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
1、页面对应的xml代码如下：
<?xml version="1.0" encoding="utf-8"?> <layout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools"> <data> <variable name="presenter" type="com.example.customview.ui.RecyclerViewActivity.Presenter" /> </data> <LinearLayout android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" tools:context=".ui.RecyclerViewActivity"> <androidx.constraintlayout.widget.ConstraintLayout android:layout_width="match_parent" android:layout_height="wrap_content"> <Button android:id="@+id/btn_reset" android:layout_width="wrap_content" android:layout_height="wrap_content" android:onClick="@{(view)->presenter.onClick(view)}" android:text="重置" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" /> <Button android:id="@+id/btn_refresh_all" android:layout_width="wrap_content" android:layout_height="wrap_content" android:onClick="@{(view)->presenter.onClick(view)}" android:text="全部刷新" app:layout_constraintStart_toEndOf="@id/btn_reset" app:layout_constraintTop_toTopOf="parent" /> <Button android:id="@+id/btn_refresh_2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:onClick="@{(view)->presenter.onClick(view)}" android:text="刷新第2条" app:layout_constraintStart_toEndOf="@id/btn_refresh_all" app:layout_constraintTop_toTopOf="parent" /> <Button android:id="@+id/btn_refresh_234" android:layout_width="wrap_content" android:layout_height="wrap_content" android:onClick="@{(view)->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" /> <Button android:id="@+id/btn_part_refresh_2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:onClick="@{(view)->presenter.onClick(view)}" android:text="局部刷新第2条" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@id/btn_reset" /> <Button android:id="@+id/btn_part_refresh_234" android:layout_width="wrap_content" android:layout_height="wrap_content" android:onClick="@{(view)->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" /> <Button android:id="@+id/btn_insert_1_1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:onClick="@{(view)->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" /> <Button android:id="@+id/btn_insert_3_2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:onClick="@{(view)->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" /> <Button android:id="@+id/btn_move_2_4" android:layout_width="wrap_content" android:layout_height="wrap_content" android:onClick="@{(view)->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" /> <Button android:id="@+id/btn_remove_2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:onClick="@{(view)->presenter.onClick(view)}" android:text="删除第2条" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@id/btn_move_2_4" /> <Button android:id="@+id/btn_remove_234" android:layout_width="wrap_content" android:layout_height="wrap_content" android:onClick="@{(view)->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" /> </androidx.constraintlayout.widget.ConstraintLayout> <androidx.recyclerview.widget.RecyclerView android:id="@+id/rv_list" android:layout_width="match_parent" android:layout_height="wrap_content" android:overScrollMode="never" android:scrollbars="none" /> </LinearLayout> </layout>
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<NotifyDataAdapter.NotifyDataViewHolder> { private List<NotifyModel> notifyModels = new ArrayList<>(); public NotifyDataAdapter(List<NotifyModel> notifyModels) { this.notifyModels = notifyModels; } @NonNull @Override public 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); } @Override public void onBindViewHolder(@NonNull NotifyDataViewHolder holder, int position) { Log.i("TAG", "onBindViewHolder:两个参数 " + position); holder.bindData(position); } @Override public void onBindViewHolder(@NonNull NotifyDataViewHolder holder, int position, @NonNull List<Object> 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()); } } } } @Override public int getItemCount() { Log.i("TAG", "getItemCount: " + notifyModels.size()); return notifyModels.size(); } @Override public 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<NotifyModel> notifyModels = new ArrayList<>(); @Override protected 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 } }
