Android RecyclerView的notify方法和动画的刷新详解
创始人
2024-06-01 12:19:11
0次

前些天发现了一个蛮有意思的人工智能学习网站,8个字形容一下"通俗易懂,风趣幽默",感觉非常有意思,忍不住分享一下给大家。
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前言:

本篇讲解了RecyclerView关于通知列表刷新的常用的notify方法。和RecyclerView动画的简单详解。

首先看下效果图

在这里插入图片描述

1、页面对应的xml代码如下:


presenter.onClick(view)}"android:text="重置"app:layout_constraintStart_toStartOf="parent"app:layout_constraintTop_toTopOf="parent" />presenter.onClick(view)}"android:text="全部刷新"app:layout_constraintStart_toEndOf="@id/btn_reset"app:layout_constraintTop_toTopOf="parent" />presenter.onClick(view)}"android:text="刷新第2条"app:layout_constraintStart_toEndOf="@id/btn_refresh_all"app:layout_constraintTop_toTopOf="parent" />presenter.onClick(view)}"android:text="刷新第2,3,4条"app:layout_constraintStart_toEndOf="@id/btn_refresh_2"app:layout_constraintTop_toTopOf="parent" />presenter.onClick(view)}"android:text="局部刷新第2条"app:layout_constraintStart_toStartOf="parent"app:layout_constraintTop_toBottomOf="@id/btn_reset" />presenter.onClick(view)}"android:text="局部刷新第2,3,4条"app:layout_constraintStart_toEndOf="@+id/btn_part_refresh_2"app:layout_constraintTop_toBottomOf="@id/btn_reset" />presenter.onClick(view)}"android:text="位置1插入一条"app:layout_constraintStart_toStartOf="parent"app:layout_constraintTop_toBottomOf="@id/btn_part_refresh_234" />presenter.onClick(view)}"android:text="位置3插入两条"app:layout_constraintStart_toEndOf="@id/btn_insert_1_1"app:layout_constraintTop_toBottomOf="@id/btn_part_refresh_234" />presenter.onClick(view)}"android:text="2移到4(都指的是索引)"app:layout_constraintStart_toEndOf="@id/btn_insert_3_2"app:layout_constraintTop_toBottomOf="@id/btn_part_refresh_234" />presenter.onClick(view)}"android:text="删除第2条"app:layout_constraintStart_toStartOf="parent"app:layout_constraintTop_toBottomOf="@id/btn_move_2_4" />presenter.onClick(view)}"android:text="删除第2,3,4条"app:layout_constraintStart_toEndOf="@id/btn_remove_2"app:layout_constraintTop_toBottomOf="@id/btn_move_2_4" />

2、对应的适配器代码如下

/*** @Author: ly* @Date: 2023/3/9* @Description: 适配器*/
public class NotifyDataAdapter extends RecyclerView.Adapter {private List notifyModels = new ArrayList<>();public NotifyDataAdapter(List notifyModels) {this.notifyModels = notifyModels;}@NonNull@Overridepublic NotifyDataViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {ItemNotifyDataBinding binding = DataBindingUtil.inflate(LayoutInflater.from(parent.getContext()), R.layout.item_notify_data, parent, false);Log.i("TAG", "onCreateViewHolder: ");return new NotifyDataViewHolder(binding);}@Overridepublic void onBindViewHolder(@NonNull NotifyDataViewHolder holder, int position) {Log.i("TAG", "onBindViewHolder:两个参数 " + position);holder.bindData(position);}@Overridepublic void onBindViewHolder(@NonNull NotifyDataViewHolder holder, int position, @NonNull List payloads) {Log.i("TAG", "onBindViewHolder:三个参数 " + position);if (payloads.isEmpty()) {/** payloads为空说明不需要局部刷新,走原有的onBindViewHolder(holder, position) */onBindViewHolder(holder, position);} else {for (Object o : payloads) {String payload = (String) o;if ("title".equals(payload)) { /** 只刷新title字段 */holder.binding.tvTitle.setText(notifyModels.get(position).getTitle());} else if ("content".equals(payload)) {/** 只刷新content字段 */holder.binding.tvContent.setText(notifyModels.get(position).getContent());}}}}@Overridepublic int getItemCount() {Log.i("TAG", "getItemCount: " + notifyModels.size());return notifyModels.size();}@Overridepublic int getItemViewType(int position) {Log.i("TAG", "getItemViewType: " + position);return super.getItemViewType(position);}public class NotifyDataViewHolder extends RecyclerView.ViewHolder {ItemNotifyDataBinding binding;public NotifyDataViewHolder(@NonNull ItemNotifyDataBinding itemView) {super(itemView.getRoot());binding = itemView;}public void bindData(int position) {binding.setModel(notifyModels.get(position));}}
}
 

