RecyclerView usage record

As the function & requirements of the company's own app client become more and more complex, the layout of some pages becomes more and more complex. At the suggestion of former colleagues, use RecyclerView to implement it.

demand

The general requirements are shown in the figure below. The table layout needs to be displayed through the permissions of the login user.

programme

Request the server login interface and return user information, role information, permissions, etc
The APP end assembles the data according to the permission and transfers it to the Adapter
Render view

realization

Add the following layout code to the appropriate layout of the home page layout

<androidx.recyclerview.widget.RecyclerView
                android:id="@+id/workbench_recycleview"
                android:divider="#00000000"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:background="@drawable/shape_bg"
                android:layout_marginLeft="15dp"
                android:layout_marginRight="15dp"
                android:layout_marginBottom="15dp">
</androidx.recyclerview.widget.RecyclerView>

Define the item layout, representing the layout style of each item, etc

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:gravity="center"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:gravity="center_vertical"
        android:layout_marginTop="25dp"
        android:layout_marginLeft="15dp"
        android:layout_marginRight="15dp">

        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="title"
            android:id="@+id/wb_menu_txt_title"
            android:textSize="16sp"
            android:textStyle="bold"
            android:textColor="#555555"/>

        <ImageView
            android:layout_width="36dp"
            android:layout_height="36dp"
            android:id="@+id/wb_menu_img_title"
            android:src="@mipmap/wk_ck"/>
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="20dp"
        android:orientation="vertical"
        android:layout_marginBottom="25dp"
        android:layout_marginLeft="15dp"
        android:layout_marginRight="15dp">

        <TextView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:text="This is a description"
            android:id="@+id/wb_menu_txt_info"
            android:textSize="14sp"
            android:textColor="#999999"/>
    </LinearLayout>

</LinearLayout>

The preview effect is as follows

Define the Holder class and inherit recyclerview ViewHolder

public class WorkBenchItemViewHolder extends RecyclerView.ViewHolder {

    private final TextView txtTitle;
    private final TextView txtInfo;
    private final ImageView imgTitle;

    public WorkBenchItemViewHolder(View view){
        super(view);
        txtTitle = view.findViewById(R.id.wb_menu_txt_title);
        txtInfo = view.findViewById(R.id.wb_menu_txt_info);
        imgTitle = view.findViewById(R.id.wb_menu_img_title);
    }

    public TextView getTxtInfo(){
        return this.txtInfo;
    }

    public ImageView getImg(){
        return this.imgTitle;
    }

    public TextView getTxtTitle(){
        return txtTitle;
    }
}

Define the adapter class and inherit recyclerview Adapter<WorkBenchItemViewHolder>

public class WorkBenchItemViewAdapter extends RecyclerView.Adapter<WorkBenchItemViewHolder> {

    public List<WorkbenchMenuBean> mDatas;
    private final Context mContext;
    private OnItemClickListener listener;

    public WorkBenchItemViewAdapter(Context context, List<WorkbenchMenuBean> datas) {
        this.mContext = context;
        this.mDatas = datas;
    }

    @NonNull
    @Override
    public WorkBenchItemViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        return new WorkBenchItemViewHolder(LayoutInflater.from(mContext).inflate(R.layout.home_workbench_item_view, parent,
                false));
    }

    @Override
    public void onBindViewHolder(WorkBenchItemViewHolder holder, final int position) {
        holder.getTxtTitle().setText(mDatas.get(position).getTxtTitle());
        holder.getTxtInfo().setText(mDatas.get(position).getTxtInfo());
        holder.getImg().setImageResource(mDatas.get(position).getImgTitle());

        if (listener != null) {
            holder.itemView.setOnClickListener(view -> listener.onItemClick(view, position));
        }
    }

    @Override
    public int getItemCount() {
        return mDatas.size();
    }

    //The second step is to write a public method
    public void setOnItemClickListener(OnItemClickListener listener) {
        this.listener = listener;
    }

    public interface OnItemClickListener {
        void onItemClick(View view, int position);
    }

