Correct way to handle the updated object

Question

Hi,
I have a thread, test2.java, that periodically update a object that pass from test.java. In test.java, the "data" object need to be most updated coz this object is used in other thread also. I can ensure that only test2.java do the write, others threads are read only.
My question is: I can write some dirty code to do what I want. But for a programmer, I want to know the formal, oo way to handle this situation.
Thanks.
Tommy
public class test{
data d;
test2 t2;
public test(){
d = new data(1, getClass().toString());
t2 = new test2(d);
t2.start();
public void runServices(){
while(true){
//If i don't do anything, the following code only print out
//the instance that i init. here.. Not the updated one
System.out.println(d.toString());
try{
Thread.sleep(5000);
}catch(InterruptedException ex){}
public static void main(String[] args){
test t = new test();
t.runServices();
* This class will periodically update the "data" object that
* passed from test.java
public class test2 extends Thread{
int count = 1;
data d;
public test2(data a){
this.d = a;
public void run(){
while(true){
d = new data(count++, getClass().toString());
System.out.println(d.toString());
try{
sleep(5000);
}catch(InterruptedException ex){}
public class data{
int count;
String s = "";
public data(int a, String b){
count = a;
s = b;
public String toString(){
return s + " count:" + count;

Answer 1

Sorry nearly missed that :(
You should try to modify the instance of data you have been given in the constructor for test2 instead of creating a new object:
* This class will periodically update the "data" object that
* passed from test.java
public class test2 extends Thread {
  int count = 1;
  data d;
  public test2(data a) {
    this.d = a;
  public void run() {
    while(true) {
      d.refreshWith(count++, getClass().toString());
      System.out.println(d.toString());
     try {
       sleep(5000);
     } catch(InterruptedException ex){}
}