Activity对应的代码如下,关于notify方法已经在注释中给出:

/*** @Author: ly* @Date: 2023/3/11* @Description: RecyclerView常用notify方法*/
public class RecyclerViewActivity extends AppCompatActivity {private ActivityRecyclerViewBinding binding;private NotifyDataAdapter adapter;private List notifyModels = new ArrayList<>();@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);binding = DataBindingUtil.setContentView(this, R.layout.activity_recycler_view);binding.setPresenter(new Presenter());initData();
//        binding.rvList.setItemAnimator(null);//去掉默认动画
//        binding.rvList.setItemAnimator(new SlideInLeftAnimator());binding.rvList.setLayoutManager(new LinearLayoutManager(this));adapter = new NotifyDataAdapter(notifyModels);binding.rvList.setAdapter(adapter);}private void initData() {notifyModels.clear();for (int i = 0; i < 5; i++) {notifyModels.add(new NotifyModel("第" + i + "个标题", "第" + i + "条详细内容,详细的信息"));}}public class Presenter {public void onClick(View view) {if (view == binding.btnReset) {reset();} else if (view == binding.btnRefreshAll) {notifyAllData();} else if (view == binding.btnRefresh2) {notify_2();} else if (view == binding.btnRefresh234) {notify_234();} else if (view == binding.btnPartRefresh2) {notifyPart_2();} else if (view == binding.btnPartRefresh234) {notifyPart_234();} else if (view == binding.btnInsert11) {insert_1_1();} else if (view == binding.btnInsert32) {insert_3_2();} else if (view == binding.btnMove24) {move_2_4();} else if (view == binding.btnRemove2) {remove2();} else if (view == binding.btnRemove234) {remove234();}}}/*** 删除索引为2,3,4条的数据*/private void remove234() {for (NotifyModel model : notifyModels) {model.setTitle("remove234" + model.getTitle());model.setContent("remove234" + model.getContent());}NotifyModel model2 = notifyModels.get(2);NotifyModel model3 = notifyModels.get(3);NotifyModel model4 = notifyModels.get(4);notifyModels.remove(model2);notifyModels.remove(model3);notifyModels.remove(model4);//notifyItemRangeRemoved(int positionStart, int itemCount)//从positionStart位置,itemCount数量的数据进行删除adapter.notifyItemRangeRemoved(2, 3);}/*** 删除索引为2的条目数据*/private void remove2() {for (NotifyModel model : notifyModels) {model.setTitle("remove2" + model.getTitle());model.setContent("remove2" + model.getContent());}notifyModels.remove(2);//notifyItemRemoved(int position):列表position位置移除一条数据时调用。adapter.notifyItemRemoved(2);}/*** 2的位置移动到4*/private void move_2_4() {for (NotifyModel model : notifyModels) {model.setTitle("move_2_4" + model.getTitle());model.setContent("move_2_4" + model.getContent());}//notifyItemMoved(int fromPosition, int toPosition):将条目下标为fromPosition的位置//移动到toPosition位置时调用。