動態隱藏片段（Viewpager和片段）

Question

我正在使用viewpager並滾動片段。 我想隱藏偏好更改的片段

package app.converto;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.SharedPreferences.OnSharedPreferenceChangeListener;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.view.ViewPager;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Toast;
import app.converto.settings.SettingsActivity;
import app.converto.ui.LengthFragment;
import app.converto.ui.TemperatureFragment;

public class ConverTo extends FragmentActivity /*implements OnClickListener*/ implements OnSharedPreferenceChangeListener {

    SectionsPagerAdapter mSectionsPagerAdapter; //declaring pageradapter class 
    ViewPager mViewPager; // declaring viewpager class


    private TemperatureFragment fragment2;
    private LengthFragment fragment1;
    private static final int RESULT_SETTINGS = 1;

    @Override
    public void onCreate(Bundle savedInstanceState) { //methods to call on app launch 
        super.onCreate(savedInstanceState);

        mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
        setContentView(R.layout.converto_home);  
        mViewPager = (ViewPager) findViewById(R.id.pager);  
        mViewPager.setAdapter(mSectionsPagerAdapter);

        PreferenceManager.setDefaultValues(this, R.xml.preferences, false);

        SharedPreferences sharedPref = PreferenceManager.getDefaultSharedPreferences(this);
        sharedPref.registerOnSharedPreferenceChangeListener(this);
        //boolean prefTemperature = sharedPref.getBoolean("prefTemperature", true);



    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {

        case R.id.menu_settings:
            Intent i = new Intent(this, SettingsActivity.class);
            startActivityForResult(i, RESULT_SETTINGS);
            break;

        }

        return true;
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        switch (requestCode) {
        case RESULT_SETTINGS:
            showUserSettings();
            break;

        }

    }


    private void showUserSettings() {
        SharedPreferences sharedPrefs = PreferenceManager
                .getDefaultSharedPreferences(this);

        StringBuilder builder = new StringBuilder();

        builder.append(
                sharedPrefs.getBoolean("pref_temperature", true));
        builder.append(
                sharedPrefs.getBoolean("pref_length", false));

        builder.append(
                sharedPrefs.getBoolean("pref_area", false));



    //  TextView settingsTextView = (TextView) findViewById(R.id.textUserSettings);

    //  settingsTextView.setText(builder.toString());
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.settings, menu);
        return true;
    }


    public class SectionsPagerAdapter extends FragmentPagerAdapter {




        public SectionsPagerAdapter(FragmentManager fm) {
            super(fm);
        }

        @Override
        public Fragment getItem(int i) {
            switch(i){
            case 0:
                 fragment2 = new TemperatureFragment(ConverTo.this);  

                return fragment2;

            case 1:
                  fragment1 = new LengthFragment(ConverTo.this);  
                return fragment1;
            }
            return null;
        }

        @Override
        public int getCount() {
            return 2;
        }

        @Override
        public CharSequence getPageTitle(int position) {
            switch (position) {
                case 0: return getString(R.string.heading_temperature);
                case 1: return getString(R.string.heading_length);
            }
            return null;
        }
    }


    public void onSharedPreferenceChanged(SharedPreferences arg0, String key) {
        if (key.equals("prefTemperature")) {
            Toast.makeText(this, "here!", Toast.LENGTH_LONG).show();  

            FragmentManager fM = getSupportFragmentManager();
            FragmentTransaction fT = fM.beginTransaction();
            fT.hide(fragment1);
            fT.commit();
        }
    }

    }

這是我得到的錯誤04-07 21：30：14.313：E / AndroidRuntime（15363）：java.lang.IllegalStateException：在onSaveInstanceState之后無法執行此操作

這是我的temperatureFragment代碼

package app.converto.ui;

import java.text.DecimalFormat;
import java.util.ArrayList;
import java.util.List;

import android.annotation.SuppressLint;
import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.Spinner;
import app.converto.R;
import app.converto.utils.Temperature;

@SuppressLint("ValidFragment")
public class TemperatureFragment extends Fragment implements OnClickListener, OnItemSelectedListener {

     EditText rInputTemp;
     public static String rSelectedUnit;
     Spinner spinner;
     List<String> rValues = new ArrayList<String>();
     Temperature rTemperature;
     Context rContext;
     ListView rResultsList;

     public TemperatureFragment(Context context) {
         rContext = context;

    }
     public TemperatureFragment(){

     }

     public Context getContext(){
         return rContext;
     }

    @Override  
    public void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
    } 
     @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {

         View view = inflater.inflate(R.layout.view_temperature, container, false);  
         rInputTemp = (EditText) view.findViewById(R.id.inputTemp);



         rInputTemp.setText("1");

         rInputTemp.addTextChangedListener(new TextWatcher(){
                public void afterTextChanged(Editable s) {
                    if(s.toString().equals("")){

                    }
                    else{


                    rTemperature = new Temperature(spinner.getSelectedItemPosition(), Double.parseDouble(s.toString()));        
                    setDisplayText(rTemperature.getValues());
                    }
                }
                public void beforeTextChanged(CharSequence s, int start, int count, int after){}
                public void onTextChanged(CharSequence s, int start, int before, int count){}
            });

         rResultsList = (ListView) view.findViewById(R.id.results);
         spinner = (Spinner) view.findViewById(R.id.temp_units);


         spinner.setOnItemSelectedListener(this);
         ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(getActivity().getApplicationContext(), R.array.units_temperature,R.layout.spinner_layout);
         adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
         spinner.setAdapter(adapter);
         adapter.setDropDownViewResource(R.layout.spinner_layout);

        return view;
    }// end oncreate

    public void onClick(View v) {



    }
    public void onItemSelected(AdapterView<?> p, View arg1, int pos,
            long id) {
        rSelectedUnit = p.getItemAtPosition(pos).toString();

        rTemperature = new Temperature(spinner.getSelectedItemPosition(), Double.parseDouble(rInputTemp.getText().toString()));
        setDisplayText(rTemperature.getValues());

    }//spinneronItemSelected

    public void onNothingSelected(AdapterView<?> p) {

    }//spinner onNothingSelected

    double roundfourDecimals(double d) {
        DecimalFormat fourDForm = new DecimalFormat("#.####");
    return Double.valueOf(fourDForm.format(d));
    }



    private void setDisplayText(List<String> values){


        ArrayAdapter<String> adapter2 = new ArrayAdapter<String>(rContext, R.layout.result,R.id.result,values);
        rResultsList.setAdapter(adapter2);


    }


}//end fragment 2

Answer 1

將我的評論轉到答案：

您必須將fT.commit()更改為fT.commitAllowingStateLoss()因為當Activity在后台時，此代碼可能會運行，在這種情況下，您不允許commit() 。