TabActivity未恢复

Question

我正在开发一个应用程序，在这个应用程序中，我在扩展选项卡活动的类下创建了一个数据库。但是，当我的选项卡活动恢复时，我的应用程序就会崩溃。任何帮助都将不胜感激。

这里是我的代码

public class MainActivity extends TabActivity {
    /** Called when the activity is first created. */
    public static   boolean paid=false;
    public String num;
    public String num1;
    public String  name;
    static int delay;
    public static Boolean fromapp=false;
    SQLiteDatabase db;
    TabHost tabHost;

    @SuppressWarnings("deprecation")
    @SuppressLint("NewApi")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);



    Toast.makeText(getApplicationContext(), String.valueOf(fromapp), Toast.LENGTH_SHORT).show();    
        Resources res = getResources(); // Resource object to get Drawables
        tabHost = getTabHost();  // The activity TabHost
        TabHost.TabSpec spec;  // Resusable TabSpec for each tab
        Intent intent;  // Reusable Intent for each tab

        // Create an Intent to launch an Activity for the tab (to be reused)

      /*  
        intent = new Intent().setClass(this, DialPad.class);
        spec = tabHost.newTabSpec("DIAL PAD").setIndicator("DIAL PAD",res.getDrawable(R.drawable.ic_launcher)).setContent(intent);
        tabHost.addTab(spec);*/


        intent = new Intent().setClass(this, Calllog.class);
        spec = tabHost.newTabSpec("CALL LOG").setIndicator("CALL LOG",res.getDrawable(R.drawable.ic_launcher)).setContent(intent);
        tabHost.addTab(spec);

        intent = new Intent().setClass(this, Contacts.class);
        spec = tabHost.newTabSpec("CONTACTS").setIndicator("CONTACTS",res.getDrawable(R.drawable.ic_launcher)).setContent(intent);
        tabHost.addTab(spec);


        db=openOrCreateDatabase("Mydb", MODE_PRIVATE, null);
        db.execSQL("CREATE TABLE IF NOT EXISTS Fromapp(delay INTEGER);");

        Cursor c=db.rawQuery("select * from Fromapp", null);


        if(c.moveToFirst())
        {
        }
        else
        {
            db.execSQL("insert into Fromapp values("+5000+")");
        }



 }





    @Override
     public boolean onOptionsItemSelected(MenuItem item)
     {

            switch (item.getItemId())
            {
            case R.id.ten:
                db.execSQL("update Fromapp set delay="+10000);


                return true;
            case R.id.twenty:
                db.execSQL("update Fromapp set delay="+20000);


                return true;
            case R.id.fifty:
                db.execSQL("update Fromapp set delay="+30000);


                return true;    
            case R.id.hundred:
                db.execSQL("update Fromapp set delay="+40000);
                return true;
            case R.id.twohundred:
                db.execSQL("update Fromapp set delay="+50000);
                return true;
            case R.id.fivehundred:
                db.execSQL("update Fromapp set delay="+60000);
                return true;    

            default:

                return super.onOptionsItemSelected(item);
            }
        }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
    @Override
    protected void onResume() {
        // TODO Auto-generated method stub
        super.onResume();       
    }

My LogCat显示了下面的

11-01 12:28:49.513: E/AndroidRuntime(32547): FATAL EXCEPTION: main
11-01 12:28:49.513: E/AndroidRuntime(32547): java.lang.RuntimeException: Unable to resume activity {com.thoughtrix.tryamisscall/com.thoughtrix.tryamisscall.MainActivity}: android.database.StaleDataException: Attempted to access a cursor after it has been closed.
11-01 12:28:49.513: E/AndroidRuntime(32547):    at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2742)
11-01 12:28:49.513: E/AndroidRuntime(32547):    at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2771)
11-01 12:28:49.513: E/AndroidRuntime(32547):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1276)
11-01 12:28:49.513: E/AndroidRuntime(32547):    at android.os.Handler.dispatchMessage(Handler.java:99)
11-01 12:28:49.513: E/AndroidRuntime(32547):    at android.os.Looper.loop(Looper.java:137)
11-01 12:28:49.513: E/AndroidRuntime(32547):    at android.app.ActivityThread.main(ActivityThread.java:5041)
11-01 12:28:49.513: E/AndroidRuntime(32547):    at java.lang.reflect.Method.invokeNative(Native Method)
11-01 12:28:49.513: E/AndroidRuntime(32547):    at java.lang.reflect.Method.invoke(Method.java:511)
11-01 12:28:49.513: E/AndroidRuntime(32547):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
11-01 12:28:49.513: E/AndroidRuntime(32547):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
11-01 12:28:49.513: E/AndroidRuntime(32547):    at dalvik.system.NativeStart.main(Native Method)
11-01 12:28:49.513: E/AndroidRuntime(32547): Caused by: android.database.StaleDataException: Attempted to access a cursor after it has been closed.
11-01 12:28:49.513: E/AndroidRuntime(32547):    at android.database.BulkCursorToCursorAdaptor.throwIfCursorIsClosed(BulkCursorToCursorAdaptor.java:64)
11-01 12:28:49.513: E/AndroidRuntime(32547):    at android.database.BulkCursorToCursorAdaptor.requery(BulkCursorToCursorAdaptor.java:133)
11-01 12:28:49.513: E/AndroidRuntime(32547):    at android.database.CursorWrapper.requery(CursorWrapper.java:186)
11-01 12:28:49.513: E/AndroidRuntime(32547):    at android.app.Activity.performRestart(Activity.java:5148)
11-01 12:28:49.513: E/AndroidRuntime(32547):    at android.app.ActivityThread.performRestartActivity(ActivityThread.java:3214)
11-01 12:28:49.513: E/AndroidRuntime(32547):    at android.app.LocalActivityManager.moveToState(LocalActivityManager.java:168)
11-01 12:28:49.513: E/AndroidRuntime(32547):    at android.app.LocalActivityManager.dispatchResume(LocalActivityManager.java:523)
11-01 12:28:49.513: E/AndroidRuntime(32547):    at android.app.ActivityGroup.onResume(ActivityGroup.java:61)
11-01 12:28:49.513: E/AndroidRuntime(32547):    at com.thoughtrix.tryamisscall.MainActivity.onResume(MainActivity.java:134)
11-01 12:28:49.513: E/AndroidRuntime(32547):    at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1185)
11-01 12:28:49.513: E/AndroidRuntime(32547):    at android.app.Activity.performResume(Activity.java:5182)
11-01 12:28:49.513: E/AndroidRuntime(32547):    at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2732)
11-01 12:28:49.513: E/AndroidRuntime(32547):    ... 10 more

Answer 1

我最终找到了答案。这个异常经常会弹出，因为我的calllog类中有"managedQuery“。我过去常常在使用managedQuery检索数据之后显式地关闭游标。绝不能这样做。当光标完成时，您的活动将自动关闭它。

Answer 2

试着打开数据库

db.getWritableDatabase();
db.open();