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我想存儲一個文件的一些數據,然後從EditTextPreference中取一個值並將其設置爲另一個,它看起來很簡單,但不幸的是我總是有一個FC: EditTextPreference prixtotal =(EditTextPreference)findPreference(「total_prix」);無法設置EditTextPreference [ForceClose]
EditTextPreference prixtotal = (EditTextPreference) findPreference("total_prix");
if ((CheckboxAir==true) && (CheckboxHuile==true) && (CheckboxCarburant==true))
{
data_vidange = date + ": " + km + "km" + " " + prix + "dt"+ " " + " F.Air" + " F.Huile" + " F.Carburant" + "\n";
MyIO.WriteSettings(context,fileDir+fileName, data_vidange);
prixtotal.setText(prix);
}
的logcat:
08-17 21:08:39.677: ERROR/AndroidRuntime(386): FATAL EXCEPTION: main
08-17 21:08:39.677: ERROR/AndroidRuntime(386): java.lang.NullPointerException
08-17 21:08:39.677: ERROR/AndroidRuntime(386): at carburant.android.com.Vidange.onOptionsItemSelected(Vidange.java:109)
08-17 21:08:39.677: ERROR/AndroidRuntime(386): at android.app.Activity.onMenuItemSelected(Activity.java:2205)
08-17 21:08:39.677: ERROR/AndroidRuntime(386): at com.android.internal.policy.impl.PhoneWindow.onMenuItemSelected(PhoneWindow.java:748)
08-17 21:08:39.677: ERROR/AndroidRuntime(386): at com.android.internal.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:143)
08-17 21:08:39.677: ERROR/AndroidRuntime(386): at com.android.internal.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:855)
08-17 21:08:39.677: ERROR/AndroidRuntime(386): at com.android.internal.view.menu.IconMenuView.invokeItem(IconMenuView.java:532)
08-17 21:08:39.677: ERROR/AndroidRuntime(386): at com.android.internal.view.menu.IconMenuItemView.performClick(IconMenuItemView.java:122)
08-17 21:08:39.677: ERROR/AndroidRuntime(386): at android.view.View$PerformClick.run(View.java:9080)
08-17 21:08:39.677: ERROR/AndroidRuntime(386): at android.os.Handler.handleCallback(Handler.java:587)
08-17 21:08:39.677: ERROR/AndroidRuntime(386): at android.os.Handler.dispatchMessage(Handler.java:92)
08-17 21:08:39.677: ERROR/AndroidRuntime(386): at android.os.Looper.loop(Looper.java:123)
08-17 21:08:39.677: ERROR/AndroidRuntime(386): at android.app.ActivityThread.main(ActivityThread.java:3683)
08-17 21:08:39.677: ERROR/AndroidRuntime(386): at java.lang.reflect.Method.invokeNative(Native Method)
08-17 21:08:39.677: ERROR/AndroidRuntime(386): at java.lang.reflect.Method.invoke(Method.java:507)
08-17 21:08:39.677: ERROR/AndroidRuntime(386): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
08-17 21:08:39.677: ERROR/AndroidRuntime(386): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
08-17 21:08:39.677: ERROR/AndroidRuntime(386): at dalvik.system.NativeStart.main(Native Method)
線109是:prixtotal.setText(prix);
任何有問題的根源的想法? 謝謝。