Recycler View 未在相对布局中打开。没有编译错误

Question

我有一个使用相对布局的片段。在那个 XML 中，我有两个视图 - 一个 TextView 和一个 RecyclerView

没有编译错误，但是当运行应用程序时，RecyclerView 中的卡片不会显示：

这是片段代码：

package com.hfad.bitsandpizzas;


import android.content.Intent;
import android.os.Bundle;
import android.app.Fragment;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.RelativeLayout;

public class TopFragment extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        RelativeLayout layout = (RelativeLayout)inflater.inflate(R.layout.fragment_top, container, false);
        RecyclerView pizzaRecycler = (RecyclerView)layout.findViewById(R.id.pizza_recycler);
        String[] pizzaNames = new String[2];
        for(int i=0; i<2; i++){
            pizzaNames[i]=Pizza.pizzas[i].getName();
        }
        int[] pizzaImages = new int[2];
        for(int i=0; i<2; i++){
            pizzaImages[i]=Pizza.pizzas[i].getImageResourceId();
        }
        GridLayoutManager layoutManager = new GridLayoutManager(getActivity(),2);
        pizzaRecycler.setLayoutManager(layoutManager);

        CaptionedImagesAdapter adapter = new CaptionedImagesAdapter(pizzaNames, pizzaImages);
        pizzaRecycler.setAdapter(adapter);

        adapter.setListener(new CaptionedImagesAdapter.Listener() {
            @Override
            public void onClick(int position){
                Intent intent = new Intent(getActivity(), PizzaDetailActivity.class);
                intent.putExtra(PizzaDetailActivity.EXTRA_PIZZANO, position);
                getActivity().startActivity(intent);
            }
        });
        return layout;
    }


}

布局如下XML:

<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">


<TextView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:text="@string/title_top"
    android:id="@+id/top_text"/>

<android.support.v7.widget.RecyclerView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:id="@+id/pizza_recycler"
    android:layout_below="@+id/top_text"
    android:layout_marginTop="10dp"
    android:scrollbars="vertical"/>

这里是适配器代码：

package com.hfad.bitsandpizzas;

import android.graphics.drawable.Drawable;
import android.support.v7.widget.CardView;
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;

public class CaptionedImagesAdapter extends RecyclerView.Adapter<CaptionedImagesAdapter.ViewHolder> {
    private String[] captions;
    private int[] imageIds;
    private Listener listener;

    public CaptionedImagesAdapter(String[] captions, int[] imageIds){
        this.captions = captions;
        this.imageIds = imageIds;
    }

    public static class ViewHolder extends RecyclerView.ViewHolder {
        private CardView cardView;
        public ViewHolder(CardView v){
            super(v);
            cardView=v;
        }

    }

    @Override
    public CaptionedImagesAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

        CardView cv = (CardView) LayoutInflater.from(parent.getContext()).inflate(R.layout.card_captioned_image, parent, false);
        return new ViewHolder(cv);
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, final int position) {
        CardView cardView = holder.cardView;
        ImageView imageView = (ImageView)cardView.findViewById(R.id.info_image);
        Drawable drawable = cardView.getResources().getDrawable(imageIds[position]);
        imageView.setImageDrawable(drawable);
        imageView.setContentDescription(captions[position]);
        TextView textView = (TextView)cardView.findViewById(R.id.info_text);
        textView.setText(captions[position]);

        cardView.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v){
                if(listener!=null){
                    listener.onClick(position);
                }
            }
        });

    }

    @Override
    public int getItemCount() {
        return captions.length;
    }

    public static interface Listener{
        public void onClick(int position);
    }

    public void setListener(Listener listener){
        this.listener=listener;
    }
}

谢谢！

Answer 1

布局中 TextView 的高度设置为 "match_parent"。该片段也设置为 match_parent，并且由于可能 activity 的设置方式相同，这意味着您的 TextView 将占据整个屏幕。

我导入了您的代码，对绕过丢失的对象进行了最小的更改，我能够重现该问题。

通过将 TextView 的高度更改为 "wrap_content"，您将为 RecyclerView 腾出空间。

Recycler View 未在相对布局中打开。没有编译错误

Recycler View not opening within a Relative Layout. No compilation errors

android-layout

android-fragments

material-design

android-recyclerview