I was trying to use the joint_state class of gazebo API, but when i try to declare it as physics::JointStatePtr jointstatep; It shows:

 error: ‘JointStatePtr’ in namespace ‘gazebo::physics’ does not name a type
     private: physics::JointStatePtr js;
 error: ‘class gazebo::VelodynePlugin’ has no member named ‘JointPointer()’
       std::cout<<"position="<<this->JointPointer()->GetAngles()<<std::endl;

How do i use the JointPointer state class, to read the joint states of any joint. I tried this one but doesn't works:

public: void SetVelocity(const double &_vel)
{ 
  std::cerr=this->model->js;
  // Set the joint's target velocity
  this->model->GetJointController()->SetJointPosition(
      this->joint->GetScopedName(), _vel,0);
}

private: physics::JointState_M js;