读取所有的android应用显示在Item中，按键有响应

public class MainActivity extends Activity implements OnItemClickListener {

private GridView mGridView;
private Context mContext;
private PackageManager mPackageManager;
private List<ResolveInfo> mAllApps;
List<String> packagelist=new ArrayList<String>();
List<String> systemApp=new ArrayList<String>();
HashMap<String, String[]> map=new HashMap<String, String[]>();

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
setupViews();
}

public void setupViews(){
mContext = MainActivity.this;
mGridView = (GridView)findViewById(R.id.allapps);  //用以显示读取到的应用
mPackageManager = getPackageManager();  //包管理器

Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);
mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);

mAllApps = mPackageManager.queryIntentActivities(mainIntent, 0);  //得到所有的APP
Collections.sort(mAllApps, new ResolveInfo.DisplayNameComparator(mPackageManager));  //排序

mGridView.setAdapter(new GridItemAdapter(mContext, mAllApps));  //显示设置
mGridView.setNumColumns(3);  //显示列数
mGridView.setOnItemClickListener(this);  //设置Click监听
}

public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
ResolveInfo res = mAllApps.get(position);
String pkg = res.activityInfo.packageName;
String cls = res.activityInfo.name;
ComponentName componet = new ComponentName(pkg, cls);
Intent i = new Intent();
i.setComponent(componet);
startActivity(i);
}

private class GridItemAdapter extends BaseAdapter{
private Context context;
private List<ResolveInfo> resInfo;

public GridItemAdapter(Context c,List<ResolveInfo> res){
context = c;
resInfo = res;
}

public int getCount() {
return resInfo.size();
}

public Object getItem(int position) {
return null;
}

public long getItemId(int position) {
return 0;
}

public View getView(int position, View convertView, ViewGroup parent) {
convertView = LayoutInflater.from(context).inflate(R.layout.application_layout, null);
ImageView app_icon = (ImageView)convertView.findViewById(R.id.app_icon);
TextView app_tilte = (TextView)convertView.findViewById(R.id.app_title);

ResolveInfo res = resInfo.get(position);
app_icon.setImageDrawable(res.loadIcon(mPackageManager));
app_tilte.setText(res.loadLabel(mPackageManager).toString());

if((res.activityInfo.applicationInfo.flags&ApplicationInfo.FLAG_SYSTEM)<=0){
String packagename=res.loadLabel(mPackageManager).toString();
String[] permission;
try {
//获取已安装应用的权限
permission = mPackageManager.getPackageInfo(res.activityInfo.packageName, PackageManager.GET_PERMISSIONS).requestedPermissions;
packagelist.add(packagename);
map.put(packagename, permission);
}catch (NameNotFoundException e) {
e.printStackTrace();
}
}
return convertView;
}
}
}