"This field leaks a context object"?

各位好，跟著安卓training文檔做，在一個(gè)繼承AsyncTask的子類聲明了一個(gè)TextView私有變量，為什么提示This field leaks a context object?如何消除這個(gè)警告？Stackoverflow上沒(méi)有這方面解答。

package com.example.bob.simpleasynctask;

import android.os.AsyncTask;
import android.widget.TextView;

import java.util.Locale;
import java.util.Random;

/**
 * Created by bob on 2018/3/22.
 */

public class SimpleAsynccTask extends AsyncTask<Void,Void,String> {

    //這里提示有警告
    private TextView mTextView;
    public SimpleAsynccTask(TextView tv){
        this.mTextView=tv;
    }
    @Override
    protected String doInBackground(Void... voids) {
        Random random=new Random();
        int n=random.nextInt(10);

        int sleepTime=n*100;

        try {
            Thread.sleep(sleepTime);
        } catch (InterruptedException ex){
            ex.printStackTrace();
        }

        return String.format(new Locale("en-us"),"Awake at last after sleeping for %d milliseconds.",sleepTime);
    }

    @Override
    protected void onProgressUpdate(Void... voids) {
        super.onProgressUpdate(voids);
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
    }

    @Override
    protected void onPostExecute(String s) {
        mTextView.setText(s);
    }
}

詳細(xì)信息：

對(duì)了，能請(qǐng)教一下各位as里怎么復(fù)制錯(cuò)誤/警告信息呢？