Heuristics without settings are equal to any other of their class

NullActionHeuristic had no equals, so MCTS parameters read back from JSON did
not equal those written (TunableParametersTest). The same for the other
heuristics that hold no settings.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

Author: hopshackle

src/main/java/games/poker/metrics/PokerHandHeuristic.java

@@ -37,4 +37,16 @@ public double evaluateState(AbstractGameState gs, int playerId) {
 
         return (11 - hand.a.rank) / 10.0;
     }
+
+    // no settings (any fields are fixed, or worked out from the game): any two are the same heuristic, so that one
+    // read back from JSON equals the one written
+    @Override
+    public boolean equals(Object obj) {
+        return obj != null && obj.getClass() == getClass();
+    }
+
+    @Override
+    public int hashCode() {
+        return getClass().getName().hashCode();
+    }
 }

src/main/java/games/powergrid/PowerGridHeuristic.java

@@ -169,4 +169,15 @@ private static double clamp01(double v) {
         return v < 0 ? 0 : (v > 1 ? 1 : v);
     }
 
-}
+    // no settings (any fields are fixed, or worked out from the game): any two are the same heuristic, so that one
+    // read back from JSON equals the one written
+    @Override
+    public boolean equals(Object obj) {
+        return obj != null && obj.getClass() == getClass();
+    }
+
+    @Override
+    public int hashCode() {
+        return getClass().getName().hashCode();
+    }
+}

src/main/java/games/puertorico/PuertoRicoStateHeuristic.java

@@ -22,4 +22,16 @@ public double evaluateState(AbstractGameState gs, int playerId) {
         }
 
     }
+
+    // no settings (any fields are fixed, or worked out from the game): any two are the same heuristic, so that one
+    // read back from JSON equals the one written
+    @Override
+    public boolean equals(Object obj) {
+        return obj != null && obj.getClass() == getClass();
+    }
+
+    @Override
+    public int hashCode() {
+        return getClass().getName().hashCode();
+    }
 }

src/main/java/games/seasaltpaper/heuristics/LeadHeuristic.java

@@ -35,4 +35,16 @@ public double evaluateState(AbstractGameState gs, int playerId) {
         // only return 1 if won
         return Utils.clamp((scores[playerId] - max) / params.victoryCondition[gs.getNPlayers() - 2], -1, 1);
     }
+
+    // no settings (any fields are fixed, or worked out from the game): any two are the same heuristic, so that one
+    // read back from JSON equals the one written
+    @Override
+    public boolean equals(Object obj) {
+        return obj != null && obj.getClass() == getClass();
+    }
+
+    @Override
+    public int hashCode() {
+        return getClass().getName().hashCode();
+    }
 }

src/main/java/games/seasaltpaper/heuristics/ScoreAndHandHeuristic.java

@@ -25,4 +25,16 @@ public double evaluateState(AbstractGameState gs, int playerId) {
         // only return 1 if won
         return Utils.clamp(scoreAndHand/params.victoryCondition[gs.getNPlayers()-2], -1, 0.99);
     }
+
+    // no settings (any fields are fixed, or worked out from the game): any two are the same heuristic, so that one
+    // read back from JSON equals the one written
+    @Override
+    public boolean equals(Object obj) {
+        return obj != null && obj.getClass() == getClass();
+    }
+
+    @Override
+    public int hashCode() {
+        return getClass().getName().hashCode();
+    }
 }

src/main/java/games/seasaltpaper/heuristics/ScoreHeuristic.java

@@ -20,4 +20,16 @@ public double evaluateState(AbstractGameState gs, int playerId) {
         // only return 1 if won
         return Utils.clamp(gs.getGameScore(playerId)/params.victoryCondition[gs.getNPlayers()-2], -1, 0.99);
     }
+
+    // no settings (any fields are fixed, or worked out from the game): any two are the same heuristic, so that one
+    // read back from JSON equals the one written
+    @Override
+    public boolean equals(Object obj) {
+        return obj != null && obj.getClass() == getClass();
+    }
+
+    @Override
+    public int hashCode() {
+        return getClass().getName().hashCode();
+    }
 }

src/main/java/games/spades/SpadesHeuristic.java

@@ -145,4 +145,16 @@ public int suggestBid(SpadesGameState state, int playerId) {
 
         return Math.min(6, Math.max(1, suggestedBid));
     }
-} 
+
+    // no settings (any fields are fixed, or worked out from the game): any two are the same heuristic, so that one
+    // read back from JSON equals the one written
+    @Override
+    public boolean equals(Object obj) {
+        return obj != null && obj.getClass() == getClass();
+    }
+
+    @Override
+    public int hashCode() {
+        return getClass().getName().hashCode();
+    }
+}

src/main/java/games/stratego/StrategoHeuristic.java

@@ -54,5 +54,15 @@ public double evaluateState(AbstractGameState gs, int playerId) {
         return playerScore - oppScore;
     }
 
+    // no settings (any fields are fixed, or worked out from the game): any two are the same heuristic, so that one
+    // read back from JSON equals the one written
+    @Override
+    public boolean equals(Object obj) {
+        return obj != null && obj.getClass() == getClass();
+    }
 
+    @Override
+    public int hashCode() {
+        return getClass().getName().hashCode();
+    }
 }

src/main/java/games/virus/VirusHeuristic.java

@@ -24,4 +24,16 @@ public double evaluateState(AbstractGameState gs, int playerId) {
         }
         return nHealthyOrgans * 1.0 / vgs.playerBodies.get(playerId).organs.size();
     }
-}
+
+    // no settings (any fields are fixed, or worked out from the game): any two are the same heuristic, so that one
+    // read back from JSON equals the one written
+    @Override
+    public boolean equals(Object obj) {
+        return obj != null && obj.getClass() == getClass();
+    }
+
+    @Override
+    public int hashCode() {
+        return getClass().getName().hashCode();
+    }
+}

src/main/java/players/heuristics/MultiLeaderHeuristic.java

@@ -18,4 +18,16 @@ public double evaluateState(AbstractGameState gs, int playerId) {
 
         return retValue;
     }
-}
+
+    // no settings (any fields are fixed, or worked out from the game): any two are the same heuristic, so that one
+    // read back from JSON equals the one written
+    @Override
+    public boolean equals(Object obj) {
+        return obj != null && obj.getClass() == getClass();
+    }
+
+    @Override
+    public int hashCode() {
+        return getClass().getName().hashCode();
+    }
+}