adapter.notifyItemMoved(2, 4);}/*** 在索引位置为3的位置,添加了两条数据*/private void insert_3_2() {for (NotifyModel model : notifyModels) {model.setTitle("insert_3_2" + model.getTitle());model.setContent("insert_3_2" + model.getContent());}NotifyModel model = new NotifyModel("insert_3_2 add 3", "insert_3_2 add 3");notifyModels.add(3, model);//在索引为3的位置,添加了一条数据NotifyModel model1 = new NotifyModel("insert_3_2 add 4", "insert_3_2 add 4");notifyModels.add(4, model1);//在索引为3的位置,添加了一条数据//notifyItemRangeInserted(int positionStart, int itemCount)//从指定的位置开始刷新,添加itemCount个数据adapter.notifyItemRangeInserted(3, 2);}/*** 索引为1处,插入1条数据*/private void insert_1_1() {for (NotifyModel model : notifyModels) {model.setTitle("insert_1_1" + model.getTitle());model.setContent("insert_1_1" + model.getContent());}NotifyModel model = new NotifyModel("insert_1_1 add", "insert_1_1 add");notifyModels.add(1, model);//在索引为1的位置,添加了一条数据//notifyItemInserted(position):在position位置添加一条数据adapter.notifyItemInserted(1);}/*** 局部更新,下标为2开始的三条数据(包含2 那么其实就是2,3,4)*/private void notifyPart_234() {for (NotifyModel model : notifyModels) {model.setTitle("notifyPart_234" + model.getTitle());model.setContent("notifyPart_234" + model.getContent());}NotifyModel model = new NotifyModel("notifyPart_234 add", "notifyPart_234 add");notifyModels.add(model);// notifyItemRangeChanged(int positionStart, int itemCount,//                @Nullable Object payload):从指定的位置开始刷新,指定个item//payload用来标记需要局部刷新的部分。adapter.notifyItemRangeChanged(2, 3, "content");}/*** 局部更新,更新下标索引为2的条目,刷新其中的一个字段*/private void notifyPart_2() {for (NotifyModel model : notifyModels) {model.setTitle("notifyPart_2" + model.getTitle());model.setContent("notifyPart_2" + model.getContent());}NotifyModel model = new NotifyModel("notifyPart_2 add", "notifyPart_2 add");notifyModels.add(model);//notifyItemChanged(int position, @Nullable Object payload):刷新指定位置//payload用来标记需要局部刷新的部分。adapter.notifyItemChanged(2, "title");//只局部刷新下标为2的条目数据 数据又新增了一条,这时也会被加载出来。}/*** 刷新下标为2开始的三条数据(包含2 那么其实就是2,3,4)*/private void notify_234() {for (NotifyModel model : notifyModels) {model.setTitle("notify_2" + model.getTitle());model.setContent("notify_2" + model.getContent());}NotifyModel model = new NotifyModel("notify_2 add", "notify_2 add");notifyModels.add(model);//notifyItemRangeChanged(int positionStart, int itemCount):从指定的位置开始刷新,指定个item//item传1等价于notifyItemChanged(position)adapter.notifyItemRangeChanged(2, 3);}/*** 刷新下标位置为2的条目数据*/private void notify_2() {for (NotifyModel model : notifyModels) {model.setTitle("notify_2" + model.getTitle());model.setContent("notify_2" + model.getContent());}NotifyModel model = new NotifyModel("notify_2 add", "notify_2 add");notifyModels.add(model);//notifyItemChanged(position):刷新指定位置adapter.notifyItemChanged(2);//只刷新下标为2的条目数据 数据又新增了一条,这时也会被加载出来。}/*** 重置*/private void reset() {initData();adapter.notifyDataSetChanged();}/*** 刷新全部*/public void notifyAllData() {for (NotifyModel model : notifyModels) {model.setTitle("notifyAll" + model.getTitle());model.setContent("notifyAll" + model.getContent());}NotifyModel model = new NotifyModel("notifyAll add", "notifyAll add");notifyModels.add(model);adapter.notifyDataSetChanged();//刷新全部item}}

