Q: How to change fragment using Android studio navigation drawer Hi can someone help me changing fragments using navigation drawer I tried some guides here none of them work 
Here's my code 
@Override
public void onNavigationDrawerItemSelected(int position) {
    // update the main content by replacing fragments
    Fragment fragment;
    FragmentManager fragmentManager = getSupportFragmentManager(); // For AppCompat use getSupportFragmentManager


    switch(position) {
        default:
        case 0:
            fragment = PlaceholderFragment.newInstance(position + 1);
            break;
        case 1:
            fragment = new profile_fragment();
            break;
    }
    fragmentManager.beginTransaction()
            .replace(R.id.container, fragment)
            .commit();

    fragmentManager.beginTransaction()
            .replace(R.id.container, fragment)
            .commit();
}

I want to add this fragment but I always get an error when click the 2nd item from the navigation drawer
          package com.the.healthescort;

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



  public class profile_fragment extends Fragment {
  // TODO: Rename parameter arguments, choose names that match
  // the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
  private static final String ARG_PARAM1 = "param1";
  private static final String ARG_PARAM2 = "param2";

  // TODO: Rename and change types of parameters
  private String mParam1;
  private String mParam2;

  private OnFragmentInteractionListener mListener;

 /**
 * 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 profile_fragment.
 */
  // TODO: Rename and change types and number of parameters
  public static profile_fragment newInstance(String param1, String param2) {
    profile_fragment fragment = new profile_fragment();
    Bundle args = new Bundle();
    args.putString(ARG_PARAM1, param1);
    args.putString(ARG_PARAM2, param2);
    fragment.setArguments(args);
    return fragment;
}

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

@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 rootView = inflater.inflate(R.layout.fragment_profile_fragment, container, false);
    return rootView;
}

// 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(Activity activity) {
    super.onAttach(activity);
    try {
        mListener = (OnFragmentInteractionListener) activity;
    } catch (ClassCastException e) {
        throw new ClassCastException(activity.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
    public void onFragmentInteraction(Uri uri);
}
}


A: You don't implement  OnFragmentInteractionListener( in profile_fragment)  in your MainActivity. Because your MainActivity call profile_fragment.
So you need to implement the listener OnFragmentInteractionListener in your MainActivity. Like that:
    public class MainActivity extends ActionBarActivity
    implements profile_fragment.OnFragmentInteractionListener {

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


A: *

*use this method for replacing fragmnet : 
public void selectItem(int position) {
    switch (position) {
    case 0:
    Fragment fr2 = fragmentManager.findFragmentByTag("orders");

        if (fr2 == null) {
            fragmentManager
                    .beginTransaction()
                    .replace(R.id.sellers_frame_container,
                            new Sellers_Orders_Fragment(), "orders")
                    .commit();
        } else {
            fragmentManager.beginTransaction().show(fr2).commit();
        }
        break;


    case 1:


        Fragment fr3 = fragmentManager.findFragmentByTag("add_product");

        if (fr3 == null) {
            fragmentManager
                    .beginTransaction()
                    .replace(R.id.sellers_frame_container,
                            new Sellers_Add_Product_Fragment(),
                            "add_product").commit();
        } else {
            fragmentManager.beginTransaction().show(fr3).commit();
        }

        break;


    }
}


*Call this method on listview item click that is in your navigation drawer.
litview.onItemclickListener(.....){
selectItem(postion);
}
