如何在 Android Studio 中将 ListView 更改为 RecyclerView？

Posted 2023-05-07

【中文标题】如何在 Android Studio 中将 ListView 更改为 RecyclerView？

【英文标题】：How to change ListView to RecyclerView in Android Studio?

【发布时间】：2020-08-11 23:44:03

【问题描述】：

不知道怎么用RecyclerView来代替ListView。任何人都可以帮助我吗？谢谢你。我在不同的在线平台上找到了很多资源，但我不知道如何更改我的代码。当我尝试更改我的代码时，它不起作用。

代码如下：

MainActivity.java

public class MainActivity extends AppCompatActivity 

    private String TAG = MainActivity.class.getSimpleName();

    private ProgressDialog pDialog;
    private ListView lv;

    // URL to get contacts JSON
    private static String url = "https://api.androidhive.info/contacts/";

    ArrayList<HashMap<String, String>> contactList;

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

        contactList = new ArrayList<>();

        lv = (ListView) findViewById(R.id.list);

        new GetContacts().execute();
    

    /**
     * Async task class to get json by making HTTP call
     */
    private class GetContacts extends AsyncTask<Void, Void, Void> 

        @Override
        protected void onPreExecute() 
            super.onPreExecute();
            // Showing progress dialog
            pDialog = new ProgressDialog(MainActivity.this);
            pDialog.setMessage("Please wait...");
            pDialog.setCancelable(false);
            pDialog.show();

        

        @Override
        protected Void doInBackground(Void... arg0) 
            HttpHandler sh = new HttpHandler();

            // Making a request to url and getting response
            String jsonStr = sh.makeServiceCall(url);

            Log.e(TAG, "Response from url: " + jsonStr);

            if (jsonStr != null) 
                try 
                    JSONObject jsonObj = new JSONObject(jsonStr);

                    // Getting JSON Array node
                    JSONArray contacts = jsonObj.getJSONArray("contacts");

                    // looping through All Contacts
                    for (int i = 0; i < contacts.length(); i++) 
                        JSONObject c = contacts.getJSONObject(i);

                        String id = c.getString("id");
                        String name = c.getString("name");
                        String email = c.getString("email");
                        String address = c.getString("address");
                        String gender = c.getString("gender");

                        // Phone node is JSON Object
                        JSONObject phone = c.getJSONObject("phone");
                        String mobile = phone.getString("mobile");
                        String home = phone.getString("home");
                        String office = phone.getString("office");

                        // tmp hash map for single contact
                        HashMap<String, String> contact = new HashMap<>();

                        // adding each child node to HashMap key => value
                        contact.put("id", id);
                        contact.put("name", name);
                        contact.put("email", email);
                        contact.put("mobile", mobile);

                        // adding contact to contact list
                        contactList.add(contact);
                    
                 catch (final JSONException e) 
                    Log.e(TAG, "Json parsing error: " + e.getMessage());
                    runOnUiThread(new Runnable() 
                        @Override
                        public void run() 
                            Toast.makeText(getApplicationContext(),
                                    "Json parsing error: " + e.getMessage(),
                                    Toast.LENGTH_LONG)
                                    .show();
                        
                    );

                
             else 
                Log.e(TAG, "Couldn't get json from server.");
                runOnUiThread(new Runnable() 
                    @Override
                    public void run() 
                        Toast.makeText(getApplicationContext(),
                                "Couldn't get json from server. Check LogCat for possible errors!",
                                Toast.LENGTH_LONG)
                                .show();
                    
                );

            

            return null;
        

        @Override
        protected void onPostExecute(Void result) 
            super.onPostExecute(result);
            // Dismiss the progress dialog
            if (pDialog.isShowing())
                pDialog.dismiss();

            ListAdapter adapter = new SimpleAdapter(
                    MainActivity.this, contactList,
                    R.layout.list_item, new String[]"name", "email",
                    "mobile", new int[]R.id.name,
                    R.id.email, R.id.mobile);

            lv.setAdapter(adapter);
        

    

HttpHandler.java

public class HttpHandler 

    private static final String TAG = HttpHandler.class.getSimpleName();

    public HttpHandler() 
    

    public String makeServiceCall(String reqUrl) 
        String response = null;
        try 
            URL url = new URL(reqUrl);
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setRequestMethod("GET");
            // read the response
            InputStream in = new BufferedInputStream(conn.getInputStream());
            response = convertStreamToString(in);
         catch (MalformedURLException e) 
            Log.e(TAG, "MalformedURLException: " + e.getMessage());
         catch (ProtocolException e) 
            Log.e(TAG, "ProtocolException: " + e.getMessage());
         catch (IOException e) 
            Log.e(TAG, "IOException: " + e.getMessage());
         catch (Exception e) 
            Log.e(TAG, "Exception: " + e.getMessage());
        
        return response;
    

    private String convertStreamToString(InputStream is) 
        BufferedReader reader = new BufferedReader(new InputStreamReader(is));
        StringBuilder sb = new StringBuilder();

        String line;
        try 
            while ((line = reader.readLine()) != null) 
                sb.append(line).append('\n');
            
         catch (IOException e) 
            e.printStackTrace();
         finally 
            try 
                is.close();
             catch (IOException e) 
                e.printStackTrace();
            
        
        return sb.toString();
    

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_
    android:layout_
    tools:context="hk.edu.ouhk.android.jsonparsing.MainActivity">

    <ListView
        android:id="@+id/list"
        android:layout_
        android:layout_
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

list_item.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_
    android:layout_
    android:orientation="vertical"
    android:padding="16dip">

    <TextView
        android:id="@+id/name"
        android:layout_
        android:layout_
        android:paddingBottom="2dip"
        android:paddingTop="6dip"
        android:textColor="@color/colorPrimaryDark"
        android:textSize="16sp"
        android:textStyle="bold" />

    <TextView
        android:id="@+id/email"
        android:layout_
        android:layout_
        android:paddingBottom="2dip"
        android:textColor="#5d5d5d" />

    <TextView
        android:id="@+id/mobile"
        android:layout_
        android:layout_
        android:textColor="#686868"
        android:textStyle="bold" />

</LinearLayout>

【问题讨论】：

你说的不起作用是什么意思？你遇到了什么错误？

【参考方案1】：

因为您从 url 获取数据似乎没有问题，并且您已经成功地从数据中创建了一个 Arraylist

现在要遵循的步骤 1.将recyclerview添加到活动的xml中 2. 做一个布局，你想如何在 recyclerview 项目中显示数据 3. 然后你需要制作一个适配器来接收你提供的数据并将其绑定到 回收站视图 4. 然后将适配器添加到您的回收站视图中

我附上了我不久前为我制作的简单回收站视图。它很简单且不言自明。否则你可以评论我会解释更多

Main Activity
public class MainActivity extends AppCompatActivity 
ArrayList<String> moviesList;
RecyclerView recyclerView;
RecyclerAdapter recyclerAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) 
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    moviesList=new ArrayList<>();
    recyclerView=findViewById(R.id.recyclerView);
    recyclerAdapter=new RecyclerAdapter(moviesList);
    recyclerView.setLayoutManager(new LinearLayoutManager(this));
    recyclerView.setAdapter(recyclerAdapter);
    moviesList.add("Kapil");
    moviesList.add("Kapil");
    moviesList.add("Kapil");
    moviesList.add("Kapil");
    moviesList.add("Kapil");
    moviesList.add("Kapil");
    moviesList.add("Kapil"); 
 



RecyclerAdapter in this we are creating custom viewholder for us
public class RecyclerAdapter extends RecyclerView.Adapter<RecyclerAdapter.ViewHolder> 
  
public RecyclerAdapter(ArrayList<String> moviesList) 
    this.moviesList = moviesList;


ArrayList<String> moviesList;
@NonNull
@Override
public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) 
    LayoutInflater layoutInflater=LayoutInflater.from(parent.getContext());
    View view=layoutInflater.inflate(R.layout.row_layout,parent,false);
    ViewHolder viewHolder= new ViewHolder(view);
    return viewHolder;


@Override
public void onBindViewHolder(@NonNull ViewHolder holder, int position) 
holder.rowTextView.setText(String.valueOf(position));
holder.textView.setText(moviesList.get(position));


@Override
public int getItemCount() 
    return moviesList.size();


class ViewHolder extends RecyclerView.ViewHolder 
    ImageView imageView;
    TextView textView,rowTextView;
    public ViewHolder(@NonNull View itemView) 
        super(itemView);
        imageView=itemView.findViewById(R.id.imageView);
        textView=itemView.findViewById(R.id.textView);
        rowTextView=itemView.findViewById(R.id.rowTextView);
    
  
 

 This is layout for the item which I want to show in recycler view
  <?xml version="1.0" encoding="utf-8"?>
 <androidx.constraintlayout.widget.ConstraintLayout 
 xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_
android:layout_>

<ImageView
    android:id="@+id/imageView"
    android:layout_
    android:layout_
    android:layout_marginStart="22dp"
    android:layout_marginTop="16dp"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    app:srcCompat="@drawable/ic_launcher_background" />

<TextView
    android:id="@+id/textView"
    android:layout_
    android:layout_
    android:layout_marginStart="32dp"
    android:layout_marginTop="22dp"
    android:text="TextView"
    android:textAppearance="@style/TextAppearance.AppCompat.Large"
    app:layout_constraintStart_toEndOf="@+id/imageView"
    app:layout_constraintTop_toTopOf="parent" />

<TextView
    android:id="@+id/rowTextView"
    android:layout_
    android:layout_
    android:layout_marginStart="33dp"
    android:layout_marginTop="16dp"
    android:text="TextView"
    app:layout_constraintStart_toEndOf="@+id/imageView"
    app:layout_constraintTop_toBottomOf="@+id/textView" />
   </androidx.constraintlayout.widget.ConstraintLayout>

只需将您的数组列表传递给它。和我一样

【参考方案2】：

基本上你需要用 ViewHolder 模式创建 RecyclerViewAdapter，只需简单地将 ListView 替换为 RecyclerView

【讨论】：

但是不知道ViewHolder怎么写。你能给我一些提示吗？谢谢。

这很简单，只需阅读几篇像这样的初学者帖子grokkingandroid.com/first-glance-androids-recyclerview