我試圖將一個上下文轉換爲一個Activity。我需要這樣做來調用其中一個活動的方法。爲了獲得我需要的上下文，我使用了getApplicationContext（）。我現在正在開發的應用程序使用Sugar ORM作爲數據庫框架。這是我得到的代碼和例外。Sugar ORM：嘗試從getApplicationContext（）轉換上下文時出現類轉換異常

ContentResolver.requestSync(((MainActivity) getApplicationContext()).getAccount(), AccountHelper.AUTHORITY, settingsBundle); 

java.lang.ClassCastException: com.orm.SugarApp cannot be cast to id.ac.ui.presentronik.activity.MainActivity 
     at id.ac.ui.presentronik.activity.SessionActivity.onOptionsItemSelected(SessionActivity.java:173) 
     at android.app.Activity.onMenuItemSelected(Activity.java:2885) 
     at android.support.v4.app.FragmentActivity.onMenuItemSelected(FragmentActivity.java:350) 
     at android.support.v7.app.ActionBarActivity.onMenuItemSelected(ActionBarActivity.java:155) 
     at android.support.v7.app.ActionBarActivityDelegate$1.onMenuItemSelected(ActionBarActivityDelegate.java:74) 
     at android.support.v7.widget.WindowCallbackWrapper.onMenuItemSelected(WindowCallbackWrapper.java:44) 
     at android.support.v7.internal.app.ToolbarActionBar$2.onMenuItemClick(ToolbarActionBar.java:77) 
     at android.support.v7.widget.Toolbar$1.onMenuItemClick(Toolbar.java:163) 
     at android.support.v7.widget.ActionMenuView$MenuBuilderCallback.onMenuItemSelected(ActionMenuView.java:738) 
     at android.support.v7.internal.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:802) 
     at android.support.v7.internal.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:153) 
     at android.support.v7.internal.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:949) 
     at android.support.v7.internal.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:939) 
     at android.support.v7.widget.ActionMenuView.invokeItem(ActionMenuView.java:596) 
     at android.support.v7.internal.view.menu.ActionMenuItemView.onClick(ActionMenuItemView.java:145) 
     at android.view.View.performClick(View.java:4856) 
     at android.view.View$PerformClick.run(View.java:19956) 
     at android.os.Handler.handleCallback(Handler.java:739) 
     at android.os.Handler.dispatchMessage(Handler.java:95) 
     at android.os.Looper.loop(Looper.java:211) 
     at android.app.ActivityThread.main(ActivityThread.java:5371) 
     at java.lang.reflect.Method.invoke(Native Method) 
     at java.lang.reflect.Method.invoke(Method.java:372) 
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:945) 
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:740)

看來，我遇到的問題是同一個這樣一個問題：SugarORM in AndroidManifest。但該解決方案僅適用於碎片。有沒有其他方法可以從活動中獲得正確的上下文？

來源

2015-10-21 user1749623

這個面臨同樣的問題在這裏的任何解決方案.. –

com.orm.SugarApp不能轉換到 id.ac.ui.presentronik.activity.MainActivity

通行證在getActivity（）作爲上下文：

ContentResolver.requestSync(getActivity().getAccount(), AccountHelper.AUTHORITY, settingsBundle);

OR

ContentResolver.requestSync(((com.orm.SugarApp) getApplicationContext()).getAccount(), AccountHelper.AUTHORITY, settingsBundle);

記住你的清單中你設置了這樣的東西：

<application 
    android:allowBackup="true" 
    android:icon="@mipmap/ic_launcher" 
    android:label="@string/app_name" 
    android:theme="@style/AppTheme" 
    tools:replace="android:icon" 
    android:name="com.orm.SugarApp">

您還需要使用這些權限：

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

來源

2017-08-17 17:24:25

Sugar ORM：嘗試從getApplicationContext（）轉換上下文時出現類轉換異常

回答

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