1つのフラグメントを別のフラグメントにアンドロイドで移動するには

Question

私はアプリケーションにフラグメントを含んでいます。 1つのフラグメントを別のフラグメントに移動することはできません。

私はそれが動作していない、このコード（android value passing from fragment to fragment using recyclerview not workingから参照）

SpeedDialFragment fragobj = new SpeedDialFragment(); 
    Bundle bundle=new Bundle(); 
    bundle.putString("message", "From Activity"); 
    fragobj.setArguments(bundle); 
    switchFragment(R.layout.fragment_page, fragobj); 

を使用します。

マイコードを以下に示します。

MainActivityのJava：

public class MainActivity extends AppCompatActivity implements PageFragment.OnFragmentInteractionListener { 
    ViewPager viewPage; 
    @Override protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     initView(); 
     startService(new Intent(this, LockScreenService.class)); 
    } 

    private void initView() { 
     initViewPager(); 
    } 

    private void initViewPager() { 
     viewPage = (ViewPager) this.findViewById(R.id.viewpage); 
     viewPage.setOffscreenPageLimit(3); 
     viewPage.setCurrentItem(1); 
     viewPage.setAdapter(new FragmentStatePagerAdapter(getSupportFragmentManager()) { 
      @Override public Fragment getItem(int position) { 
       if (position < 2) { 
        return PageFragment.newInstance("", ""); 
       } else { 
        return new AmapFragment(); 
       } 
      } 

      @Override public int getCount() { 
       return 3; 
      } 
     }); 
    } 

    @Override public void onFragmentInteraction(Uri uri) { 
    } 

    public void loadFragment(int id, Fragment fragment) { 
     FragmentTransaction ft = getSupportFragmentManager().beginTransaction(); 
     ft.replace(id, fragment, fragment.toString()); 
     ft.addToBackStack(null); 
     ft.commit(); 
    } 
    } 

activity_main.xml

<?xml version="1.0" encoding="utf-8"?> 
    <RelativeLayout 
    xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:tools="http://schemas.android.com/tools" 
    android:id="@+id/activity_main" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    tools:context="com.happiness.lockscreen.MainActivity" 
    > 
    <android.support.v4.view.ViewPager 
    android:id="@+id/viewpage" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    ></android.support.v4.view.ViewPager> 
    </RelativeLayout> 

fragment_page.xml

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" 
xmlns:tools="http://schemas.android.com/tools" 
android:layout_width="match_parent" 
android:layout_height="match_parent" 
> 
<Button 
    android:text="Speed Dial" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:id="@+id/buttonSpeedDial" /> 
</FrameLayout> 

PageFragment.java

public class PageFragment extends Fragment { 
    private static final String ARG_PARAM1 = "param1"; 
    private static final String ARG_PARAM2 = "param2"; 
    private String mParam1; 
    private String mParam2; 

    Button button; 
    Context context; 

    private OnFragmentInteractionListener mListener; 
    public PageFragment() { 

    } 

    public static PageFragment newInstance(String param1, String param2) { 
    PageFragment fragment = new PageFragment(); 
    Bundle args = new Bundle(); 
    args.putString(ARG_PARAM1, param1); 
    args.putString(ARG_PARAM2, param2); 
    fragment.setArguments(args); 
    return fragment; 
    } 

    @Override public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    if (getArguments() != null) { 
     mParam1 = getArguments().getString(ARG_PARAM1); 
     mParam2 = getArguments().getString(ARG_PARAM2); 
    } 
    } 

    @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, 
     Bundle savedInstanceState) { 
    // Inflate the layout for this fragment 


    View view = inflater.inflate(R.layout.fragment_page, container, false); 

    button = (Button) view.findViewById(R.id.buttonSpeedDial); 

    button.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
     Log.d("SpeedDialFragment", "clicked : "); 
     /*SpeedDialFragment fragment = new SpeedDialFragment(); // replace your custom fragment class 
     Bundle bundle = new Bundle(); 
     FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction(); 
     bundle.putString("key","value"); // use as per your need 
     fragment.setArguments(bundle); 
     fragmentTransaction.addToBackStack(null); 
     fragmentTransaction.replace(viewID,fragment); 
     fragmentTransaction.commit();*/ 

