抛出ClassCastException上MyFirstApp

Question

这是第一次我会在教程如何使用以下URL创建Android上的应用程序：MyFirstApp

当我跑了，我得到了我的堆栈跟踪一个ClassCastException通过logcat的这看起来像这样：

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 

这是引用类MainActivity中的sendMessage（View视图）方法。最初它看起来像这样：

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，这引起了相同的ClassCastException问题。在我的研究中，我偶然发现了这篇文章： http://code.google.com/p/android/issues/detail?id=32941

哪些状态我应该用TextView对象更改EditText对象。我做到了。所以现在我的方法是这样的：

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); 
} 

编译得很好。但是我仍然得到了与stacktrace日志中所述的相同的ClassCastException。我不知道如何解决这个问题。请指教。

艾伦

Answer 1

在你res/layout/activity_main.xml（它的默认布局文件，它可以在不同的项目命名），有什么的edit_message类型？

它应该是相同的一个在你的施法(TextView)findViewById(R.id.edit_message);。