(a) In any judicial district, other than the City of Philadelphia, where a community court has not been established or where one has been discontinued there shall be one justice of the peace in each magisterial district. The jurisdiction of the justice of the peace shall be as provided by law.

  (b) The General Assembly shall by law establish classes of magisterial districts solely on the basis of population and population density and shall fix the salaries to be paid justices of the peace in each class. The number and boundaries of magisterial districts of each class within each judicial district shall be established by the Supreme Court or by the courts of common pleas under the direction of the Supreme Court as required for the efficient administration of justice within each magisterial district.