이 예는 Android에서 RecyclerView를 사용하여 무한 목록을 구현하는 방법을 보여줍니다.
1단계 − Android Studio에서 새 프로젝트를 생성하고 파일 ⇒ 새 프로젝트로 이동하여 필요한 모든 세부 정보를 입력하여 새 프로젝트를 생성합니다.
빌드 gradle(모듈 앱)에 다음 종속성을 추가합니다. −
implementation 'com.android.support:cardview-v7:28.0.0' implementation 'com.android.support:recyclerview-v7:28.0.0'
2단계 − res/layout/activity_main.xml에 다음 코드를 추가합니다.
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="https://schemas.android.com/apk/res/android" xmlns:tools="https://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" tools:context=".MainActivity"> <androidx.recyclerview.widget.RecyclerView android:id="@+id/recyclerView" android:layout_width="match_parent" android:layout_height="wrap_content" /> </LinearLayout>
3단계 − src/MainActivity.java
에 다음 코드 추가import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import android.os.Bundle;
import android.os.Handler;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity {
RecyclerView recyclerView;
RecyclerViewAdapter recyclerViewAdapter;
ArrayList<String>rowsArrayList = new ArrayList<>();
boolean isLoading = false;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
recyclerView = findViewById(R.id.recyclerView);
populateData();
initAdapter();
initScrollListener();
}
private void populateData() {
for (int i = 0; i < 10; i++) {
rowsArrayList.add("Number " + i);
}
}
private void initAdapter() {
recyclerViewAdapter = new RecyclerViewAdapter(rowsArrayList);
recyclerView.setLayoutManager(new LinearLayoutManager(getApplicationContext()));
recyclerView.setAdapter(recyclerViewAdapter);
}
private void initScrollListener() {
recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrollStateChanged(@NonNull RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
}
@Override
public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
LinearLayoutManager linearLayoutManager = (LinearLayoutManager) recyclerView.getLayoutManager();
if (!isLoading) {
if (linearLayoutManager != null && linearLayoutManager.findLastCompletelyVisibleItemPosition() == rowsArrayList.size() - 1) {
//bottom of list!
loadMore();
isLoading = true;
}
}
}
});
}
private void loadMore() {
rowsArrayList.add(null);
recyclerViewAdapter.notifyItemInserted(rowsArrayList.size() - 1);
Handler handler = new Handler();
handler.postDelayed(new Runnable() {
@Override
public void run() {
rowsArrayList.remove(rowsArrayList.size() - 1);
int scrollPosition = rowsArrayList.size();
recyclerViewAdapter.notifyItemRemoved(scrollPosition);
int currentSize = scrollPosition;
int nextLimit = currentSize + 10;
while (currentSize - 1 < nextLimit) {
rowsArrayList.add("Number " + currentSize);
currentSize++;
}
recyclerViewAdapter.notifyDataSetChanged();
isLoading = false;
}
}, 2000);
}
} 4단계 − 새 Java 클래스(RecyclerViewAdapter.java)를 만들고 다음 코드를 추가합니다. −
package app.com.sample;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ProgressBar;
import android.widget.TextView;
import java.util.List;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
public class RecyclerViewAdapter extends
RecyclerView.Adapter<RecyclerView.ViewHolder> {
private final int VIEW_TYPE_ITEM = 0;
private List<String> mItemList;
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_row, 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) {
int VIEW_TYPE_LOADING = 1;
return mItemList.get(position) == null ? VIEW_TYPE_LOADING :
VIEW_TYPE_ITEM;
}
private class ItemViewHolder extends RecyclerView.ViewHolder {
TextView tvItem;
ItemViewHolder(@NonNull View itemView) {
super(itemView);
tvItem = itemView.findViewById(R.id.textViewItem);
}
}
private class LoadingViewHolder extends RecyclerView.ViewHolder {
ProgressBar progressBar;
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);
}
} 5단계 − 새로운 Layout 리소스 파일(item_row.xml)을 생성하고 다음 코드를 추가합니다. −
<?xml version="1.0" encoding="utf-8"?> <androidx.cardview.widget.CardView xmlns:android="https://schemas.android.com/apk/res/android" xmlns:app="https://schemas.android.com/apk/res-auto" android:layout_width="match_parent" android:layout_height="wrap_content" app:cardElevation="2dp" app:cardUseCompatPadding="true"> <TextView android:id="@+id/textViewItem" android:layout_width="match_parent" android:layout_height="wrap_content" android:padding="16dp" /> </androidx.cardview.widget.CardView>
6단계 − 새로운 Layout 리소스 파일(item_loading.xml)을 생성하고 다음 코드를 추가합니다. −
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="https://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" 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>
7단계 − androidManifest.xml에 다음 코드 추가
<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="https://schemas.android.com/apk/res/android" package="app.com.sample"> <application android:allowBackup="true" android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:roundIcon="@mipmap/ic_launcher_round" android:supportsRtl="true" android:theme="@style/AppTheme"> <activity android:name=".MainActivity"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> </manifest>
응용 프로그램을 실행해 보겠습니다. 실제 Android 모바일 장치를 컴퓨터에 연결했다고 가정합니다. Android 스튜디오에서 앱을 실행하려면 프로젝트의 활동 파일 중 하나를 열고 도구 모음에서 실행 아이콘을 클릭합니다. 모바일 장치를 옵션으로 선택한 다음 기본 화면을 표시할 모바일 장치를 확인하십시오 -
