The 4th assignment of Computer Network: My Routing Protocol

MyRoutingProto.java

import java.net.*;
//net.InetAddress;
//net.DatagramPacket;
//net.DatagramSocket;
import java.util.*;
import java.io.*;
//io.File;

class Receiving extends Thread {
    //constructor
    private String ipAddr;
    private String broadcastAddr;
    
    public Receiving(String ia, String ba) {
        ipAddr = ia;
        broadcastAddr = ba; 
    }
    public void run() {
        try {
            System.out.println("Begin Receiving!");
            //keep receiving
            //receive data
            byte[] buffer = new byte[65535];
            DatagramSocket receiver = new DatagramSocket(12001);
            DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
            while(true) {   
                receiver.receive(packet);   
                String stringBuffer = new String(packet.getData(), 0, packet.getLength());
                
                //deal only when receive non-self packet    
                if(!stringBuffer.equals(MyRoutingProto.tempString)) {
                    //System.out.println("received: " + stringBuffer);//Should not be printed if run on one machine
                    
                    //update native table
                    String[] info = stringBuffer.split(":");
                    //info[0] is "hello", info[3] is useless sequence number
                    if(!MyRoutingProto.disTable.containsKey(info[1])) {
                        MyRoutingProto.disTable.put(info[1], new Integer(1));
                    } else {//existed!!!
                        if(new Integer(1).compareTo(MyRoutingProto.disTable.get(info[1])) == -1) {
                            MyRoutingProto.disTable.put(info[1], new Integer(1));
                        }
                    }

                        //iterately the String[] to deal with the left part: 0.itself, 1.add non-existed, 2.compare to the existed ones
                    for(int i = 3; i <= info.length - 1; i++) {
                        //!!forgot to add 1!!!
                        String[] keyValue = info[i].split(",");
                        if(ipAddr.equals(keyValue[0])) {
                            //0: pass itself
                            //do nothing
                        } else if(!MyRoutingProto.disTable.containsKey(keyValue[0])) {
                            //1
                            MyRoutingProto.disTable.put(keyValue[0], Integer.valueOf(Integer.valueOf(keyValue[1]).intValue() + 1));
                        } else {
                            //2
                            if(Integer.valueOf((Integer.valueOf(keyValue[1]).intValue() + 1)).compareTo(MyRoutingProto.disTable.get(keyValue[0])) == -1) {
                                //update, write directly
                                MyRoutingProto.disTable.put(keyValue[0], Integer.valueOf(Integer.valueOf(keyValue[1]).intValue() + 1));
                            }
                        }
                    }

                    StringBuffer sf = new StringBuffer();
                    //Show the new table
                    System.out.println("** My table: " + ipAddr + " **");
                    sf.append("** My table: " + ipAddr + " **");
                    sf.append("\n");
                    Iterator iterator = MyRoutingProto.disTable.keySet().iterator();
                    while(iterator.hasNext()) {
                        Object key = iterator.next();
                        System.out.println("   -- " + String.valueOf(key) +  " -- " + MyRoutingProto.disTable.get(key));
                        sf.append("   -- " + String.valueOf(key) +  " -- " + MyRoutingProto.disTable.get(key));
                        sf.append("\n");
                    }
                    //Print new table
                    File file = new File("/tmp/topo_" + ipAddr + ".out");
                    FileWriter fw = new FileWriter(file);
                    fw.write(sf.toString(), 0, sf.length());
                    fw.close();
                }
            }
        } catch(Exception e) {
            System.out.println(e);
        }
    }
}
class Broadcasting extends Thread{
    private String ipAddr;
    private String broadcastAddr;
    public Broadcasting(String ia, String ba) {
        ipAddr = ia;
        broadcastAddr = ba;
    }
    public void run() {
        //loop and cast every 10 minutes;
        System.out.println("Begin Broadcasting!");
        int i = 1;
        try {
            DatagramSocket sender = new DatagramSocket();
            sender.setBroadcast(true);//function unknown
            
            byte[] data = null;
            /*
            String str1 = "1234";
            String str2 = "";
            byte[] b;
            
            b = str1.getBytes();
            str2 = String.valueOf(b);
            */          
            //data = i.toString().getBytes();   
            
            /*
            String s = String.valueOf(i);
            String s = Integer.toString(i);
            */

            while(true) {
                String stringData = "hello:" + ipAddr + ":" + i;
                Iterator iterator = MyRoutingProto.disTable.keySet().iterator();
                while(iterator.hasNext())
                {
                    Object key = iterator.next();
                    stringData += ":" + String.valueOf(key) + "," + MyRoutingProto.disTable.get(key);
                }
                //System.out.println("sent: " + stringData);
                MyRoutingProto.tempString = stringData;
                
                data = stringData.getBytes();

                //build the packet, content: data
                DatagramPacket packet = new DatagramPacket(data, data.length, InetAddress.getByName(broadcastAddr), 12001);
            
                sender.send(packet);
                i++;
                Thread.sleep(10000);
            }
        
        } catch(Exception e) {
            System.out.println(e);
        }
    }
}
public class MyRoutingProto {
    public static HashMap<String, Integer> disTable;
    public static String tempString;

    public static void main(String[] args) {
        //System.out.println("Hello World!");

        disTable = new HashMap<String, Integer>();
        tempString = null;

        String localAddr = null;
        if (args.length != 2)
        {
            System.out.println("Must input the IP and broadcast Address!");
            return;
        }
        String ipAddr = args[0];
        String broadcastAddr = args[1];
        /*  
        try {
            //remark
            //getByName():return InetAddress by hostname, //or ip?
            //getByAddress(byte[] addr)
            InetAddress local = InetAddress.getLocalHost();//Return InetAddress of Local
            localAddr = local.getHostAddress();
            System.out.println("MyRoutingPro for " + localAddr + " start!");
        } catch(Exception e) {
            System.out.println("Unknown Host!");
        }
        if (!localAddr.equals(ipAddr))
        {
            System.out.println("Wrong IP Address!");
            return; 
        }
        */
        try {
            //create second thread for keep receiving String
            new Receiving(ipAddr, broadcastAddr).start();
            //Create one thread for broadcast every 10 seconds
            new Broadcasting(ipAddr, broadcastAddr).start();
        } catch(Exception e) {
            System.out.println("Create thread wrong!");
        }
    }
}