); 
        databaseReference.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                
                arrayList.clear();
                for(DataSnapshot snapshot : dataSnapshot.getChildren()){ 
                    Content content = snapshot.getValue(Content.class); 
                    arrayList.add(content); 
                }
                adapter.notifyDataSetChanged();
            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {
                Log.e("Frag1",String.valueOf(databaseError.toException()));
            }
        });

        adapter = new ContentAdapter(arrayList, this);
        recyclerView.setAdapter(adapter);

        main_name = (TextView)view.findViewById(R.id.main_name);
        main_board = (TextView) view.findViewById(R.id.main_board);
        main_plus = (Button) view.findViewById(R.id.main_plus);

        main_plus.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent  = new Intent(view.getContext(), Campaign_registration.class);
                startActivity(intent);
            }
        });

        return view;
    }

}

frag1_home.xml

<?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"
    android:orientation="vertical">


    <TextView
        android:id="@+id/main_name"
        android:layout_width="365dp"
        android:layout_height="wrap_content"
        android:text="안녕하세요, OOO님!"
        android:textSize="25sp"
        android:textStyle="bold"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.1" />

    <Button
        android:id="@+id/main_plus"
        android:layout_width="35dp"
        android:layout_height="35dp"
        android:background="@drawable/ic_baseline_add_circle_24"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.906"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.181" />

    <TextView
        android:id="@+id/main_board"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="게시판"
        android:textSize="22sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.148"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.186" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="560dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="1.0">

        <ScrollView
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <androidx.recyclerview.widget.RecyclerView
                android:id="@+id/recyclerView"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:orientation="vertical"
                app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager" />

        </ScrollView>


    </LinearLayout>

</androidx.constraintlayout.widget.ConstraintLayout>

Content.java

package softcampus.co.myapplication;

public class Content {
    private String pro_img;
    private String campagin_name;
    private int token_goal;
    private String text;

    public Content(){};

    public String getPro_img() {
        return pro_img;
    }

    public void setPro_img(String pro_img) {
        this.pro_img = pro_img;
    }

    public String getCampagin_name() {
        return campagin_name;
    }

    public void setCampagin_name(String campagin_name) {
        this.campagin_name = campagin_name;
    }

    public int getToken_goal() {
        return token_goal;
    }

    public void setToken_goal(int token_goal) {
        this.token_goal = token_goal;
    }

    public String getText() { return text;}

    public void setText(String text) { this.text = text; }
}

ContentAdapter.java

package softcampus.co.myapplication;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import com.bumptech.glide.Glide;

import java.util.ArrayList;

public class ContentAdapter extends RecyclerView.Adapter<ContentAdapter.ContentViewHolder> {

    private ArrayList<Content> arrayList;
    private Context context;


    public ContentAdapter(ArrayList<Content> arrayList, Context context) {
        this.arrayList = arrayList;
        this.context = context;
    }


    @NonNull
    @Override
    public ContentViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.content_item,parent,false);
        ContentViewHolder holder = new ContentViewHolder(view);

        return holder;
    }

    @Override
    public void onBindViewHolder(@NonNull ContentViewHolder holder, int position) {
        Glide.with(holder.itemView)
                .load(arrayList.get(position).getPro_img())
                .into(holder.iv_profile);
        holder.tv_name.setText(arrayList.get(position).getCampagin_name());
        holder.tv_goal.setText(arrayList.get(position).getToken_goal());
    }

    @Override
    public int getItemCount() {
        //삼항 연산자
        return (arrayList != null ? arrayList.size() : 0);
    }

    public class ContentViewHolder extends RecyclerView.ViewHolder {
        ImageView iv_profile;
        TextView tv_name;
        TextView tv_goal;

        public ContentViewHolder(@NonNull View itemView) {
            super(itemView);
            this.iv_profile = itemView.findViewById(R.id.iv_profile);
            this.tv_name = itemView.findViewById(R.id.tv_name);
            this.tv_goal = itemView.findViewById(R.id.tv_goal);
        }
    }
}

content_item.xml

<?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"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

            <ImageView
                android:id="@+id/iv_profile"
                android:layout_width="80dp"
                android:layout_height="80dp"
                android:layout_margin="5dp"
                app:srcCompat="@android:drawable/ic_menu_gallery" />

                <LinearLayout
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:orientation="vertical"
                    android:layout_marginLeft="5dp">

                    <TextView
                        android:id="@+id/tv_name"
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:text="캠페인명"
                        android:textSize="27sp"
                        android:layout_marginTop="14dp"/>

                    <TextView
                        android:id="@+id/tv_goal"
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:text="목표 토큰"
                        android:textSize="18sp"
                        android:layout_marginTop='3dp'/>

                </LinearLayout>
    </LinearLayout>

</LinearLayout>

这个问题已经困扰我好几个星期了，我似乎找不到解决办法。在此先感谢您的帮助。

Answer 1

对于第一个错误，要么以编程方式设置 LinearLayoutManager，要么在 xml 中设置，但不要同时使用两者，并在以编程方式设置时使用 requireContext() 而不是这个
```
  layoutManager = new LinearLayoutManager(this);
  layoutManager = new LinearLayoutManager(requireContext());
```

对于第二个你在片段中使用它作为上下文，使用 requireContext()

  adapter = new ContentAdapter(arrayList, this);
  adapter = new ContentAdapter(arrayList, requireContext());

第三，为什么你的recyclerview在scrollview里面，在linearlayout里面？考虑将其作为子项添加到 ConstraintLayout？
四、考虑去掉content_item
中嵌套的LinearLayout

Firebase DB-linked Recycler 视图有错误

Firebase DB-linked Recycler view has an error

java

android

firebase

firebase-realtime-database

android-recyclerview