在片段中，实例不会被保存

Question

请查看以下代码

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTransaction;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.RadioGroup.OnCheckedChangeListener;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;
import android.widget.TextView;
import android.widget.Toast;

public class InputFragment extends Fragment {


    private SeekBar daysAsCustomerSeek;

    private View view;

    //Following variables will save the application state and load back
    //on resume

    private final String DAYS_AS_CUSTOMER_VALUE_HOLDER = "days as customer value";




    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
    {
        //Intializing instance variables
        view = inflater.inflate(R.layout.input, container,false);



        daysAsCustomerSeek = (SeekBar)view.findViewById(R.id.days_as_customer_seekbar);

        //Set default max values
        daysAsCustomerSeek.setMax(210);

        return view;

    }

    //This method will save the instances
    @Override
    public void onSaveInstanceState(Bundle savedInstanceStateBundle)
    {

        savedInstanceStateBundle.putInt(DAYS_AS_CUSTOMER_VALUE_HOLDER, daysAsCustomerSeek.getProgress());


    }

    //This method will restore the instances
    @Override 
    public void onActivityCreated(Bundle savedInstanceStateBundle)
    {
        super.onActivityCreated(savedInstanceStateBundle);

        if(savedInstanceStateBundle!=null)
        {

            daysAsCustomerSeek.setProgress(savedInstanceStateBundle.getInt(DAYS_AS_CUSTOMER_VALUE_HOLDER));

        }
    }

}

问题是当我转动设备或导航回到这个片段时，其状态未被保存！相反，一切都被重建了！为什么是这样？为什么这段代码没有显示状态？

Answer 1

添加：

super.onSaveInstanceState(savedInstanceStateBundle);

在onSaveInstanceState方法中。

Answer 2

someFragment.setRetainInstance(true);