public void doClick(View v){

switch(v.getId()){

  case R.id.network:

  if(isNetWorkConnected(MainActivity.this)==true){Toast.makeText().....}

  case :

}

}

 public boolean isNetWorkConnected(Context context){//以上下文做完参数

   if(context!=null){

     ConnectivityManager mConnectivityManager=(ConnectivityManager)context.getSystemService(CONNECTIVITY_SERVICE);

     NetworkInfo mNetWorkInfo=mConnectivityManager.getActiveNetworkInfo();

   if(mNetWorkInfo!=null){

     return mNetWorkInfo.isAvailable();

   }

 }

  return false;//未连接返回false

}