multithreading - Do something at variable change in Java -

i want following: specific variable (roomname) changes value, title of jframe should changed new value of roomname. problem is, jframe built before roomname changes.

this little snippet of connection.java class:

public connection() {     ...     fieldname.addkeylistener(new keylistener() {         public void keypressed(keyevent e) {             if(e.getkeychar() == keyevent.vk_enter) {                 setname();             }         }     }); }  public void setname(){     chatframe.frame.setvisible(true);     chatframe.roomname = fieldname.gettext();     this.dispose(); } 

the other class chatframe.java should described action above. need listener or thread this? what's best way it?

one simple solution springs mind wrap variable object, setter method can this:

public void setnewvalue(string newval) {     if(!newval.equals(currentval)) {         currentval = newval;         // value has changed. call relevant code.     } }