下面是调用不同的notify方法适配器执行的方法顺序如下:
对应上文
1、执行notifyAllData(),实际调用的是 notifyDataSetChanged 刷新全部,适配器执行方法如下

getItemCount: 6
getItemCount: 6
getItemCount: 6
getItemViewType: 0
onBindViewHolder:三个参数
onBindViewHolder:两个参数
getItemCount: 6
getItemViewType: 1
onBindViewHolder:三个参数
onBindViewHolder:两个参数
getItemCount: 6
getItemViewType: 2
onBindViewHolder:三个参数
onBindViewHolder:两个参数
getItemCount: 6
getItemViewType: 3
onBindViewHolder:三个参数
onBindViewHolder:两个参数
getItemCount: 6
getItemViewType: 4
onBindViewHolder:三个参数
onBindViewHolder:两个参数
getItemCount: 6
getItemViewType: 5
onCreateViewHolder: 
onBindViewHolder:三个参数
onBindViewHolder:两个参数
getItemCount: 6
getItemCount: 6
getItemViewType: 0
getItemCount: 6
getItemViewType: 1
getItemCount: 6
getItemViewType: 2
getItemCount: 6
getItemViewType: 3
getItemCount: 6
getItemViewType: 4
getItemCount: 6
getItemViewType: 5

2、执行notify_2(),实际调用的是 notifyItemChanged(2),适配器执行方法如下

getItemCount: 6
getItemCount: 6
getItemViewType: 0
getItemCount: 6
getItemViewType: 1
getItemCount: 6
getItemViewType: 2
onCreateViewHolder: 
onBindViewHolder:三个参数
onBindViewHolder:两个参数
getItemCount: 6
getItemViewType: 3
getItemCount: 6
getItemViewType: 4
getItemCount: 6
getItemViewType: 5
onCreateViewHolder: 
onBindViewHolder:三个参数
onBindViewHolder:两个参数
getItemCount: 6
getItemCount: 6
getItemViewType: 0
getItemCount: 6
getItemViewType: 1
getItemCount: 6
getItemViewType: 2
getItemCount: 6
getItemViewType: 3
getItemCount: 6
getItemViewType: 4
getItemCount: 6
getItemViewType: 5

3、执行notify_234(),实际调用的是 notifyItemRangeChanged(2, 3);,适配器执行方法如下

 getItemCount: 6getItemCount: 6getItemViewType: 0getItemCount: 6getItemViewType: 1getItemCount: 6getItemViewType: 2onCreateViewHolder: onBindViewHolder:三个参数onBindViewHolder:两个参数getItemCount: 6getItemViewType: 3onCreateViewHolder: onBindViewHolder:三个参数onBindViewHolder:两个参数getItemCount: 6getItemViewType: 4onCreateViewHolder: onBindViewHolder:三个参数onBindViewHolder:两个参数getItemCount: 6getItemViewType: 5onCreateViewHolder: onBindViewHolder:三个参数onBindViewHolder:两个参数getItemCount: 6getItemCount: 6getItemViewType: 0getItemCount: 6getItemViewType: 1getItemCount: 6getItemViewType: 2getItemCount: 6getItemViewType: 3getItemCount: 6getItemViewType: 4getItemCount: 6getItemViewType: 5

4、执行notifyPart_2(),实际调用的是 notifyItemChanged(2, “title”);,适配器执行方法如下

getItemCount: 6
getItemCount: 6
getItemViewType: 0
getItemCount: 6
getItemViewType: 1
getItemCount: 6
getItemViewType: 2
onBindViewHolder:三个参数
getItemCount: 6
getItemViewType: 3
getItemCount: 6
getItemViewType: 4
getItemCount: 6
getItemViewType: 5
onCreateViewHolder: 
onBindViewHolder:三个参数
onBindViewHolder:两个参数
getItemCount: 6
getItemCount: 6
getItemViewType: 0
getItemCount: 6
getItemViewType: 1
getItemCount: 6
getItemViewType: 2
getItemCount: 6
getItemViewType: 3
getItemCount: 6
getItemViewType: 4
getItemCount: 6
getItemViewType: 5

