Question

我正在尝试将我的Android Studio项目上的ListView更改为RecycleView，因为我从包含大量字符串的数据库导入数据。我有一个适用于我的ListView的适配器，但我从不使用RecycleView，所以我不知道如何使用它。我搜索了很多主题，但我真的无法理解如何使用它。我希望有人可以帮助我; 这是我的代码：

fragment_one.xml （我的主要是，我已经添加了RecycleView而不是ListView，同样是@id）

<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >

<LinearLayout
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:weightSum="4">
    <Button
        android:id="@+id/frammentoUno"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Gestione Generale"
        android:onClick="FragmentOneClick"
        android:layout_weight="1"/>

    <Button
        android:id="@+id/frammentoDue"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Ultimi Allarmi"
        android:onClick="FragmentTwoClick"
        android:layout_weight="3"/>
</LinearLayout>


<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceMedium"
    android:text="Gestione Generale"
    android:id="@+id/textView3"
    android:layout_gravity="center_horizontal" />

 <!-- A RecyclerView with some commonly used attributes -->
<android.support.v7.widget.RecyclerView
    android:id="@+id/GetAllAllarmiListView"
    android:scrollbars="vertical"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:dividerHeight="1dp"/>

FrammentoUno.java

public class FrammentoUno extends AppCompatActivity {

private ListView GetAllAllarmiListView;
/**
 * ATTENTION: This was auto-generated to implement the App Indexing API.
 * See https://g.co/AppIndexing/AndroidStudio for more information.
 */
private GoogleApiClient mClient;
private Uri mUrl;
private String mTitle;
private String mDescription;

private Button frammentoUno, frammentoDue;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.fragment_one);

    addListenerOnButton();

    this.GetAllAllarmiListView = (ListView) this.findViewById(R.id.GetAllAllarmiListView);

    new GetAllAllarmiTask().execute(new ApiConnector());

    mClient = new GoogleApiClient.Builder(this).addApi(AppIndex.API).build();
    mUrl = Uri.parse("android-app://com.example.andrea/http/host_path");
    mTitle = "Standard Poodle";
    mDescription = "The Standard Poodle stands at least 18 inches at the withers";

    LayoutInflater factory = LayoutInflater.from(this);
    final View textEntryView = factory.inflate(R.layout.get_all_allarmi_list_view_cell, null);

    final CheckBox visto = (CheckBox) textEntryView.findViewById(R.id.visto);
    visto.setOnClickListener(btnListener);
}
  private View.OnClickListener btnListener = new View.OnClickListener() {
    @Override
    public void onClick(View visto) {
        if (visto.isClickable()) {
            startActivity(new Intent(FrammentoUno.this, SQL_visto.class));
            Toast.makeText(FrammentoUno.this,
                    "Visto", Toast.LENGTH_LONG).show();
        } else {
            Toast.makeText(FrammentoUno.this,
                    "Non Visto", Toast.LENGTH_LONG).show();
        }
    }
};

public void addListenerOnButton() {

    frammentoUno = (Button) findViewById(R.id.frammentoUno);
    frammentoDue = (Button) findViewById(R.id.frammentoDue);

    frammentoUno.setOnClickListener(new View.OnClickListener() {

        //Run when button is clicked
        @Override
        public void onClick(View v) {
            Intent i = new Intent(FrammentoUno.this, FrammentoUno.class);

            startActivity(i);
            Toast.makeText(FrammentoUno.this, "Allarmi Generali",
                    Toast.LENGTH_LONG).show();
        }
    });
    frammentoDue.setOnClickListener(new View.OnClickListener() {
        //Run when button is clicked
        @Override
        public void onClick(View v) {
            Intent i = new Intent(FrammentoUno.this, FrammentoDue.class);

            startActivity(i);
            Toast.makeText(FrammentoUno.this, "Controllo Ultimi Allarmi",
                    Toast.LENGTH_LONG).show();
        }
    });
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    int id = item.getItemId();

    switch (id) {
        case R.id.MENU_1:
        /*
            Codice di gestione della voce MENU_1
         */
            startActivity(new Intent(this, ControlloSbarre.class));
            return true;

        case R.id.MENU_2:
             /*
            Codice di gestione della voce MENU_2
         */
            startActivity(new Intent(this, LoginActivity.class));
            return true;
    }
    return false;
}


public void setListAdapter(JSONArray jsonArray) {
    this.GetAllAllarmiListView.setAdapter(new GetAllAllarmiListViewAdapter(jsonArray, this));
}

private class GetAllAllarmiTask extends AsyncTask<ApiConnector, Long, JSONArray> {
    @Override
    protected JSONArray doInBackground(ApiConnector... params) {
        return params[0].GetAllAllarmi();
    }

