如何在此AsynTask类中实现onProgressUpdate方法

Question

我正在使用网络扫描程序，为此我使用AsyncTask类将扫描发送到后台。但是我在实现onProgressUpdate（）方法时遇到了问题。我将类型为String的ArrayList传递给TaskScanNetwork类。该阵列将包含网络上所有生命主机的列表。任何帮助赞赏。感谢

package com.example.android.droidscanner;

import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.lang.reflect.Array;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

    Button btnRead;
    Button btnScan;
    TextView textResult;

    ListView listViewNode;
    ArrayList<Node> listNote;
    ArrayList<String> listNetwork;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btnRead = (Button)findViewById(R.id.readhost);
        btnScan = (Button) findViewById(R.id.readnet);
        textResult = (TextView)findViewById(R.id.result);

        listViewNode = (ListView)findViewById(R.id.nodelist);
        listNote = new ArrayList<>();
        listNetwork = new ArrayList<>();

        //initidating adapter for host only
        ArrayAdapter<Node> adapterHost = new ArrayAdapter<Node>(
                MainActivity.this,
                android.R.layout.simple_list_item_1,
                listNote);
        listViewNode.setAdapter(adapterHost);

        //initiating adapter for network scan
        ArrayAdapter<String> adapterNetwork = new ArrayAdapter(
                MainActivity.this,
                android.R.layout.simple_list_item_1,
                listNetwork);
        listViewNode.setAdapter(adapterNetwork);


        btnRead.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                new TaskReadAddresses(listNote, listViewNode).execute();
            }
        });

        btnRead.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                new TaskScanNetwork(listNetwork, listViewNode).execute();
            }
        });
    }


    private class TaskReadAddresses extends AsyncTask<Void, Node, Void> {

        ArrayList<Node> array;
        ListView listView;

        TaskReadAddresses(ArrayList<Node> array, ListView v){
            listView = v;
            this.array = array;
            array.clear();
            textResult.setText("querying...");
        }

        @Override
        protected Void doInBackground(Void... params) {
            readAddresses();
            return null;
        }

        @Override
        protected void onPostExecute(Void aVoid) {
            textResult.setText("Done");
        }

        @Override
        protected void onProgressUpdate(Node... values) {
            listNote.add(values[0]);
            ((ArrayAdapter)(listView.getAdapter())).notifyDataSetChanged();
        }

        private void readAddresses() {
            BufferedReader bufferedReader = null;

            try {
                bufferedReader = new BufferedReader(new FileReader("/proc/net/arp"));

                String line;
                while ((line = bufferedReader.readLine()) != null) {
                    String[] splitted = line.split(" +");
                    if (splitted != null && splitted.length >= 4) {
                        String ip = splitted[0];
                        String mac = splitted[3];
                        if (mac.matches("..:..:..:..:..:..")) {
                            Node thisNode = new Node(ip, mac);
                            publishProgress(thisNode);
                        }
                    }
                }

            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally{
                try {
                    bufferedReader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    /*
    * Asynctask to scan the network
    * */
    private class TaskScanNetwork extends AsyncTask<Void, ArrayList<String>, Void> {

        String network;
        ListView listView;
        String lowBoundIp;
        ArrayList<String> allNetwork;

        TaskScanNetwork(ArrayList<String> array, ListView v){
            listView = v;
            allNetwork = array;
            textResult.setText("Scanning...");
        }

        @Override
        protected Void doInBackground(Void... params) {
            scanNetwork();
            return null;
        }

        @Override
        protected void onPostExecute(Void aVoid) {
            textResult.setText("Done");
        }

        @Override
        protected void onProgressUpdate(ArrayList<String>... values) {
            allNetwork.add(values);
            ((ArrayAdapter)(listView.getAdapter())).notifyDataSetChanged();
        }

        private void scanNetwork() {
            try {
                InetAddress localHost = InetAddress.getLocalHost();
                lowBoundIp = localHost.getHostAddress();
                int lastDot = lowBoundIp.lastIndexOf(".");
                String host = lowBoundIp.substring(0, lastDot);
                Process ping;
                for(int i = 1; i < 255; i++) {
                    host = host + "." + Integer.toString(i);
                    try {
                        ping = Runtime.getRuntime().exec("ping -n 1 " + host);
                        int returnVal = ping.waitFor();
                        if(returnVal == 0) {
                            publishProgress(allNetwork);
                        }
                    }
                    catch(Exception ex) {
                        ex.printStackTrace();
                    }
                }
            }  catch (UnknownHostException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}