微调框无法在Android中保存其状态

Question

I can't find a way to save the state of a spinner using the SharedPreferences`. The code i use is this one:

mIo = (Spinner) view.findViewById(R.id.schedulerSpinner);
mIo.setSelection(preferences.getInt("spinnerSelection",0));
String[] availableIo = {"one", "two", "three", "four"};
ArrayAdapter<CharSequence> adapter = new ArrayAdapter<CharSequence>(getActivity(),android.R.layout.simple_spinner_item, availableIo);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
mIo.setAdapter(adapter);
mIo.setOnItemSelectedListener(new OnItemSelectedListener() {

    public void onItemSelected(AdapterView<?> arg0, View view, int position, long id) {
        int item = mIo.getSelectedItemPosition();

        String selected = mIo.getItemAtPosition(position).toString();
        Toast.makeText(this, "Selected item: " + selected, Toast.LENGHT_SHORT).show();
        editor = preferences.edit();
        editor.putInt("spinnerSelection", item);
        editor.commit();

    }
    public void onNothingSelected(AdapterView<?> arg0) {

     }
});

when i click the item i want it goes well and the toast display the item correctly, but if i close and re open the app the spinner shows the first item and not which i have selected before.. I tryied different ways but with no results. Thanks

Answer 1

The reason it is updating to first position is because you are setting the item before setting the adapter to spinner at that time there are no values in spinner so you calling setSelection() makes no difference, because new values are set in spinner by adapter. update your code like below

mIo = (Spinner) view.findViewById(R.id.schedulerSpinner);
String[] availableIo = {"one", "two", "three", "four"};
ArrayAdapter<CharSequence> adapter = new ArrayAdapter<CharSequence>(getActivity(),android.R.layout.simple_spinner_item, availableIo);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
mIo.setAdapter(adapter);
//SET SELECTION AFTER YOU SET THE ADAPTER NOT BEFORE IT
mIo.setSelection(preferences.getInt("spinnerSelection",0));
mIo.setOnItemSelectedListener(new OnItemSelectedListener() {

    public void onItemSelected(AdapterView<?> arg0, View view, int position, long id) {
        int item = mIo.getSelectedItemPosition();

        String selected = mIo.getItemAtPosition(position).toString();
        Toast.makeText(this, "Selected item: " + selected, Toast.LENGHT_SHORT).show();
        editor = preferences.edit();
        editor.putInt("spinnerSelection", item);
        editor.commit();

    }
    public void onNothingSelected(AdapterView<?> arg0) {

     }
});