【Android】使RecyclerView 支持setEmptyView
16lz
2022-03-17
自定义一个RecyclerView 的子类，使其支持EmptyView机制。
public class EmptyRecyclerView extends RecyclerView { private View emptyView; final private AdapterDataObserver observer = new AdapterDataObserver() { @Override public void onChanged() { checkIfEmpty(); } @Override public void onItemRangeInserted(int positionStart, int itemCount) { checkIfEmpty(); } @Override public void onItemRangeRemoved(int positionStart, int itemCount) { checkIfEmpty(); } }; public EmptyRecyclerView(Context context) { super(context); } public EmptyRecyclerView(Context context, AttributeSet attrs) { super(context, attrs); } public EmptyRecyclerView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); } 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(Adapter adapter) { final Adapter oldAdapter = getAdapter(); if (oldAdapter != null) { oldAdapter.unregisterAdapterDataObserver(observer); } super.setAdapter(adapter); if (adapter != null) { adapter.registerAdapterDataObserver(observer); } checkIfEmpty(); } public void setEmptyView(View emptyView) { this.emptyView = emptyView; checkIfEmpty(); if (emptyView.getParent() == null) { //如果emptyView没有父布局，则添加至当前RecyclerView的父View中 ViewParent parent = getParent(); if (parent instanceof RelativeLayout) { //相对布局 RelativeLayout.LayoutParams layoutParams = new RelativeLayout.LayoutParams( LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT); ViewGroup parentView = (ViewGroup) getParent(); layoutParams.addRule(RelativeLayout.CENTER_IN_PARENT); parentView.addView(emptyView, layoutParams); } else if (getParent() instanceof ViewGroup) { ViewGroup parentView = (ViewGroup) getParent(); parentView.addView(emptyView); } } }}如果你使用的IRecyclerView，那么如果要支持setEmptyView，可以参照如下代码：
IRecyclerView项目地址在这里，IRecyclerView on GitHUb
package com.xxx;import android.content.Context;import android.util.AttributeSet;import android.view.View;import android.view.ViewGroup;import android.view.ViewParent;import android.widget.RelativeLayout;import com.aspsine.irecyclerview.IRecyclerView;/** * Created by Administrator on 2016/7/28. */public class EmptyRecyclerView extends IRecyclerView { private View emptyView; final private AdapterDataObserver observer = new AdapterDataObserver() { @Override public void onChanged() { checkIfEmpty(); } @Override public void onItemRangeInserted(int positionStart, int itemCount) { checkIfEmpty(); } @Override public void onItemRangeRemoved(int positionStart, int itemCount) { checkIfEmpty(); } }; public EmptyRecyclerView(Context context) { super(context); } public EmptyRecyclerView(Context context, AttributeSet attrs) { super(context, attrs); } public EmptyRecyclerView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); } void checkIfEmpty() { Adapter adapter = getMyAdapter(); if (emptyView != null && adapter != null) { final boolean emptyViewVisible = adapter.getItemCount() == 0; emptyView.setVisibility(emptyViewVisible ? VISIBLE : GONE); setVisibility(emptyViewVisible ? GONE : VISIBLE); } } /** * 对getIAdapter做些简单处理，避免跟getAdapter重名，叫getMyAdapter。 * * @return */ private Adapter getMyAdapter() { Adapter adapter = null; try { adapter = getIAdapter(); } catch (Exception e) { } return adapter; } @Override public void setIAdapter(Adapter adapter) { final Adapter oldAdapter = getMyAdapter(); if (oldAdapter != null) { oldAdapter.unregisterAdapterDataObserver(observer); } super.setIAdapter(adapter); if (adapter != null) { adapter.registerAdapterDataObserver(observer); } checkIfEmpty(); } public void setEmptyView(View emptyView) { this.emptyView = emptyView; checkIfEmpty(); if (emptyView.getParent() == null) { //如果emptyView没有父布局，则添加至当前RecyclerView的父View中 ViewParent parent = getParent(); if (parent instanceof RelativeLayout) { //相对布局 RelativeLayout.LayoutParams layoutParams = new RelativeLayout.LayoutParams( LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT); ViewGroup parentView = (ViewGroup) getParent(); layoutParams.addRule(RelativeLayout.CENTER_IN_PARENT); parentView.addView(emptyView, layoutParams); } else if (getParent() instanceof ViewGroup) { ViewGroup parentView = (ViewGroup) getParent(); parentView.addView(emptyView); } } }}更多相关文章
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