标签：一行代码 ram ems 基础 需要 raw back size ati
学习自：博客园 CSDN Android 官方文档
Android 呈现数据的方式有很多种，使用自定义控件，使用 ListView，使用Recyclerview.
那么我们今天看一下Android 中 如是使用 Recyclerview。
官方文档所示，我们需要声明以下依赖性：
dependencies {
implementation "androidx.recyclerview:recyclerview:1.1.0"
// For control over item selection of both touch and mouse driven selection
implementation "androidx.recyclerview:recyclerview-selection:1.1.0-beta01"
}<?xml version="1.0" encoding="utf-8"?>
<androidx.drawerlayout.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:card_view="http://schemas.android.com/apk/res-auto"
xmlns:tool="http://schemas.android.com/tools"
android:id="@+id/drawLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:animateLayoutChanges="true"
android:orientation="vertical"
tool:context=".MainPackage.MainActivity">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<androidx.appcompat.widget.Toolbar
android:id="@+id/toolbarLibrary"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#517EB9"
android:fitsSystemWindows="true"
app:layout_scrollFlags="scroll|enterAlways"
app:popupTheme="@style/Theme.AppCompat.Light"
app:titleTextColor="#fff" />
<AutoCompleteTextView
android:id="@+id/auto2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="10dp"
android:layout_marginRight="10dp"
android:text="MultiAutoCompleteTextView" />
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/LibraryListview"
class="androidx.appcompat.app.AlertController$RecycleListView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="center"
android:layout_marginLeft="10dp"
android:layout_marginRight="10dp"
android:overScrollMode="never">
</androidx.recyclerview.widget.RecyclerView>
<MultiAutoCompleteTextView
android:id="@+id/multiAutoCompleteTextView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="MultiAutoCompleteTextView" />
</LinearLayout>
<com.google.android.material.navigation.NavigationView
android:id="@+id/navigationViewLilbary"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="start"
app:menu="@menu/library_items_menu" />
</androidx.drawerlayout.widget.DrawerLayout>这样 我们的布局文件就创建完成了。这边不做过多的解释。
Recyclerview我们已经在布局文件中创建好了我们的Recyclerview。
接着我们看一下如何使用它吧。
public class LibraryMainActivity extends AppCompatActivity {
NavigationView navigationView;
DrawerLayout drawerLayout;
TextView txtEmail;
TextView txtName;
ImageView UserImageView;
List<String> listImage = new ArrayList<>();
Toolbar toolbar;
RecyclerView recyclerView;
LinearLayoutManager linearLayoutManager;
List<String> list = new ArrayList<>();
List<String> SearchNameList = new ArrayList<>();
AutoCompleteTextView SearchAuto;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_library_main);
//region -实例化基础控件等-
drawerLayout = findViewById(R.id.drawLayout);
navigationView = findViewById(R.id.navigationViewLilbary);
txtEmail = findViewById(R.id.txtEmail);
txtName = findViewById(R.id.txtName);
toolbar = findViewById(R.id.toolbarLibrary);
toolbar.setTitle("欢迎使用图书馆");
toolbar.setLogo(R.drawable.ic_action_name);
this.setSupportActionBar(toolbar);
// endregion
//region -基础设置-
toolbar.setOnClickListener(v -> {
drawerLayout.openDrawer(navigationView);
});
GetUserInformation();
//设置 沉浸式体验
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
getWindow().getDecorView().setSystemUiVisibility(
View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN);
}
//endregion
linearLayoutManager = new LinearLayoutManager(this);
recyclerView = findViewById(R.id.LibraryListview);
StaggeredGridLayoutManager layoutManager = new StaggeredGridLayoutManager(2, StaggeredGridLayoutManager.VERTICAL);
recyclerView.setLayoutManager(layoutManager);
