应用程序崩溃并出现“android.app.Application 无法转换为”

Question

我正在发现 ORMlite。所以，我有这个 DAO 工厂类

public class DtoFactory extends Application {

    private SharedPreferences preferences;
    private DatabaseHelper databaseHelper = null;

    private Dao<ReleveEntity, Integer> releveDAO = null;

    @Override
    public void onCreate() {
            super.onCreate();
            preferences = PreferenceManager.getDefaultSharedPreferences(this);
            databaseHelper = new DatabaseHelper(this);
    }

    public SharedPreferences getPreferences() {return preferences;}

    public Dao<ReleveEntity, Integer> getReleveDao() throws SQLException, java.sql.SQLException {
            if (releveDAO == null) {
                releveDAO = databaseHelper.getDao(ReleveEntity.class);
            }
            return releveDAO;
    }

    @Override
    public void onTerminate() {
            super.onTerminate();
            if (databaseHelper != null) {
                    OpenHelperManager.releaseHelper();
                    databaseHelper = null;
            }
    }
} 

在主目录中，我将只显示我遇到问题的这几行：

 @Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    dtoFactory = (DtoFactory) getApplication();

还有 manifest.xml

   <application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name="com.exercice.ftouzi.ReleveActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

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

消息错误是：

 E/AndroidRuntime(19672): FATAL EXCEPTION: main
 E/AndroidRuntime(19672): java.lang.RuntimeException: Unable to start activity
      ComponentInfo{com.formation.adapter/com.exercice.ftouzi.ReleveActivity}: 
      java.lang.ClassCastException: android.app.Application cannot be cast to
      com.exercice.ormdatabase.DtoFactory

你能帮我解决这个问题吗？

Answer 1

您需要在 AndroidManifest.xml 中指定您的自定义Application（即DtoFactory）

   <application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" 
    android:name="com.exercice.ormdatabase.DtoFactory">
    <activity
        android:name="com.exercice.ftouzi.ReleveActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>