    @Override
    protected void onPostExecute(JSONArray jsonArray) {
        setListAdapter(jsonArray);
    }
}}

GetAllAllarmiListViewAdapter.java

public class GetAllAllarmiListViewAdapter extends BaseAdapter {

private JSONArray dataArray;
private Activity activity;

private static LayoutInflater inflater = null;

public GetAllAllarmiListViewAdapter(JSONArray jsonArray, Activity a)
{
    this.dataArray = jsonArray;
    this.activity = a;

    inflater = (LayoutInflater) this.activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

}

@Override
public int getCount() {
    return this.dataArray.length();
}

@Override
public Object getItem(int position) {
    return position;
}

@Override
public long getItemId(int position) {
    return position;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {

    // set up convert view if it is null
    ListCell cell;
    if (convertView == null)
    {
        convertView = inflater.inflate(R.layout.get_all_allarmi_list_view_cell, null);
        cell = new ListCell();

        cell.nomeParcheggio = (TextView) convertView.findViewById(R.id.id_park);
        cell.data = (TextView) convertView.findViewById((R.id.data));
        cell.stato = (TextView) convertView.findViewById((R.id.stato));
        cell.descrizione = (TextView) convertView.findViewById((R.id.id_descrizione));
        cell.targa = (TextView) convertView.findViewById((R.id.targa));
        cell.azione = (TextView) convertView.findViewById((R.id.azione));
        cell.dispositivo = (TextView) convertView.findViewById((R.id.dispositivo));

        convertView.setTag(cell);
    }
    else
    {
        cell = (ListCell) convertView.getTag();
    }

    //change the data of cell
    try {

        JSONObject jsonObject = this.dataArray.getJSONObject(position);
        cell.nomeParcheggio.setText(jsonObject.getString("nome"));
        cell.data.setText (jsonObject.getString("data_al"));
        cell.stato.setText(jsonObject.getString("stato"));
        cell.descrizione.setText(jsonObject.getString("descrizione"));
        cell.targa.setText(jsonObject.getString("targa"));
        cell.azione.setText(jsonObject.getString("azione"));

        if (jsonObject.getString("azione")=="1")
        {
            cell.dispositivo.setText(jsonObject.getString("varco"));
        }
        else if (jsonObject.getString("azione")== "2"){
            cell.dispositivo.setText(jsonObject.getString("cassa"));
        }

    }
    catch (JSONException e)
    {
        e.printStackTrace();
    }

    return convertView;
}

private class ListCell
{
    private TextView nomeParcheggio;
    private TextView data;
    private TextView stato;
    private TextView descrizione;
    private TextView targa;
    private TextView azione;
    private TextView dispositivo;
}}

get_all_allarmi_list_view_cell.xml

<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="fill_parent"
android:layout_height="match_parent"
    android:layout_weight="3">

<TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Nome Park"
        android:id="@+id/id_park"
    android:layout_gravity="center_horizontal"
    android:padding="5dp"
    />
<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Data"
    android:id="@+id/data"
    android:layout_gravity="center_horizontal"
    android:padding="5dp"/>
<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Stato"
    android:id="@+id/stato"
    android:layout_gravity="center_horizontal"
    android:padding="5dp"/>

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Descrizione"
    android:id="@+id/id_descrizione"
    android:layout_gravity="center_horizontal"
    android:padding="5dp"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Targa"
android:id="@+id/targa"
    android:layout_gravity="center_horizontal"
    android:padding="5dp"/>

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Azione"
android:id="@+id/azione"
android:layout_gravity="center_horizontal"
android:padding="5dp"/>

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Dispositivo"
    android:id="@+id/dispositivo"
    android:layout_gravity="center_horizontal"
    android:padding="5dp"/>

<CheckBox
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center_horizontal"
    android:id="@+id/visto"
    android:onClick="clickHandler"/>

的AndroidManifest.xml

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.andrea.gestionesbarre">

<uses-permission android:name="android.permission.INTERNET" />

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_citiware"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">

    <activity android:name=".Frammenti_LogIn_Menu.LoginActivity">
    <intent-filter>
    <action android:name="android.intent.action.MAIN" />

    <category android:name="android.intent.category.LAUNCHER" />
   </intent-filter>
    </activity>

    <activity android:name="com.example.andrea.FrammentoUno">
    </activity>

    <activity android:name="com.example.andrea.FrammentoDue"></activity>
    <!--
     ATTENTION: This was auto-generated to add Google Play services to your project for
     App Indexing.  See https://g.co/AppIndexing/AndroidStudio for more information.
    -->
    <activity android:name=".Frammenti_LogIn_Menu.ControlloSbarre">
        <meta-data
            android:name="android.support.PARENT_ACTIVITY"
            android:value="com.example.andrea.FrammentoUno" />
    </activity>
</application>

