gridview NullPointerException simpleAdapter

package com.rong.shop.myshop.home;

import android.content.Context;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.support.v4.view.ViewPager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.SimpleAdapter;

import com.rong.shop.R;    
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * Created by Administrator on 2016/8/13.
 */
public class MyFragment_home extends Fragment {

    //ViewPager
    private ViewPager vpager_one;
    private ArrayList<View> aList;
    private Adapter_homeViewPager mAdapter;

    //GridView
    private GridView gridview;
    private Context mcontext = this.getActivity();
    private List<Map<String,Object>> listitem;
    private SimpleAdapter gAdapter;
    private int[] imgIds;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fg_home, container, false);

        //ViewPager
        vpager_one = (ViewPager) view.findViewById(R.id.vpager);

        aList = new ArrayList<View>();
        LayoutInflater li = getLayoutInflater(null);
        aList.add(li.inflate(R.layout.fg_home_viewpager_view_1, null, false));
        aList.add(li.inflate(R.layout.fg_home_viewpager_view_2, null, false));
        aList.add(li.inflate(R.layout.fg_home_viewpager_view_3, null, false));
        aList.add(li.inflate(R.layout.fg_home_viewpager_view_4, null, false));
        aList.add(li.inflate(R.layout.fg_home_viewpager_view_5, null, false));

        mAdapter = new Adapter_homeViewPager(aList);
        vpager_one.setAdapter(mAdapter);    

        //GridView
        gridview = (GridView)view.findViewById(R.id.gridview);

        listitem= new ArrayList<>();
        imgIds = new int[]{
                R.drawable.fg_home_gridview_1, R.drawable.fg_home_gridview_2,
                R.drawable.fg_home_gridview_3, R.drawable.fg_home_gridview_4,
                R.drawable.fg_home_gridview_5, R.drawable.fg_home_gridview_6,
                R.drawable.fg_home_gridview_7, R.drawable.fg_home_gridview_8,
        };
        for (int i = 0; i < imgIds.length; i++) {
            Map<String, Object> showitem = new HashMap<String, Object>();
            showitem.put("image", imgIds[i]);
            listitem.add(showitem);
        }

        gAdapter = new SimpleAdapter(mcontext, listitem, R.layout.fg_home_gridview_item,
                new String[] { "image" }, new int[]{R.id.gridview_image});
        gridview.setAdapter(gAdapter);   

        return view;
    }
}

Exception :

E/AndroidRuntime: FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.rong.shop/com.rong.shop.myshop.home.MainActivity}: java.lang.NullPointerException
   at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2212)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2271)
    at android.app.ActivityThread.access$800(ActivityThread.java:144)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1205)
     at android.os.Handler.dispatchMessage(Handler.java:102)
     at android.os.Looper.loop(Looper.java:136)
   at android.app.ActivityThread.main(ActivityThread.java:5146)
    at java.lang.reflect.Method.invokeNative(Native Method)
      at java.lang.reflect.Method.invoke(Method.java:515)
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:732)
   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:566)
    at dalvik.system.NativeStart.main(Native Method)
                                                      Caused by: java.lang.NullPointerException
     at android.widget.SimpleAdapter.<init>(SimpleAdapter.java:85)
    at com.rong.shop.myshop.home.MyFragment_home.onCreateView(MyFragment_home.java:75)
    at android.support.v4.app.Fragment.performCreateView(Fragment.java:2074)
    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1286)
     at 
    android.support.v4.app.BackStackRecord.run(BackStackRecord.java:758)
       at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1671)
        at android.support.v4.app.FragmentController.execPendingActions(FragmentController.java:388)
        at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:619)
      at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1171)
      at android.app.Activity.performStart(Activity.java:5241)
     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2178)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2271) 
   at 

android.app.ActivityThread.access$800(ActivityThread.java:144) 
      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1205) 
    at android.os.Handler.dispatchMessage(Handler.java:102) 
     at android.os.Looper.loop(Looper.java:136) 
     at android.app.ActivityThread.main(ActivityThread.java:5146) 
       at 

You are initializing mcontext in the Fragment instantiation, with a call to getActivity. Well there is no Activity yet at that point, so mcontext is null, therefore your SimpleAdapter fails.
You should get rid of mcontext altogether, as it is not needed, and can only cause issues. Just use getActivity instead. So just change it to;

gAdapter = new SimpleAdapter(getActivity(), listitem, R.layout.fg_home_gridview_item, new String[] { "image" }, new int[]{R.id.gridview_image});