5、执行notifyPart_234(),实际调用的是notifyItemRangeChanged(2, 3, “content”);,适配器执行方法如下

getItemCount: 6
getItemCount: 6
getItemViewType: 0
getItemCount: 6
getItemViewType: 1
getItemCount: 6
getItemViewType: 2
onBindViewHolder:三个参数
getItemCount: 6
getItemViewType: 3
onBindViewHolder:三个参数
getItemCount: 6
getItemViewType: 4
onBindViewHolder:三个参数
getItemCount: 6
getItemViewType: 5
onCreateViewHolder: 
onBindViewHolder:三个参数
onBindViewHolder:两个参数
getItemCount: 6
getItemCount: 6
getItemViewType: 0
getItemCount: 6
getItemViewType: 1
getItemCount: 6
getItemViewType: 2
getItemCount: 6
getItemViewType: 3
getItemCount: 6
getItemViewType: 4
getItemCount: 6
getItemViewType: 5

6、执行insert_1_1(),实际调用的是notifyItemInserted(1);,适配器执行方法如下

getItemCount: 6
getItemCount: 6
getItemViewType: 0
getItemCount: 6
getItemViewType: 1
onCreateViewHolder: 
onBindViewHolder:三个参数
onBindViewHolder:两个参数
getItemCount: 6
getItemViewType: 2
getItemCount: 6
getItemViewType: 3
getItemCount: 6
getItemViewType: 4
getItemCount: 6
getItemViewType: 5
getItemCount: 6
getItemCount: 6
getItemViewType: 0
getItemCount: 6
getItemViewType: 1
getItemCount: 6
getItemViewType: 2
getItemCount: 6
getItemViewType: 3
getItemCount: 6
getItemViewType: 4
getItemCount: 6
getItemViewType: 5

7、执行insert_3_2(),实际调用的是notifyItemRangeInserted(3, 2);,适配器执行方法如下

getItemCount: 7
getItemCount: 7
getItemViewType: 0
getItemCount: 7
getItemViewType: 1
getItemCount: 7
getItemViewType: 2
getItemCount: 7
getItemViewType: 3
onCreateViewHolder: 
onBindViewHolder:三个参数
onBindViewHolder:两个参数
getItemCount: 7
getItemViewType: 4
onCreateViewHolder: 
onBindViewHolder:三个参数
onBindViewHolder:两个参数
getItemCount: 7
getItemViewType: 5
getItemCount: 7
getItemViewType: 6
getItemCount: 7
getItemCount: 7
getItemViewType: 0
getItemCount: 7
getItemViewType: 1
getItemCount: 7
getItemViewType: 2
getItemCount: 7
getItemViewType: 3
getItemCount: 7
getItemViewType: 4
getItemCount: 7
getItemViewType: 5
getItemCount: 7
getItemViewType: 6

7、执行move_2_4(),实际调用的是notifyItemMoved(2, 4);,适配器执行方法如下

getItemCount: 5
getItemCount: 5
getItemViewType: 0
getItemCount: 5
getItemViewType: 1
getItemCount: 5
getItemViewType: 2
getItemCount: 5
getItemViewType: 3
getItemCount: 5
getItemViewType: 4
getItemCount: 5
getItemCount: 5
getItemViewType: 0
getItemCount: 5
getItemViewType: 1
getItemCount: 5
getItemViewType: 2
getItemCount: 5
getItemViewType: 3
getItemCount: 5
getItemViewType: 4

8、执行remove2(),实际调用的是notifyItemRemoved(2);,适配器执行方法如下

getItemCount: 4
getItemCount: 4
getItemViewType: 0
getItemCount: 4
getItemViewType: 1
getItemCount: 4
getItemViewType: 2
getItemCount: 4
getItemViewType: 3
getItemCount: 4
getItemCount: 4
getItemViewType: 0
getItemCount: 4
getItemViewType: 1
getItemCount: 4
getItemViewType: 2
getItemCount: 4
getItemViewType: 3

9、执行remove234(),实际调用的是notifyItemRangeRemoved(2, 3);,适配器执行方法如下

getItemCount: 2
getItemCount: 2
getItemViewType: 0
getItemCount: 2
getItemViewType: 1
getItemCount: 2
getItemCount: 2
getItemViewType: 0
getItemCount: 2
getItemViewType: 1

RecyclerView动画可以选择使用三方库

Github地址

https://github.com/wasabeef/recyclerview-animators

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