Android IllegalStateException 在 (GlobalApp) getApplication() 转换时抛出

Question

我收到以下消息时崩溃了:

04-17 11:18:19.855: W/dalvikvm(368): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
04-17 11:18:19.925: E/AndroidRuntime(368): FATAL EXCEPTION: main
04-17 11:18:19.925: E/AndroidRuntime(368): java.lang.IllegalStateException: Could not execute method of the activity
04-17 11:18:19.925: E/AndroidRuntime(368):  at android.view.View$1.onClick(View.java:2072)
04-17 11:18:19.925: E/AndroidRuntime(368):  at android.view.View.performClick(View.java:2408)
04-17 11:18:19.925: E/AndroidRuntime(368):  at android.view.View$PerformClick.run(View.java:8816)
04-17 11:18:19.925: E/AndroidRuntime(368):  at android.os.Handler.handleCallback(Handler.java:587)
04-17 11:18:19.925: E/AndroidRuntime(368):  at android.os.Handler.dispatchMessage(Handler.java:92)
04-17 11:18:19.925: E/AndroidRuntime(368):  at android.os.Looper.loop(Looper.java:123)
04-17 11:18:19.925: E/AndroidRuntime(368):  at android.app.ActivityThread.main(ActivityThread.java:4627)
04-17 11:18:19.925: E/AndroidRuntime(368):  at java.lang.reflect.Method.invokeNative(Native Method)
04-17 11:18:19.925: E/AndroidRuntime(368):  at java.lang.reflect.Method.invoke(Method.java:521)
04-17 11:18:19.925: E/AndroidRuntime(368):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
04-17 11:18:19.925: E/AndroidRuntime(368):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
04-17 11:18:19.925: E/AndroidRuntime(368):  at dalvik.system.NativeStart.main(Native Method)
04-17 11:18:19.925: E/AndroidRuntime(368): Caused by: java.lang.reflect.InvocationTargetException
04-17 11:18:19.925: E/AndroidRuntime(368):  at com.UturpatShuPepper.LogCat.TheLogCatActivity.onGo(TheLogCatActivity.java:41)
04-17 11:18:19.925: E/AndroidRuntime(368):  at java.lang.reflect.Method.invokeNative(Native Method)
04-17 11:18:19.925: E/AndroidRuntime(368):  at java.lang.reflect.Method.invoke(Method.java:521)
04-17 11:18:19.925: E/AndroidRuntime(368):  at android.view.View$1.onClick(View.java:2067)
04-17 11:18:19.925: E/AndroidRuntime(368):  ... 11 more
04-17 11:18:19.925: E/AndroidRuntime(368): Caused by: java.lang.ClassCastException: android.app.Application
04-17 11:18:19.925: E/AndroidRuntime(368):  ... 15 more

我跟着调试器，看到崩溃发生在以下代码中，在标记的行中:

// Go button pressed
public void onGo(View v) {
    final EditText et = (EditText) findViewById(R.id.filters);
    String filter = "food\\s+[ABC]";
    if(!ValidateText(et, "^\\s*(" + filter + "(\\s+)" + filter + ")?$", "Bad filters")) {
        return;
    }
--->GlobalApp app = (GlobalApp) getApplication(); <--- CRASHES HERE
    for(int i = 0; i &lt; 100; i++) {
       app.addMessage("message number " + i);
    }

根据日志，这是由 ClassCastException 引起的。

我定义了 GlobalApp 类如下:

public class GlobalApp extends Application {

private final ArrayList<String> messages = new ArrayList<String>();

public ArrayList<String> getMessages(){
    return messages;
}

public void addMessage(String msg){
    messages.add(msg);
}
}

为什么转换错误？正确的做法是什么？

Answer 1

在你的 list 中改变这个

<application android:icon="@drawable/icon" android:label="@string/app_name">

这个

<application android:icon="@drawable/icon" android:label="@string/app_name" android:name=".GlobalApp">

因为您没有说明操作系统的 android:name 查找默认的 Application 类。为了将它指向您的 Application 子类，您应该使用 android:name 属性。