Android RecyclerView V7 framework and Diffutil optimization method
Android RecyclerView V7 framework and Diffutil optimization method
When developing Android applications, RecyclerView is a very common UI component to display a lot of data lists.However, when the amount of data is large or frequently updated, RecyclerView may have performance problems.To solve this problem, Android provides the RecyclerView V7 framework and Diffutil tools to optimize the performance of RecyclerView.
1. Optimization of Recyclerview V7 framework
1. Use ViewHolder mode: The ViewHolder mode uses the recycling and reuse mechanism of RecyclerView, reducing the number of layouts and destruction, and increasing the smoothness of sliding.The ViewHolder mode needs to customize a class that inherits from the RecyclerView.ViewHolder to save view references in Item.
Example code:
public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder> {
// Custom RecyclerView.Viewholder subclass
public static class MyViewHolder extends RecyclerView.ViewHolder {
// View reference in item
TextView textView;
public MyViewHolder(View itemView) {
super(itemView);
textView = itemView.findViewById(R.id.text_view);
}
}
// Data to be displayed
private List<String> dataList;
public MyAdapter(List<String> dataList) {
this.dataList = dataList;
}
// Create viewholder
@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_layout, parent, false);
return new MyViewHolder(itemView);
}
// Bind data to viewholder
@Override
public void onBindViewHolder(MyViewHolder holder, int position) {
String data = dataList.get(position);
holder.textView.setText(data);
}
// Get the length of the data list
@Override
public int getItemCount() {
return dataList.size();
}
}
2. Use the segmentation line and grid layout: RecyclerView provides the `adDItemDecoration ()` method to add the division line, which can customize the style and dimension of the segmentation line by customizing the ItemDecorax class.In addition, the grid layout can be achieved through GridLayoutManager to display a more complex interface.
Example code:
// Add the segmentation line
RecyclerView recyclerView = findViewById(R.id.recycler_view);
recyclerView.addItemDecoration(new DividerItemDecoration(this, LinearLayoutManager.VERTICAL));
// Set the grid layout
recyclerView.setLayoutManager(new GridLayoutManager(this, 2));
3. Use animation: RecyclerView provides the `SetItemanimator () method, which can add animation effects to operations such as insertion, removal, refreshing, etc.When customized animations, you can inherit the RecyclerView.itemanimator class, and achieve your own animation effect as needed.
Example code:
// Set animation
recyclerView.setItemAnimator(new DefaultItemAnimator());
2. Optimization of Diffutil
DiffUtil is a practical tool class to calculate the difference between the RecyclerView dataset. It can efficiently calculate the difference in the data set and make targeted updates based on the difference.
The use steps of Diffutil are as follows:
1. Create a callback class inherited from Difffutil.Callback and rewrite the following four methods:
-` GetoldListSize () `: Back to the size of the old data set
-` GetnewListSize () `: Back to the size of the new data set
-`oremsthesame () `: Determine whether the two ites represent the same object, in this method, you need to compare the unique identifier of ITEM
-`AreContentSthesame ()`: Determine whether the data content of the two items is the same
Example code:
public class MyDiffUtilCallback extends DiffUtil.Callback {
private List<String> oldDataList;
private List<String> newDataList;
public MyDiffUtilCallback(List<String> oldDataList, List<String> newDataList) {
this.oldDataList = oldDataList;
this.newDataList = newDataList;
}
@Override
public int getOldListSize() {
return oldDataList.size();
}
@Override
public int getNewListSize() {
return newDataList.size();
}
@Override
public boolean areItemsTheSame(int oldItemPosition, int newItemPosition) {
String oldData = oldDataList.get(oldItemPosition);
String newData = newDataList.get(newItemPosition);
return oldData.equals(newData);
}
@Override
public boolean areContentsTheSame(int oldItemPosition, int newItemPosition) {
String oldData = oldDataList.get(oldItemPosition);
String newData = newDataList.get(newItemPosition);
return oldData.equals(newData);
}
}
2. When updating the dataset, use the static method of Diffutil to calculate the difference in the data, and use the application differences of the `notifydatasetchangataTChaanged () method through RecyclerView.adapter.
Example code:
List <string> Olddatalist = ... // Old data set
List <string> newdatalist = ... // New data set
MyDiffUtilCallback diffUtilCallback = new MyDiffUtilCallback(oldDataList, newDataList);
DiffUtil.DiffResult diffResult = DiffUtil.calculateDiff(diffUtilCallback);
// Application differences
oldDataList.clear();
oldDataList.addAll(newDataList);
diffResult.dispatchUpdatesTo(adapter);
Through the above optimization methods, the performance and user experience of RecyclerView can be improved, especially when the data set is large or frequently updated.In actual development, a suitable optimization method can be selected according to specific needs.