recyclerView.setItemAnimator(new DefaultItemAnimator());
int a = 100;
for (int i = 0; i < a; i++) {
list.add("第一行代码 - 郭霖\t(第二版)" + String.valueOf(i));
SearchNameList.add("第一行代码 - 郭霖\t(第二版)" + String.valueOf(i));
}
recyclerView.setAdapter(new RecyclerViewAdapter(LibraryMainActivity.this, list));
SearchAuto = findViewById(R.id.auto2);
SearchAuto.setAdapter(new ArrayAdapter<>(LibraryMainActivity.this, android.R.layout.simple_spinner_dropdown_item, SearchNameList));
}
/**
*@ClassName:LibraryMainActivity - 用于获取 当前登录用户的个人信息，头像等。
*@author:CaoJiaHao
*@Param:
**/
void GetUserInformation() {
new Thread(new Runnable() {
@Override
public void run() {
String ImageString = Global.HttpGet("UserInformations/" + SessionClass.userClass.get(0).getUserId(), null);
listImage = UserImageJSON.modelJson(ImageString);
String imageString = listImage.get(0);
final Bitmap Userbitmap = Global.StringToBitmap(imageString);
runOnUiThread(new Runnable() {
@Override
public void run() {
View viewHearder = navigationView.inflateHeaderView(R.layout.nav_header);
txtName = viewHearder.findViewById(R.id.txtName);
txtEmail = viewHearder.findViewById(R.id.txtEmail);
UserImageView = viewHearder.findViewById(R.id.UserImageView);
txtName.setText("User Name: " + SessionClass.userClass.get(0).getUserName());
txtEmail.setText("Email: " + SessionClass.userClass.get(0).getEmail());
UserImageView.setImageBitmap(Userbitmap);
//处理当前登录这没有头像的情况
if (Userbitmap == null || Userbitmap.isRecycled())
UserImageView.setImageResource(R.drawable.user_image);
}
});
}
}).start();
}
}这样我们在活动中使用使用我们的Recyclerview就完成了。
当时我们可以看到，在程序中我们使用到了适配器。
接下来我们就看一下适配器是如何编写的。
如果之前学过Recyclerview的人可能知道。在Recyclerview中并没有给你封装好的单击事件和长按事件等。那么这就意味着。我们需要自己写。
我们先看一下我们的适配器源码：
public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private Context mContext;
private List<String> mList = new ArrayList<>();
TextView textView;
ImageView booksImage;
public RecyclerViewAdapter(Context mContext, List<String> mList) {
this.mContext = mContext;
this.mList = mList;
}
@NonNull
@Override
public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(mContext).inflate(R.layout.r_view_items, parent, false);
textView = view.findViewById(R.id.text_view);
booksImage = view.findViewById(R.id.booksImageView);
return new ViewHodel(view);
}
@Override
public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {
textView.setText(mList.get(position));
holder.itemView.setOnClickListener(v -> {
Toast.makeText(mContext, "Hello android", Toast.LENGTH_SHORT).show();
});
holder.itemView.setOnLongClickListener(v -> {
View viewInformation = LayoutInflater.from(mContext).inflate(R.layout.book_information, null, false);
ImageView imageView = viewInformation.findViewById(R.id.booksInformationImageView);
TextView txtName = viewInformation.findViewById(R.id.txtBookName);
txtName.setText(textView.getText());
Bitmap bitmap = ((BitmapDrawable) booksImage.getDrawable()).getBitmap();
imageView.setImageBitmap(bitmap);
AlertDialog dialog = new AlertDialog.Builder(mContext).setView(viewInformation).show();
return true;
});
}
@Override
public int getItemCount() {
return mList.size();
}
}
class ViewHodel extends RecyclerView.ViewHolder {
private TextView txtName;
public ViewHodel(@NonNull View itemView) {
super(itemView);
txtName = itemView.findViewById(R.id.text_view);
}
}然后我们根据源码来看一下：
RecyclerviewAdapter并且继承于RecyclerView.Adapter<RecyclerView.ViewHolder>ContextonCreateViewHolder方法。onBindViewHolder方法了。这边我注册了部分的点击事件。getItemCount();的方法了。他的主要用途返回我们的items数量。看一下效果：
这篇可能不太对因为个人工作问题，在开发中不会去使用任何依赖。所以这篇只是拓展视野而已。??
标签：一行代码 ram ems 基础 需要 raw back size ati
原文地址：https://www.cnblogs.com/cao-1/p/12089599.html