我已经在我的gradle中添加了依赖项。

感谢您的帮助

Answer 1

您必须在适配器类中进行更改。这是我的示例类，它是适用于回收站视图的适配器。

 public class NavigationDrawerAdapter extends RecyclerView.Adapter<NavigationDrawerAdapter.MyViewHolder> {

    List<NavDrawerItem> data = Collections.emptyList();
    private LayoutInflater inflater;
    private Context context;

    public NavigationDrawerAdapter(Context context, List<NavDrawerItem> data) {
        this.context = context;
        inflater = LayoutInflater.from(context);
        this.data = data;
    }



    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = inflater.inflate(R.layout.nav_drawer_row, parent, false);
        MyViewHolder holder = new MyViewHolder(view);
        return holder;
    }

    @Override
    public void onBindViewHolder(MyViewHolder holder, int position) {
        NavDrawerItem current = data.get(position);
        holder.title.setText(current.getTitle());
        holder.iv.setImageResource(current.getIcon().getResourceId(position,1));

    }

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

    class MyViewHolder extends RecyclerView.ViewHolder {
        TextView title;
        ImageView iv;

        public MyViewHolder(View itemView) {
            super(itemView);
            title = (TextView) itemView.findViewById(R.id.title);
            iv = (ImageView) itemView.findViewById(R.id.nav_drawer_row_icon);
         }
    }
}

将此行放在您的java代码中

 recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));

Answer 2

我修改了你的完整适配器类，如下所示：

def decorator(func):
    def wrapped(a, b, c):
        return c + func(a, b)
    return wrapped

@decorator
def add(a, b):
    return (a+b)

现在修改活动中的setListAdapter（）方法，如下所示：

public class GetAllAllarmiListViewAdapter extends RecyclerView.Adapter<GetAllAllarmiListViewAdapter.MyViewHolder>{

private JSONArray dataArray;
private Activity activity;

private static LayoutInflater inflater = null;

// Provide a suitable constructor (depends on the kind of dataset)
public GetAllAllarmiListViewAdapter(JSONArray jsonArray, Activity a) {
    this.dataArray = jsonArray;
    this.activity = a;

    inflater = (LayoutInflater) this.activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}

@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    // create a new view
    View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.get_all_allarmi_list_view_cell, parent, false);
    // set the view's size, margins, paddings and layout parameters
    MyViewHolder vh = new MyViewHolder(v);
    return vh;
}

@Override
public void onBindViewHolder(MyViewHolder holder, int position) {
    try {

        JSONObject jsonObject = this.dataArray.getJSONObject(position);
        holder.nomeParcheggio.setText(jsonObject.getString("nome"));
        holder.data.setText (jsonObject.getString("data_al"));
        holder.stato.setText(jsonObject.getString("stato"));
        holder.descrizione.setText(jsonObject.getString("descrizione"));
        holder.targa.setText(jsonObject.getString("targa"));
        holder.azione.setText(jsonObject.getString("azione"));

        if (jsonObject.getString("azione")=="1")
        {
            holder.dispositivo.setText(jsonObject.getString("varco"));
        }
        else if (jsonObject.getString("azione")== "2"){
            holder.dispositivo.setText(jsonObject.getString("cassa"));
        }

    }
    catch (JSONException e)
    {
        e.printStackTrace();
    }

}

@Override
public int getItemCount() {
    return dataArray.length();
}

public class MyViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener{
    // each data item is just a string in this case
    private TextView nomeParcheggio;
    private TextView data;
    private TextView stato;
    private TextView descrizione;
    private TextView targa;
    private TextView azione;
    private TextView dispositivo;

    public MyViewHolder(View v) {
        super(v);
        nomeParcheggio = (TextView) v.findViewById(R.id.id_park);
        data = (TextView) v.findViewById((R.id.data));
        stato = (TextView) v.findViewById((R.id.stato));
        descrizione = (TextView) v.findViewById((R.id.id_descrizione));
        targa = (TextView) v.findViewById((R.id.targa));
        azione = (TextView) v.findViewById((R.id.azione));
        dispositivo = (TextView) v.findViewById((R.id.dispositivo));
        v.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        int position = getAdapterPosition();
        // It will be called if you click on a list item. variable position contains the position of the item in the adapter. You can do whatever you want with the position..
    }
}

}

在活动中不要忘记用RecyclerView替换listView：

public void setListAdapter(JSONArray jsonArray) {
  RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(this);
  this.GetAllAllarmiListView.setLayoutManager(layoutManager);
  this.GetAllAllarmiListView.setAdapter(new GetAllAllarmiListViewAdapter(jsonArray, this));
}

在onCreate（）方法中初始化recyclerView：

private RecyclerView GetAllAllarmiListView;

Listview to Recycleview

2 个答案: