自定义全局应用程序类因“android.app.Application 无法转换为”而中断
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Custom global Application class breaks with "android.app.Application cannot be cast to"
提问by sandalone
I have a custom global class which looks like this
我有一个自定义的全局类，看起来像这样
import android.app.Application;
public class MyApp extends Application {
public String MainAct;
public String getMainAct() {
return MainAct;
}
public void setMainAct(String mainAct) {
MainAct = mainAct;
}
}
I want to preserve a string in this class via another Activityin its onCreatemethod.
我想通过Activity其onCreate方法中的另一个保留此类中的字符串。
String local = "myLocalVariable";
((MyApp) getApplication()).setMainAct(local); //breaks here!!!
String name = ((MyApp) getApplication()).getMainAct();
It breaks on the marked line with error: Caused by: java.lang.ClassCastException: android.app.Application cannot be cast to com.xxx.yyy.global.MyApp
它在标记的行上中断并出现错误： Caused by: java.lang.ClassCastException: android.app.Application cannot be cast to com.xxx.yyy.global.MyApp
I've checked the code for five times and I cannot find error anywhere. Can anyone tell me where the error is?!
我已经检查了五次代码，但在任何地方都找不到错误。谁能告诉我错误在哪里？！
Thanks
谢谢
回答by K-ballo
The error states that the type of the object returned by getApplicationis android.app.Application. A possible cause for this is that you failed to define the application in the manifest. Make sure that your manifest includes something in the lines of:
错误指出返回的对象的类型getApplication是android.app.Application。一个可能的原因是您未能在清单中定义应用程序。确保您的清单包含以下行中的内容：
<application android:name=".MyApp"...
</application>
回答by Val
Another solution for older Android devices or emulators. You defined an application in the manifest:
旧 Android 设备或模拟器的另一种解决方案。您在清单中定义了一个应用程序：
<application
android:name=".MyApp"...
</application>
but you still have this problem?
但是你还有这个问题吗？
Try to disable instant run:
尝试禁用即时运行：
- Disable an Instant run
- Clean and rebuild the project
- Remove the app from device and install it again without Instant run
- 禁用即时运行
- 清理并重建项目
- 从设备中删除应用程序并重新安装，无需即时运行