}

Add processing logic at the corresponding page initialization page logic

Define related attributes

private RecyclerView recyclerView;
private WorkBenchItemViewAdapter adapter;
private List<WorkbenchMenuBean> listData = new ArrayList<>();

Define how to get a list

// Judging by the role obtained after login

// Here is a super account
boolean superAccount = loginInfo.isSuperAccount();
            if (superAccount) {
                listData.add(new WorkbenchMenuBean("pb", "Function 1", "Function 1 Description", R.mipmap.wk_pb));
                listData.add(new WorkbenchMenuBean("zj", "Function 2", ". . . ", R.mipmap.wk_zj));
                listData.add(new WorkbenchMenuBean("sc", "Function 3", ". . . ", R.mipmap.wk_sc));
                listData.add(new WorkbenchMenuBean("ck", "Function 4", ". . . ", R.mipmap.wk_ck));
                listData.add(new WorkbenchMenuBean("sk", "Function 5", ". . . ", R.mipmap.wk_sk));
                return;
            }

The better processing method here is that these data are also returned through the server, and the client only processes them

Call other APIs of recyclerView

// Set LayoutManager
recyclerView.setLayoutManager(new GridLayoutManager(getContext(), 2));
recyclerView.addItemDecoration(new CommonDecoration(Objects.requireNonNull(getContext())));

adapter = new WorkBenchItemViewAdapter(getContext(), listData);

// Set click event
adapter.setOnItemClickListener((view, position) -> {
  WorkbenchMenuBean workbenchMenuBean = adapter.mDatas.get(position);
  onWorkbenchMenuItemClick(workbenchMenuBean);
});
recyclerView.setAdapter(adapter);

common method

1. Get recyclerView content height

// Get recyclerView content height
int recyclerViewRealHeight = recyclerView.computeVerticalScrollRange();

We use RecyclerView The height obtained by the getHeight method is the height of the RecyclerView control, not the content height

2. Get the total number of item s in the adapter

int size = recyclerView.getAdapter().getItemCount();

3. Get the number of item s visible to recyclerView

int childCount = recyclerView.getChildCount();

4. Get the actual position of an Item

RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
//Gets its location in the adapter
int position = params.getViewLayoutPosition();

// This way is also OK
int position = recyclerView.getChildAdapterPosition(view);

5. Get the View of the corresponding Item according to the position. It should be noted that if the View corresponding to the current position is not visible, the obtained View is null.

// llm is the corresponding LayoutManager
View itemView = llm.findViewByPosition(position);

6. Gets the position of the first visible Item

int firstPosition = ((LinearLayoutManager)recyclerView.getLayoutManager()).findFirstVisibleItemPosition();

// In this way, you can also get
View childFirst = recyclerView.getChildAt(0);
RecyclerView.LayoutParams paramsFirst = (RecyclerView.LayoutParams) childFirst.getLayoutParams();
int firstPosition1 = paramsFirst.getViewLayoutPosition();

7. Gets the position of the first fully visible Item

int firstCompletelyVisibleItemPosition = ((LinearLayoutManager)recyclerView.getLayoutManager()).findFirstCompletelyVisibleItemPosition();

8. Gets the position of the last visible Item

int lastPosition = ((LinearLayoutManager)recyclerView.getLayoutManager()).findLastVisibleItemPosition();

// In this way, you can also get
int childCount = recyclerView.getChildCount();
View childLast = recyclerView.getChildAt(childCount - 1);
RecyclerView.LayoutParams paramsLast = (RecyclerView.LayoutParams) childLast.getLayoutParams();
int lastPosition1 = paramsLast.getViewLayoutPosition();

9. Gets the position of the last fully visible Item

int lastCompletelyVisibleItemPosition = ((LinearLayoutManager)parent.getLayoutManager()

reference material

Summary of common methods of RecyclerView

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license agreement

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Added by drunkencelt on Tue, 01 Mar 2022 14:55:35 +0200

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RecyclerView usage record

RecyclerView usage record

demand

programme

realization

common method

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