拋出ClassCastException上MyFirstApp

Question

這是第一次我會在教程如何使用以下URL創建Android上的應用程序：MyFirstApp

當我跑了，我得到了我的堆棧跟蹤一個ClassCastException通過logcat的這看起來像這樣：

03-02 13:18:49.365: E/AndroidRuntime(1996): FATAL EXCEPTION: main 
03-02 13:18:49.365: E/AndroidRuntime(1996): java.lang.IllegalStateException: Could not execute method of the activity 
03-02 13:18:49.365: E/AndroidRuntime(1996):  at android.view.View$1.onClick(View.java:3044) 
03-02 13:18:49.365: E/AndroidRuntime(1996):  at android.view.View.performClick(View.java:3511) 
03-02 13:18:49.365: E/AndroidRuntime(1996):  at android.view.View$PerformClick.run(View.java:14105) 
03-02 13:18:49.365: E/AndroidRuntime(1996):  at android.os.Handler.handleCallback(Handler.java:605) 
03-02 13:18:49.365: E/AndroidRuntime(1996):  at android.os.Handler.dispatchMessage(Handler.java:92) 
03-02 13:18:49.365: E/AndroidRuntime(1996):  at android.os.Looper.loop(Looper.java:137) 
03-02 13:18:49.365: E/AndroidRuntime(1996):  at android.app.ActivityThread.main(ActivityThread.java:4424) 
03-02 13:18:49.365: E/AndroidRuntime(1996):  at java.lang.reflect.Method.invokeNative(Native Method) 
03-02 13:18:49.365: E/AndroidRuntime(1996):  at java.lang.reflect.Method.invoke(Method.java:511) 
03-02 13:18:49.365: E/AndroidRuntime(1996):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) 
03-02 13:18:49.365: E/AndroidRuntime(1996):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) 
03-02 13:18:49.365: E/AndroidRuntime(1996):  at dalvik.system.NativeStart.main(Native Method) 
03-02 13:18:49.365: E/AndroidRuntime(1996): Caused by: java.lang.reflect.InvocationTargetException 
03-02 13:18:49.365: E/AndroidRuntime(1996):  at java.lang.reflect.Method.invokeNative(Native Method) 
03-02 13:18:49.365: E/AndroidRuntime(1996):  at java.lang.reflect.Method.invoke(Method.java:511) 
03-02 13:18:49.365: E/AndroidRuntime(1996):  at android.view.View$1.onClick(View.java:3039) 
03-02 13:18:49.365: E/AndroidRuntime(1996):  ... 11 more 
03-02 13:18:49.365: E/AndroidRuntime(1996): Caused by: java.lang.ClassCastException: com.android.internal.view.menu.ActionMenuItemView cannot be cast to android.widget.TextView 
03-02 13:18:49.365: E/AndroidRuntime(1996):  at com.example.myfirstapp.MainActivity.sendMessage(MainActivity.java:34) 
03-02 13:18:49.365: E/AndroidRuntime(1996):  ... 14 more 

這是引用類MainActivity中的sendMessage（View視圖）方法。最初它看起來像這樣：

public void sendMessage(View view) 
{ 
    Intent intent = new Intent(this, DisplayMessageActivity.class); 
    EditText editText = (EditText) findViewById(R.id.edit_message); 
    String message = editText.getText().toString(); 
    intent.putExtra(EXTRA_MESSAGE, message); 
    startActivity(intent); 
} 

但是，這引起了相同的ClassCastException問題。在我的研究中，我偶然發現了這篇文章： http://code.google.com/p/android/issues/detail?id=32941

哪些狀態我應該用TextView對象更改EditText對象。我做到了。所以現在我的方法是這樣的：

public void sendMessage(View view) 
{ 
    Intent intent = new Intent(this, DisplayMessageActivity.class); 
    //EditText editText = (EditText) findViewById(R.id.edit_message); 
    TextView tView = (TextView)findViewById(R.id.edit_message); 
    String message = tView.getText().toString(); 
    intent.putExtra(EXTRA_MESSAGE, message); 
    startActivity(intent); 
} 

編譯得很好。但是我仍然得到了與stacktrace日誌中所述的相同的ClassCastException。我不知道如何解決這個問題。請指教。

艾倫

Answer 1

在你res/layout/activity_main.xml（它的默認佈局文件，它可以在不同的項目命名），有什麼的edit_message類型？

它應該是相同的一個在你的施法(TextView)findViewById(R.id.edit_message);。