Warum funktioniert das BlankFragment nicht?

Question

Ich versuche eine App zu erstellen, die ein Fragment anzeigt, wenn Sie auf eine Option in einer Navigationsleiste klicken. Wenn jedoch eine BlankFragment (unter Verwendung BlankFragment fragment = new BlankFragment(); erstellen, bekomme ich einen Fehler. BlankFragment verwandelt sich in rot und Android Studio erkennt sie nicht

MainActivity.java

... 

    } else if (id == R.id.nav_shooks) { 

     FragmentManager fragmentManager = getFragmentManager(); 

     FragmentTransaction transaction = fragmentManager.beginTransaction(); 

     BlankFragment fragment = new BlankFragment(); 
     transaction.add(R.id.shooksLayout, fragment); 

     transaction.commit(); 

    } else if (id == R.id.nav_prizes) { 

... 

ShooksFragment

package com.shook.android.shook; 

import android.content.Context; 
import android.net.Uri; 
import android.os.Bundle; 
import android.support.v4.app.Fragment; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 


/** 
* A simple {@link Fragment} subclass. 
* Activities that contain this fragment must implement the 
* {@link ShooksFragment.OnFragmentInteractionListener} interface 
* to handle interaction events. 
*/ 
public class ShooksFragment extends Fragment { 

    private OnFragmentInteractionListener mListener; 

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


    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
          Bundle savedInstanceState) { 
     // Inflate the layout for this fragment 
     return inflater.inflate(R.layout.fragment_shooks, container, false); 
    } 

    // TODO: Rename method, update argument and hook method into UI event 
    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; 
    } 

    /** 
    * This interface must be implemented by activities that contain this 
    * fragment to allow an interaction in this fragment to be communicated 
    * to the activity and potentially other fragments contained in that 
    * activity. 
    * <p/> 
    * See the Android Training lesson <a href= 
    * "http://developer.android.com/training/basics/fragments/communicating.html" 
    * >Communicating with Other Fragments</a> for more information. 
    */ 
    public interface OnFragmentInteractionListener { 
     // TODO: Update argument type and name 
     void onFragmentInteraction(Uri uri); 
    } 
} 

Here is the error. As you can see, the word BlankFragment is in red

Answer 1

Sie sind in der ShooksFragment die newInstance() Methode fehlt,

Fügen Sie diese Methode hinzu und melden Sie sich bitte erneut.

// TODO: Rename and change types and number of parameters 
public static ShooksFragment newInstance() { 

    ShooksFragment fragment = new ShooksFragment(); 

    return fragment; 
} 

EDIT:

Da Sie ShooksFragment innerhalb MainActivity laden möchten, können Sie einfach ein Objekt der ShooksFragment machen und dieses Fragment laden Sie das Fragment Manager.

... 

    } else if (id == R.id.nav_shooks) { 

     FragmentManager fragmentManager = getFragmentManager(); 

     FragmentTransaction transaction = fragmentManager.beginTransaction(); 

     ShooksFragment fragment = new ShooksFragment(); 
     transaction.add(R.id.shooksLayout, fragment); 

     transaction.commit(); 

    } else if (id == R.id.nav_prizes) { 

...