title: gridview NullPointerException simpleAdapter
body: <pre><code>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&lt;View&gt; aList;
      private Adapter_homeViewPager mAdapter;
  
      //GridView
      private GridView gridview;
      private Context mcontext = this.getActivity();
      private List&lt;Map&lt;String,Object&gt;&gt; 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&lt;View&gt;();
          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&lt;&gt;();
          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 &lt; imgIds.length; i++) {
              Map&lt;String, Object&gt; showitem = new HashMap&lt;String, Object&gt;();
              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;
      }
  }
  </code></pre>
  
  <p>Exception :</p>
  
  <pre><code>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.&lt;init&gt;(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 
  </code></pre>