導航屏幕

Question

我在導航屏幕時遇到了一個小問題，實際上我通過菜單按鈕創建一個事件來顯示SD卡中文件的內容。每當菜單被點擊時，運行時異常發生我已經附上了我的代碼，錯誤日誌和xml。任何幫助將不勝感激。

菜單按鈕操作 //處理菜單按鈕

public boolean onKeyUp(int keyCode, KeyEvent event) { 
     if (keyCode == KeyEvent.KEYCODE_MENU) { 

      startActivity(new Intent(ContactListActivity1.this,App2Activity.class)); 
      finish(); 


     } 

    return true; 
} 

App2Activity.java

public class App2Activity extends ContactListActivity1 { 


    @Override 
    public void onCreate(Bundle savedInstanceState) { 

     super.onCreate(savedInstanceState); 
     setContentView(R.layout.file_view); 


      File sdcard= Environment.getExternalStorageDirectory(); 
      File dir = new File(sdcard.getAbsolutePath() + "/dir1/dir2"); 

      File file = new File(dir, "my_group.txt"); 

      StringBuilder text = new StringBuilder(); 
      try { 
       BufferedReader br = new BufferedReader(new FileReader(file)); 
       String line; 

       while ((line = br.readLine()) != null) { 
        text.append(line); 
        text.append('\n'); 

       } 
      } 
      catch (IOException e) { 

       e.printStackTrace(); 


      } 


      TextView tv = (TextView)findViewById(R.id.text_view);     
      tv.setText(text); 

    } 

} 

file_view.xml

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout 
    xmlns:android="http://schemas.android.com/apk/res/android" 
    android:orientation="vertical" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" 
> 
<TextView 

    android:id="@+id/text_view" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" 
    /> 




</LinearLayout> 

錯誤日誌

09-04 13:51:33.680: W/CursorWrapperInner(25536): Cursor finalized without prior close() 
09-04 13:51:33.880: I/System.out(25536): Am I Coming here !! 
09-04 13:51:33.900: D/AndroidRuntime(25536): Shutting down VM 
09-04 13:51:33.900: W/dalvikvm(25536): threadid=1: thread exiting with uncaught exception (group=0x409961f8) 
09-04 13:51:33.940: E/AndroidRuntime(25536): FATAL EXCEPTION: main 
09-04 13:51:33.940: E/AndroidRuntime(25536): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.contactlistactivity1/com.example.contactlistactivity1.App2Activity}: java.lang.RuntimeException: Your content must have a ListView whose id attribute is 'android.R.id.list' 
09-04 13:51:33.940: E/AndroidRuntime(25536): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1955) 
09-04 13:51:33.940: E/AndroidRuntime(25536): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980) 
09-04 13:51:33.940: E/AndroidRuntime(25536): at android.app.ActivityThread.access$600(ActivityThread.java:122) 
09-04 13:51:33.940: E/AndroidRuntime(25536): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146) 
09-04 13:51:33.940: E/AndroidRuntime(25536): at android.os.Handler.dispatchMessage(Handler.java:99) 
09-04 13:51:33.940: E/AndroidRuntime(25536): at android.os.Looper.loop(Looper.java:137) 
09-04 13:51:33.940: E/AndroidRuntime(25536): at android.app.ActivityThread.main(ActivityThread.java:4340) 
09-04 13:51:33.940: E/AndroidRuntime(25536): at java.lang.reflect.Method.invokeNative(Native Method) 
09-04 13:51:33.940: E/AndroidRuntime(25536): at java.lang.reflect.Method.invoke(Method.java:511) 
09-04 13:51:33.940: E/AndroidRuntime(25536): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) 
09-04 13:51:33.940: E/AndroidRuntime(25536): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) 
09-04 13:51:33.940: E/AndroidRuntime(25536): at dalvik.system.NativeStart.main(Native Method) 
09-04 13:51:33.940: E/AndroidRuntime(25536): Caused by: java.lang.RuntimeException: Your content must have a ListView whose id attribute is 'android.R.id.list' 
09-04 13:51:33.940: E/AndroidRuntime(25536): at android.app.ListActivity.onContentChanged(ListActivity.java:243) 
09-04 13:51:33.940: E/AndroidRuntime(25536): at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:254) 
09-04 13:51:33.940: E/AndroidRuntime(25536): at android.app.Activity.setContentView(Activity.java:1835) 
09-04 13:51:33.940: E/AndroidRuntime(25536): at com.example.contactlistactivity1.App2Activity.onCreate(App2Activity.java:20) 
09-04 13:51:33.940: E/AndroidRuntime(25536): at android.app.Activity.performCreate(Activity.java:4465) 
09-04 13:51:33.940: E/AndroidRuntime(25536): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049) 
09-04 13:51:33.940: E/AndroidRuntime(25536): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1919) 
09-04 13:51:33.940: E/AndroidRuntime(25536): ... 11 more 

Answer 1

您正在使用ListActivity。所以ListActivity期待您的內容查看有一個ListView控件ID爲@android:id/list

所以更改XML下面

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout 
    xmlns:android="http://schemas.android.com/apk/res/android" 
    android:orientation="vertical" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" 
> 
<TextView 

    android:id="@+id/text_view" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" 
    /> 
<ListView android:id="@android:id/list" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:background="#00FF00" 
    android:layout_weight="1" 
    android:drawSelectorOnTop="false"/>  
</LinearLayout>