How do you findout if the values of varables have changed in a class

Question

Hey Hey,
I have a number of classes which contain varables. I need a way of knowing if the values of the varables have changed. so i can do a job. is there a easy way of finding this out maybe by hash or size?
ive worked out i can get a array of all the fields in the class like this
         Field[] fields = cls.getDeclaredFields();

Answer 1

Well, usually you do build support for this kind of stuff into the class itself. I usually do it by using Java's PropertyChange stuff:
import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;
public class ChangeReporter {
  private final PropertyChangeSupport pcs;
  private int field;
  public ChangeReporter() {
    pcs = new PropertyChangeSupport(this);
  public void setField( final int newValue ) {
    if (newValue != field) {
      pcs.firePropertyChange("field", field, field = newValue);
  public void addPropertyChangeListener( final PropertyChangeListener pcl ) {
    if (pcl != null) {
      pcs.addPropertyChangeSupport(pcl);
}For additional information see the relevant API documentation.