我想在 recyclerview 中显示编辑文本数据，但它不起作用

Question

我想在 recyclerview 中显示编辑文本数据，但它不起作用请帮忙。当我在移动设备上运行应用程序时，如果它运行则会崩溃，然后应用程序不工作数据不会显示在 recyclerview 中。 当我在移动设备中运行应用程序时，如果它运行则它会崩溃，然后应用程序不工作数据不会显示在 recyclerview 中。当我在移动设备中运行应用程序时，如果它运行则它会崩溃，然后应用程序不工作数据不会显示在 recyclerview 中。

**Adapter Class**


package com.deitel.note;

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

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

import java.util.ArrayList;
import java.util.List;

public class myadapter {

    public class Adapter extends RecyclerView.Adapter<Adapter.Viewholder>{

        String Name;
        String Details;
        Context context;
        private List<modelclass> modelclassList;

        public Adapter(@NonNull MainActivity mainActivity, ArrayList<modelclass> list){
            this.context=mainActivity;
            this.modelclassList=list;
        }

        @NonNull
        @Override
        public Viewholder onCreateViewHolder(@NonNull ViewGroup viewGroup, int viewType) {

            View view= LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.item_layout,viewGroup,false);
            return new Viewholder(view);
        }

        @Override
        public void onBindViewHolder(@NonNull Viewholder holder, int position) {
        Name=modelclassList.get(position).getName();
        Details=modelclassList.get(position).getDetails();

        }

        @Override
        public int getItemCount() {
            return modelclassList.size();
        }


        class Viewholder extends RecyclerView.ViewHolder{
            public TextView name;
            public TextView details;
            public Button btn_add;
            public Viewholder(@NonNull View itemView) {
                super(itemView);
                name=itemView.findViewById(R.id.text_name);
                details=itemView.findViewById(R.id.text_details);
                btn_add=itemView.findViewById(R.id.btn_add);
                btn_add.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View view) {
                    }
                });


            }
        }
    }
}


**Model Class**


package com.deitel.note;

import android.telephony.SignalStrength;

public class modelclass {

    String name;
    String details;
    public modelclass(String name, String details) {
        this.name = name;
        this.details = details;
    }
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getDetails() {
        return details;
    }

    public void setDetails(String details) {
        this.details = details;
    }
}


**Main Activity**


package com.deitel.note;

import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.os.Bundle;
import android.widget.Adapter;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

    RecyclerView recyclerView;
  Adapter adapter;
    ArrayList<modelclass> list=new ArrayList<>();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

    recyclerView.findViewById(R.id.recyclerview);

        LinearLayoutManager mlayoutmanager=new LinearLayoutManager(this);
        mlayoutmanager.setOrientation(RecyclerView.VERTICAL);
        recyclerView.setLayoutManager(mlayoutmanager);



    }
}

Answer 1

首先，您没有在适配器内的视图上调用setText。

第二。当您设置类变量String Name;、String Details; 时，它们只能是一个值，这意味着每次显示适配器中的项目并调用onBind 方法时，您只是替换了变量。

第三。你的代码中有一些其他警告（代码样式和东西），所以我把它拿走了并为你清理了它。 :)

适配器类

public class MyAdapter { //Class names should be in [pascalcase][1]

    public class Adapter extends RecyclerView.Adapter<Adapter.ViewHolder> {

        private List<ModelClass> elements;

        /**
         * //You don't need context here, you can easily cause a memory leak.
         * @param elements should be a list and not an [ArrayList] that way your not limited to [ArrayList] but [ArrayList] will work
         */
        public Adapter(List<ModelCase> elements) {
            this.elements = elements;
        }

        @NonNull
        @Override
        public ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int viewType) {
            LayoutInflater inflater = LayoutInflater.from(viewGroup.getContext());
            return new ViewHolder(inflater.inflate(R.layout.item_layout, viewGroup, false));
        }

        @Override
        public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
            ModelClass model = modelclassList.get(position);

            holder.name.setText(model.getName());
            holder.details.setText(model.getDetails());
        }

        @Override
        public int getItemCount() {
            return elements.size();
        }

        protected class ViewHolder extends RecyclerView.ViewHolder { //Class names should be in [pascalcase][1]
            TextView name; //Class names should be in [camelCase][2]
            TextView details; //Class names should be in [camelCase][2]
            Button addButton; //Class names should be in [camelCase][2]

            public ViewHolder(@NonNull View itemView) {
                super(itemView);
                name = itemView.findViewById(R.id.text_name);
                details = itemView.findViewById(R.id.text_details);
                addButton = itemView.findViewById(R.id.btn_add);
                addButton.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View view) {
                    }
                });
            }
        }
    }
}

模型类

package com.deitel.note;

import android.telephony.SignalStrength;

public class ModelClass { //Class names should be in [pascalcase][2]

    private String name;
    private String details;

    public ModelClass(String name, String details) {
        this.name = name;
        this.details = details;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getDetails() {
        return details;
    }

    public void setDetails(String details) {
        this.details = details;
    }
}

主要活动

package com.deitel.note;

import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.os.Bundle;
import android.widget.Adapter;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

    RecyclerView recyclerView;
    MyAdapter.Adapter adapter;
    ArrayList<ModelClass> list = new ArrayList<>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        recyclerView = findViewById(R.id.recyclerview);

        LinearLayoutManager layoutmanager = new LinearLayoutManager(this); //LinearLayoutManager is RecyclerView.VERTICAL by default
        recyclerView.setLayoutManager(layoutmanager);

        //Fill in the list before creating the adapter
        adapter = new MyAdapter.Adapter(list);
        recyclerView.setAdapter(adapter);

    }
}