     SpeedDialFragment fragobj = new SpeedDialFragment(); 
     Bundle bundle=new Bundle(); 
     bundle.putString("message", "From Activity"); 
     fragobj.setArguments(bundle); 
     switchFragment(R.layout.fragment_page, fragobj); 
     } 
    }); 
    return view; 
    } 
    public void switchFragment(int id, Fragment fragment) { 
    if (context == null) 
     return; 
    if (context instanceof MainActivity) { 
     MainActivity mainActivity = (MainActivity) context; 
     mainActivity.loadFragment(id, fragment); 
    } 
    } 
    public void onButtonPressed(Uri uri) { 
    if (mListener != null) { 
     mListener.onFragmentInteraction(uri); 
    } 
    } 

    @Override public void onAttach(Context context) { 
    super.onAttach(context); 
    if (context instanceof OnFragmentInteractionListener) { 
     mListener = (OnFragmentInteractionListener) context; 
    } else { 
     throw new RuntimeException(
      context.toString() + " must implement OnFragmentInteractionListener"); 
    } 
    } 

    @Override public void onDetach() { 
    super.onDetach(); 
    mListener = null; 
    } 

    public interface OnFragmentInteractionListener { 
    // TODO: Update argument type and name 
    void onFragmentInteraction(Uri uri); 
    } 
} 

私を助けてください。

SpeedDialFragment.java 
public class SpeedDialFragment extends Fragment { 
private static final String ARG_PARAM1 = "param1"; 
private static final String ARG_PARAM2 = "param2"; 
private String mParam1; 
private String mParam2; 

private OnFragmentInteractionListener mListener; 

public SpeedDialFragment() { 
    // Required empty public constructor 
} 

/** 
* Use this factory method to create a new instance of 
* this fragment using the provided parameters. 
* 
* @param param1 Parameter 1. 
* @param param2 Parameter 2. 
* @return A new instance of fragment PageFragment. 
*/ 
// TODO: Rename and change types and number of parameters 
public static PageFragment newInstance(String param1, String param2) { 
    PageFragment fragment = new PageFragment(); 
    Bundle args = new Bundle(); 
    args.putString(ARG_PARAM1, param1); 
    args.putString(ARG_PARAM2, param2); 
    fragment.setArguments(args); 
    return fragment; 
} 

@Override public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    if (getArguments() != null) { 
     mParam1 = getArguments().getString(ARG_PARAM1); 
     mParam2 = getArguments().getString(ARG_PARAM2); 
    } 
} 

@Override public View onCreateView(LayoutInflater inflater, ViewGroup container, 
            Bundle savedInstanceState) { 

    String strtext=getArguments().getString("message"); 
    Log.d("SpeedDialFragment", "strtext : "+strtext); 
    // Inflate the layout for this fragment 
    return inflater.inflate(R.layout.fragment_speeddial, container, false); 
} 

public void onButtonPressed(Uri uri) { 
    if (mListener != null) { 
     mListener.onFragmentInteraction(uri); 
    } 
} 

@Override public void onAttach(Context context) { 
    super.onAttach(context); 
    if (context instanceof OnFragmentInteractionListener) { 
     mListener = (OnFragmentInteractionListener) context; 
    } else { 
     throw new RuntimeException(
       context.toString() + " must implement OnFragmentInteractionListener"); 
    } 
} 

@Override public void onDetach() { 
    super.onDetach(); 
    mListener = null; 
} 


*/ 
public interface OnFragmentInteractionListener { 
    // TODO: Update argument type and name 
    void onFragmentInteraction(Uri uri); 
} 
} 

Answer 1

if(context==null) return;コンテキストオブジェクトを初期化していません。 試用版

public void switchFragment(int id, Fragment fragment) { 

    if (getActivity() instanceof MainActivity) { 
     MainActivity mainActivity = (MainActivity) getActivity(); 
     mainActivity.loadFragment(id, fragment); 
    } 
}