关于RecyclerView（二）设置EmptyView

1. 首先重写一个RecyclerView类

package com.onepilltest.others;

import android.content.Context;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v7.widget.RecyclerView;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;

public class MyRecyclerView extends RecyclerView {

    private View emptyView;
    private static final String TAG = "EmptyRecyclerView";


    //数据监听者
    final private AdapterDataObserver adapterDataObserver = new AdapterDataObserver() {
        @Override
        public void onChanged() {
            checkIfEmpty();
        }

        @Override
        public void onItemRangeInserted(int positionStart, int itemCount) {
            Log.i(TAG, "onItemRangeInserted" + itemCount);
            checkIfEmpty();
        }

        @Override
        public void onItemRangeRemoved(int positionStart, int itemCount) {
            checkIfEmpty();
        }
    };

    private void checkIfEmpty() {
        if (emptyView != null && getAdapter() != null) {
            final boolean emptyViewVisible =
                    getAdapter().getItemCount() == 0;
            emptyView.setVisibility(emptyViewVisible ? VISIBLE : GONE);
            setVisibility(emptyViewVisible ? GONE : VISIBLE);
        }
    }

    @Override
    public void setAdapter(@Nullable Adapter adapter) {
        final Adapter oldAdapter = getAdapter();
        if (oldAdapter != null) {
            oldAdapter.unregisterAdapterDataObserver(adapterDataObserver);
        }
        super.setAdapter(adapter);
        if (adapter != null) {
            adapter.registerAdapterDataObserver(adapterDataObserver);
        }

        checkIfEmpty();
    }

    //设置没有内容时，提示用户的空布局
    public void setEmptyView(View emptyView) {
        this.emptyView = emptyView;
        checkIfEmpty();
    }

    public MyRecyclerView(@NonNull Context context) {
        super(context);
    }

    public MyRecyclerView(@NonNull Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }

    public MyRecyclerView(@NonNull Context context, @Nullable AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }
}

2. 然后在activity中添加一个ImageView作为数据为空时显示的图片

<!--Empty提示图-->
    <ImageView
        android:id="@+id/empty_iv"
        android:layout_margin="20dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:scaleType="centerCrop"
        android:contentDescription="@null"
        android:src="@drawable/empty"
        android:layout_centerInParent="true" />

3. 最后添加下面的代码即可
   1. 找到相应的ImageView
   2. 调用setEmptyView方法

recyclerView.setEmptyView(mEmptyView);

4. 显示

有数据：

数据为空：