@Override
    public void setMass(String boneName, float mass) {
        super.setMass(boneName, mass);

        if (getSpatial() != null) {
            PhysicsRigidBody rigidBody;
            if (torsoName.equals(boneName)) {
                rigidBody = torsoLink.getRigidBody();
            } else {
                BoneLink link = findBoneLink(boneName);
                rigidBody = link.getRigidBody();
            }
            rigidBody.setMass(mass);
        }
    }
Alter the mass of the named bone/torso.

@param boneName the name of the bone, or torsoName (not null)
@param mass the desired mass (&gt;0)
jme3-jbullet/src/main/java/com/jme3/bullet/animation/DacLinks.java