Concurrent Access does not modify an attribute

Question

Good day,
I'm working on a multi-process environment, whose main class could be summed up as this:
public Class ServerCluster {
     // In reality, this attribute belongs to a superior class and is protected
     private SolverCluster solverCluster;
     public void installSolver (SolverCluster newSolverCluster){
          // Tests here to check the newSolverCluster isn't null
          sychronized (this){
               System.out.println("A new SolverCluster is given");
               this.SolverCluster = newSolverCluster;
     public void mainProcess(){
          while (true){
               synchronized (this){
                    if (this.solverCluster != null){
                         System.out.println("the solverCluster isn't null");
                         //That's where we want to go
               thread.sleep(1000);
}Basically, a process started from another class calls the method mainProcess and then stays inside.
Then, another Java process connects to the serverCluster (by RMI) and calls the method installSolver.
The problem is that the message "A solverCluster is given" is displayed, but when the process leaves the method, the attribute becomes null again and therefore the message "the solverCluster isn't null" in the mainProcess method is never displayed.
(I'm using NetBeans 4.1.).
Thank you

Answer 1

Basically, a process started from another class calls
the method mainProcess and then stays inside.Okay it loops checking then sleeping. Fine.
Then, another Java process connects to the
serverCluster (by RMI) and calls the method
installSolver.Presumably this is the same serverCluster object
The problem is that the message "A solverCluster is
given" is displayed, but when the process leaves the
method, the attribute becomes null again and
therefore the message "the solverCluster isn't null"
in the mainProcess method is never displayed.
(I'm using NetBeans 4.1.).My best guess would be that they are different serverCluster objects.
Does the real code use instances or statics? If statics you'd have to watch for classes being loaded in different classloaders and therefore having their own static values.