如何判斷rssi高於一定值發出提醒視窗以及震動

我需要在RSSI值大於一定值時
傳送一個"a"給HC-06
請問該如何做到這個
以下是我的程式碼

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package com.example.user.blue1;

import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;

public class BLEListViewAdapter extends RecyclerView.Adapter<BLEListViewAdapter.ViewHolder>{
 //數據集
private List<BLEObj> mList = new ArrayList<>();
OnItemClickListener onItemClickListener;
public void setOnItemClickListener(OnItemClickListener onItemClickListener) {
this.onItemClickListener = onItemClickListener;
}
public interface OnItemClickListener{
void onClick(int position, BLEObj obj);
}
public class ViewHolder extends RecyclerView.ViewHolder{
TextView tv_device_name;
TextView tv_device_address;
TextView tv_device_rssi;
TextView tv_device_distance;
TextView tv_device_timestamp;
TextView btn_connect;
View view;


public ViewHolder(View itemView) {
super(itemView);
view = itemView;
tv_device_name = (TextView) itemView.findViewById(R.id.tv_device_name);
tv_device_address = (TextView) itemView.findViewById(R.id.tv_device_address);
tv_device_rssi = (TextView) itemView.findViewById(R.id.tv_device_rssi);
tv_device_distance = (TextView) itemView.findViewById(R.id.tv_device_distance);
tv_device_timestamp = (TextView) itemView.findViewById(R.id.tv_device_timestamp);
btn_connect = (TextView) itemView.findViewById(R.id.btn_connect);

btn_connect.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
onItemClickListener.onClick(getPosition(), mList.get(getPosition()));
}
});
}
}

@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.listitem, null);
return new ViewHolder(itemView);
}

@Override
public void onBindViewHolder(ViewHolder holder, int position) {
holder.tv_device_name.setText("" + mList.get(position).getDevice().getName());
holder.tv_device_address.setText("裝置位址:" + mList.get(position).getAddress());

int rssi = Math.abs(mList.get(position).getRssi());
if (rssi >= 0 && rssi < 70){
holder.tv_device_rssi.setText("信號強度RSSI(dBm):-" + rssi);
holder.tv_device_rssi.setTextColor(holder.view.getContext().getResources().getColor(R.color.distance_high));
}else if (rssi >= 70 && rssi < 120){
holder.tv_device_rssi.setText("信號強度RSSI(dBm):-" + rssi);
holder.tv_device_rssi.setTextColor(holder.view.getContext().getResources().getColor(R.color.distance_mid));
}else if (rssi >= 120){
holder.tv_device_rssi.setText("信號強度RSSI(dBm):-" + rssi);
holder.tv_device_rssi.setTextColor(holder.view.getContext().getResources().getColor(R.color.distance_low));
}else {
holder.tv_device_rssi.setText("信號強度RSSI(dBm):-" + rssi);
holder.tv_device_rssi.setTextColor(holder.view.getContext().getResources().getColor(R.color.distance_low));
}

holder.tv_device_distance.setText("計算距離:" + calculateDistance(rssi) + "米");
holder.tv_device_timestamp.setText("掃描時間:" + mList.get(position).getTimestamp());

if (mList.get(position).isConnected() == true) {
holder.btn_connect.setText("斷開");
holder.btn_connect.setTextColor(holder.view.getContext().getResources().getColor(R.color.device_connected));
}else {
holder.btn_connect.setText("連接");
holder.btn_connect.setTextColor(holder.view.getContext().getResources().getColor(R.color.device_disconnected));
}
}
@Override
public int getItemCount() {
return mList.size();
}

private float calculateDistance(int rssi){
//手持: 79.119 12.02
//平放: 72.496 12.012
float power = (float) ((rssi - 79.119)/(12.02));
return (float) Math.pow(Math.E, power);
}

public void setDatas(Map<String, BLEObj> map){
mList.clear();
for (String key : map.keySet()) {
mList.add(map.get(key));
}
this.notifyDataSetChanged();
}
}