double dx, dy;    

public void act() {
    ActorA a = (ActorA)getOneIntersectingObject(ActorA.class);

    if(a.getX() > getX()) dx = (Math.abs(getX() - a.getX())/5);
    else dx = ((Math.abs(a.getX() - getX())*-1)/5);
    if(a.getY() > getY()) dy = (Math.abs(getY() - a.getY())/5);
    else dy = ((a.getY() - getY())/5);       

    setLocation(getX() + (int)dx, getY() + (int)dy);
}

/* add an instance Actor field to the Actor1 class */
private Actor actorGrabbed = null;

/* in the 'act' method in the Actor1 class */
// check for initial pressing down of key
if (Greenfoot.isKeyDown("g") && actorGrabbed == null && getOneIntersectingObject(Actor2.class) != null)
{
    // grab the object
    actorGrabbed = (Actor) getOneIntersectingObject(Actor2.class);
    // the rest of this block will avoid the grabbed object from being hidden UNDER the Actor1 objects
    getWorld().removeObject(actorGrabbed);
    getWorld().addObject(actorGrabbed, getX(), getY());
}
// check for actual dragging of the object after moving Actor1 object
if (Greenfoot.isKeyDown("g") && actorGrabbed != null)
{
    // drag the grabbed object
    actorGrabbed.setLocation(getX(), getY());
}
// check for key release
if (!Greenfoot.isKeyDown("g") && actorGrabbed != null)
{
    // release the object
    actorGrabbed = null;
}