Question

我的计划是计算一些食物的卡路里。这是CS课程的一种做法。我是Android操作系统的初学者，我不知道为什么我的接收过程无法完成或显示在Activity上。

我只是在这里写相关的代码片段。我在sqlite数据库上有一些项目，我可以使用Log.d方法在数据库上检查我的项目，它们没问题。

App1的：

清单：

<receiver android:name="ItemBroadcastReceiver"
            android:exported="true">
    <intent-filter>
        <action android:name="com.example.furkan.datagenerator" />

    </intent-filter>
</receiver>

Received.class

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.received);

    ItemBroadcastReceiver br = new ItemBroadcastReceiver();
    Cursor cursor = (Cursor) br.receivedItem;
    ReceivedItemsAdapter adapter = new ReceivedItemsAdapter(this, cursor);
    ListView listView = getListView();
    listView.setAdapter(adapter);
}

适配器：

public class ReceivedItemsAdapter extends CursorAdapter {
public ReceivedItemsAdapter(Context context, Cursor c) {
    super(context, c);
}

@Override
public View newView(Context context, Cursor cursor, ViewGroup parent) {
    LayoutInflater inflater = LayoutInflater.from(parent.getContext());
    View retView = inflater.inflate(R.layout.received, parent, false);

    return retView;
}

@Override
public void bindView(View view, Context context, Cursor cursor) {
    //ImageView icon = (ImageView) view.findViewById(R.id.icon);
    TextView name = (TextView) view.findViewById(R.id.name);
    TextView cal = (TextView) view.findViewById(R.id.amountCal);
    TextView unit = (TextView) view.findViewById(R.id.unit);
    unit.setText(" cal");
    name.setText(cursor.getString(cursor.getColumnIndex(cursor.getColumnName(1))));
    cal.setText(cursor.getString(cursor.getColumnIndex(cursor.getColumnName(2))));

}}

广播接收器：

public class ItemBroadcastReceiver extends BroadcastReceiver {
Item receivedItem;
@Override
public void onReceive(Context context, Intent intent) {
    Bundle bundle = intent.getExtras();

    receivedItem = new Item(bundle.getString("name"),
                                Integer.parseInt(bundle.getString("calories")),
                                bundle.getString("category"),
                                null);
}}

App2的：

MainActivity：

public class MainActivity extends AppCompatActivity {
final int DELAY = 60000;
ReceivedItem item;
@Override
protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    ReceivedItemsDatabaseHelper dbHelper = new        ReceivedItemsDatabaseHelper(this);


    item = new ReceivedItem(dbHelper.fetchReceivedItem().getString(
            dbHelper.fetchReceivedItem().getColumnIndex(
                    dbHelper.fetchReceivedItem().getColumnName(1))),
            Integer.parseInt(dbHelper.fetchReceivedItem().getString(
                    dbHelper.fetchReceivedItem().getColumnIndex(
                            dbHelper.fetchReceivedItem().getColumnName(2)))),
            dbHelper.fetchReceivedItem().getString(
                    dbHelper.fetchReceivedItem().getColumnIndex(
                            dbHelper.fetchReceivedItem().getColumnName(3))), null);

    Thread thread = new Thread() {
        public void run() {
            synchronized (this) {
                try {
                    Log.d("Response ", item.getName()+", "+item.getCategory()+", "+item.getCalories());
                    Intent intent = new Intent();
                    intent.setAction("com.example.furkan.datagenerator");
                    intent.putExtra("name", item.getName());
                    intent.putExtra("calories", item.getCalories());
                    intent.putExtra("category", item.getCategory());
                    sendBroadcast(intent);
                    sleep(DELAY);
                } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }

            }
        }
    };
    thread.start();
}}

清单：

<?xml version="1.0" encoding="utf-8"?>

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity
        android:name=".MainActivity"
        android:label="@string/app_name"
        android:theme="@style/AppTheme.NoActionBar">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

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

Answer 1

IntentFilter filter = new IntentFilter();
filter.addAction("com.example.furkan.datagenerator");

ItemBroadcastReceiver br = new ItemBroadcastReceiver();
registerReceiver(br, filter);

Answer 2

您应该再次阅读BroadcastReceivers。

ItemBroadcastReceiver br = new ItemBroadcastReceiver();
Cursor cursor = (Cursor) br.receivedItem;
ReceivedItemsAdapter adapter = new ReceivedItemsAdapter(this, cursor);
ListView listView = getListView();
listView.setAdapter(adapter);

这将创建接收器的新实例，并将receivedItem分配给cursor。但receivedItem为null，因为您从未为广播注册br，所以永远不会null。我也不确定，如果Item可以投放到Cursor。

考虑到您在此处发布的代码以及您使用的标题，使用BroadcastReceiver可能根本不是一个好主意。您应该尝试通过意图将数据传递到Received或直接从持久存储加载数据。

最后你的thread没有任何意义。

广播不接收两个自定义应用程序之间

2 个答案: