# Package org.optaplanner.core.api.score.stream.quad

The `ConstraintStream` API for four matched facts.

- Interface Summary
  Interface | Description
  --- | ---
  QuadConstraintCollector<A,​B,​C,​D,​ResultContainer_,​Result_> | Usually created with `ConstraintCollectors`.
  QuadConstraintStream<A,​B,​C,​D> | A `ConstraintStream` that matches four facts.
  QuadJoiner<A,​B,​C,​D> | Created with `Joiners`.