@Override
        public void reload() {
            Material reloadedMat = reloadMaterial(geom.getMaterial());
            // if the reload is successful, we re setup the material with its params and
            // reassign it to the box
            if (reloadedMat != null) {
                geom.setMaterial(reloadedMat);
            }
        }
Will reload the spatial's materials whenever the shader file is changed
on the hard drive
@param shaderName the shader name (relative path to the asset folder or 
to a registered asset path)
@param spat the spatial to reload
jme3-core/src/main/java/com/jme3/util/MaterialDebugAppState.java