I am trying to access the
public static List<ChatThread> Chat_list of my ChatThread Class
from the run() method of my Client Class but i keep getting an empty array(Infact it throws an exception at that point : Exception in thread "Thread-2" java.lang.NullPointerException)
and am very certain that that arrayList exists and is not empty(Because i did a test on the arrayList in my ChatThread Class). Just take a look at my code. Please I need your help on what to do.
Thanks.
This is the class containing the arrayList :
public class ChatThread extends Thread {
private Socket sc;
private String cherry_name;
private String passwd;
public static List<ChatThread> Chat_list = new ArrayList<ChatThread>(); //THE STATIC ARRAY LIST
private BufferedReader br;
private BufferedWriter bw;
public ChatThread(Socket sc){
try {
this.sc=sc;
System.out.println(sc);
br = new BufferedReader(new InputStreamReader(sc.getInputStream()));
bw = new BufferedWriter(new OutputStreamWriter(sc.getOutputStream()));
String help = br.readLine();
this.cherry_name=help.split("@")[0];
this.passwd=help.split("@")[1];
System.out.println(this.cherry_name);
System.out.println(this.passwd);
Chat_list.add(this); //This is where i add it to the arrayList
if(Chat_list.isEmpty()) //This is where i did the test
System.out.println("I am empty");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void run(){
//Comparaison of information with that in the database
try{
bw.write("success");
bw.newLine();
bw.flush();
while(true){
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public Socket getSc() {
return sc;
}
public String getCherry_name() {
return cherry_name;
}
}
As for the Client class :
public class Client extends Thread {
private Socket socket;
private BufferedReader br;
private BufferedWriter bw;
private ChatThread th;
private String cherry_name;
public Client(String cherry_name,String passwd){
try
{
socket = new Socket("127.0.0.1", 8888);
this.cherry_name=cherry_name;
br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
bw = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
bw.write(cherry_name+"@"+passwd);
bw.newLine();
bw.flush();
}
catch (IOException e) {
// TODO Auto-generated catch block
System.out.println("Erreur lors de la lecture du socket");
e.printStackTrace();
}
}
@SuppressWarnings("deprecation")
public void run()
{
try {
String help = br.readLine();
if(help.equals("failed")){
this.notify();
this.destroy();
socket.close();
}
else{
if(ChatThread.Chat_list.isEmpty()) System.out.println("Empty array!!!"); //This is where it says the array is empty whereas it wasn't the case in the ChatThread Class
for(ChatThread ct : ChatThread.Chat_list){
if(cherry_name.equals(ct.getCherry_name())){
th=ct;
break;
}
}
while(true){
}
}
} catch (IOException e) {
// TODO Auto-generated catch block
System.out.println("Error whilst reading from the socket");
e.printStackTrace();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
System.out.println("Interruption");
e.printStackTrace();
}
}
public Socket getSocket() {
return socket;
}
}
And my server class :
public class Server {
public static void main(String[] args) {
try {
ServerSocket server =new ServerSocket(8888);
Socket sc;
System.out.println("Server Started");
while(true){
sc=server.accept();
System.out.println("New Connection");
new ChatThread(sc).start();
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
A main class to instantiate the Client class :
public class help {
public static void main(String[] argv) {
new Client("Jerry","Smith").start();
}
}