android infinite/endless scroll

infinite/endless scroll 이란?

페이지 이동없이 스크롤을 내리면 다음 페이지의 내용을 불러오는 것을 의미한다. 즉, 무한스크롤이다.

 

예제를 통해 실습해본 후 내 프로젝트에 맞게 변경했다.

서버에서 받아온 데이터가 100개라고 가정했을 때 100개를 담는 리스트를 하나를 할당한 후 스크롤 이벤트가 발생할때 

10개의 데이터를 불러온다.

 

 

테스트 예제 

activity_main.xml

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

    <androidx.recyclerview.widget.RecyclerView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/recyclerview"/>

</LinearLayout>

 

 

item_recycler.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:cardElevation="8dp"
    app:cardUseCompatPadding="true">


    <TextView
        android:id="@+id/tvItem"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:padding="16dp"
        android:text="Item X" />

</androidx.cardview.widget.CardView>

 

 

 

item_loading.xml

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

    <ProgressBar
        android:id="@+id/progressBar"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:indeterminate="true"
        android:paddingLeft="8dp"
        android:paddingRight="8dp"
        />

</LinearLayout>

 

 

RecyclerViewAdapter

public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {

    private final int VIEW_TYPE_ITEM = 0;
    private final int VIEW_TYPE_LOADING = 1;

    public List<String> mItemList;


    public RecyclerViewAdapter(List<String> itemList) {
        mItemList = itemList;
    }

    @NonNull
    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        if (viewType == VIEW_TYPE_ITEM) {
            View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_recycler, parent, false);
            return new ItemViewHolder(view);
        } else {
            View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_loading, parent, false);
            return new LoadingViewHolder(view);
        }
    }

    @Override
    public void onBindViewHolder(@NonNull RecyclerView.ViewHolder viewHolder, int position) {

        if (viewHolder instanceof ItemViewHolder) {

            populateItemRows((ItemViewHolder) viewHolder, position);
        } else if (viewHolder instanceof LoadingViewHolder) {
            showLoadingView((LoadingViewHolder) viewHolder, position);
        }

    }

    @Override
    public int getItemCount() {
        return mItemList == null ? 0 : mItemList.size();
    }


    @Override
    public int getItemViewType(int position) {
        return mItemList.get(position) == null ? VIEW_TYPE_LOADING : VIEW_TYPE_ITEM;
    }

    private class ItemViewHolder extends RecyclerView.ViewHolder {

        TextView tvItem;

        public ItemViewHolder(@NonNull View itemView) {
            super(itemView);

            tvItem = itemView.findViewById(R.id.tvItem);
        }
    }


    private class LoadingViewHolder extends RecyclerView.ViewHolder {

        ProgressBar progressBar;

        public LoadingViewHolder(@NonNull View itemView) {
            super(itemView);
            progressBar = itemView.findViewById(R.id.progressBar);
        }
    }

    private void showLoadingView(LoadingViewHolder viewHolder, int position) {
        //
    }

    private void populateItemRows(ItemViewHolder viewHolder, int position) {

        String item = mItemList.get(position);
        viewHolder.tvItem.setText(item);

    }


}

 

 

MainActivity

public class MainActivity extends AppCompatActivity {
    private static final String TAG = "MainActivity";
    RecyclerView recyclerView;
    RecyclerViewAdapter recyclerViewAdapter;

    boolean isLoading = false;

    ArrayList<String> allList = new ArrayList<>();
    ArrayList<String> list = new ArrayList<>();


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        recyclerView = findViewById(R.id.recyclerview);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        firstData();
        initAdapter();
        initScrollListener();
    }



    private void firstData() {
        Log.d(TAG, "firstData:");
        // 총 아이템이 50개라 가정
        for (int a=0; a<50; a++) {
            allList.add("Item " + a);
        }

        // 총 아이템에서 10개를 받아옴
        for (int i=0; i<10; i++) {
            list.add(allList.get(i));
        }
    }

    private void dataMore() {
        Log.d(TAG, "dataMore: ");
        list.add(null);
        recyclerViewAdapter.notifyItemInserted(list.size() -1 );

        Handler handler = new Handler();
        handler.postDelayed(new Runnable() {
            @Override
            public void run() {
                list.remove(list.size() -1 );
                int scrollPosition = list.size();
                recyclerViewAdapter.notifyItemRemoved(scrollPosition);
                int currentSize = scrollPosition;
                int nextLimit = currentSize + 10;

                for (int i=currentSize; i<nextLimit; i++) {
                    if (i == allList.size()) {
                        return;
                    }
                    list.add(allList.get(i));
                }

                recyclerViewAdapter.notifyDataSetChanged();
                isLoading = false;
            }
        }, 2000);

    }


    private void initAdapter() {
        recyclerViewAdapter = new RecyclerViewAdapter(list);
        recyclerView.setAdapter(recyclerViewAdapter);
    }

    // 리싸이클러뷰 이벤트시
    private void initScrollListener() {
        recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrollStateChanged(@NonNull RecyclerView recyclerView, int newState) {
                super.onScrollStateChanged(recyclerView, newState);
                Log.d(TAG, "onScrollStateChanged: ");
            }

            @Override
            public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy) {
                super.onScrolled(recyclerView, dx, dy);
                Log.d(TAG, "onScrolled: ");

                LinearLayoutManager linearLayoutManager = (LinearLayoutManager) recyclerView.getLayoutManager();

                if (!isLoading) {
                    if (linearLayoutManager != null && linearLayoutManager.findLastCompletelyVisibleItemPosition() == list.size() -1 ) {
                        dataMore();
                        isLoading = true;
                        Toast.makeText(MainActivity.this, "스크롤감지", Toast.LENGTH_SHORT).show();
                    }
                }
            }
        });


    }
    
    }

 

참:https://www.journaldev.com/24041/android-recyclerview-load-more-endless-scrolling

 

코틀린 버전 페이징 : class-programming.tistory.com/manage/statistics/entry/108

 

 

 

안드로이드 스터디 모집

www.notion.so/fundevjay/Android-ddf96b24265e414fb2d9e8fc5d388b80