Question

在之前的调试之后，我断言我的数据库确实正常工作，但即使它出现了，虽然我已正确设置awk ' BEGIN {count=0;} { if ($1 == "A") count+=1} end {print $count}'，但数据没有显示。

我在主活动中连接到我的数据库，并使用界面将信息传递给我的片段。然后将此ReycleViewAdapter数据作为参数传递给我的适配器，以便在List<GlobalLists>方法中使用;之前我在列表视图中呈现了这些数据但是当我想要实时更新时，我不得不切换到循环视图。有人能指出这里发生了什么吗？

onBind对象是我省略的接口，因为它只包含数据检索方法，

我的XML：

show_all_lists.xml

DataCommunication.java

custom_row.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">


    <android.support.v7.widget.RecyclerView
        android:id="@+id/allItems"
        android:scrollbars="vertical"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

    </android.support.v7.widget.RecyclerView>

</LinearLayout>

RecycleViewAdapter.java

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/customRow"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal">

    <ImageView
        android:id="@+id/rowImage"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/ic_info_outline"/>

    <TextView
        android:id="@+id/rowTitle"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

</LinearLayout>

ShowAllListsFragment.java

import android.content.Context;
import android.support.annotation.NonNull;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;    
import java.util.List;

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

    private LayoutInflater inflater = null;
    private List<GlobalLists> results = null;

    public RecycleViewAdapter(Context context, List<GlobalLists> results){
        this.inflater = LayoutInflater.from(context);
        this.results = results;
    }    
    @NonNull
    @Override
    public RecycleViewAdapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = inflater.inflate(R.layout.custom_row, parent, false);
        ViewHolder holder = new ViewHolder(view);
        return holder;
    }

    @Override
    public void onBindViewHolder(@NonNull RecycleViewAdapter.ViewHolder holder, int position, @NonNull List<Object> payloads) {
        super.onBindViewHolder(holder, position, payloads);
        GlobalLists item = this.results.get(position);
        holder.rowTitle.setText(item.getTitle());


    }    
    @Override
    public int getItemCount() {
        return 0;
    }

    @Override
    public void onBindViewHolder(@NonNull RecycleViewAdapter.ViewHolder holder, int position) {

    }

    public class ViewHolder extends RecyclerView.ViewHolder {

        private TextView rowTitle = null;
        private ImageView rowImage = null;

        public ViewHolder(View itemView) {
            super(itemView);
            this.rowTitle = itemView.findViewById(R.id.rowTitle);
            this.rowImage = itemView.findViewById(R.id.rowImage);

        }
    }
}

MainActivity.java

import android.content.Context;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SearchView;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.List;
import java.util.Observable;
import java.util.Observer;


public class showAllLists_fragment extends android.support.v4.app.Fragment implements Observer{

    private static final String TAG = "showAllLists";           
    private RecyclerView mAllItemsView = null;
    private RecycleViewAdapter mRecycleAdapter = null;
    private DataCommunication mData = null;
    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

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


        this.mAllItemsView = (RecyclerView) view.findViewById(R.id.allItems);
        this.mRecycleAdapter = new RecycleViewAdapter(getActivity(), this.mData.getResults());
        this.mAllItemsView.setAdapter(this.mRecycleAdapter);
        this.mAllItemsView.setLayoutManager(new LinearLayoutManager(getActivity()));




        return view;
    }

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        try {
            this.mData = (DataCommunication) context;
        } catch (ClassCastException e) {
            throw new ClassCastException(context.toString()
                    + " must implement DataCommunication");
        }
    }    
    @Override
    public void onPause() {
        super.onPause();
        Log.d(TAG, "Paused!");
    }   

    @Override
    public void onResume() {
        super.onResume();
    }

    @Override
    public void update(Observable o, Object arg) {
        View root = getView();
    }
}

Answer 1

适配器类中有两个错误正确

1）。您应该在size

中返回results ArrayList数据getItemCount()

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

使用此

@Override
public int getItemCount() {
    return 0;
}

而不是这个

custom_row.xml

2）将您的wrap_content hight更改为<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/customRow" android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal">，如下面的代码

使用此

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/customRow"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal">

而不是这个

ListView

项目未显示在房间数据库的RecycleView中

1 个答案: