Convert getOrDefault() calls that create collections to computeIfAbsent(). (#10431)

Convert getOrDefault() calls that create collections to computeIfAbsent(). These are cheaper since the empty collections are not constructed if present and can avoid an extra put() call afterward, since computeIfAbsent() will add the new value, unlike getOrDefault().

Author: asvitkine

game-app/game-core/src/main/java/games/strategy/triplea/TripleAPlayer.java

@@ -780,15 +780,12 @@ public Map<Territory, Map<Unit, IntegerMap<Resource>>> selectKamikazeSuicideAtta
       for (final Entry<Territory, IntegerMap<Unit>> selectionEntry : selection.entrySet()) {
         final Territory territory = selectionEntry.getKey();
         final Map<Unit, IntegerMap<Resource>> currentTerr =
-            kamikazeSuicideAttacks.getOrDefault(territory, new HashMap<>());
+            kamikazeSuicideAttacks.computeIfAbsent(territory, key -> new HashMap<>());
         for (final Entry<Unit, Integer> unitEntry : selectionEntry.getValue().entrySet()) {
           final Unit unit = unitEntry.getKey();
-          final IntegerMap<Resource> currentUnit =
-              currentTerr.getOrDefault(unit, new IntegerMap<>());
-          currentUnit.add(resource, unitEntry.getValue());
-          currentTerr.put(unit, currentUnit);
+          final Integer amount = unitEntry.getValue();
+          currentTerr.computeIfAbsent(unit, key -> new IntegerMap<>()).add(resource, amount);
         }
-        kamikazeSuicideAttacks.put(territory, currentTerr);
       }
     }
     return kamikazeSuicideAttacks;

game-app/game-core/src/main/java/games/strategy/triplea/ai/AbstractBuiltInAi.java

@@ -309,10 +309,7 @@ public Map<Territory, Map<Unit, IntegerMap<Resource>>> selectKamikazeSuicideAtta
                 (UnitAttachment.get(u.getType()).getHitPoints()
                     * (Math.random() < .3 ? 1 : (Math.random() < .5 ? 2 : 3))));
         resourceMap.put(resource, num);
-        final Map<Unit, IntegerMap<Resource>> attMap =
-            kamikazeSuicideAttacks.getOrDefault(t, new HashMap<>());
-        attMap.put(u, resourceMap);
-        kamikazeSuicideAttacks.put(t, attMap);
+        kamikazeSuicideAttacks.computeIfAbsent(t, key -> new HashMap<>()).put(u, resourceMap);
         attackTokens.add(resource, -num);
         if (attackTokens.getInt(resource) <= 0) {
           attackTokens.removeKey(resource);

game-app/game-core/src/main/java/games/strategy/triplea/attachments/TechAbilityAttachment.java

@@ -480,7 +480,7 @@ private void setUnitAbilitiesGained(final String value) throws GameParseExceptio
     final String unitType = s[0];
     // validate that this unit exists in the xml
     final UnitType ut = getUnitType(unitType);
-    final Set<String> abilities = unitAbilitiesGained.getOrDefault(ut, new HashSet<>());
+    final Set<String> abilities = unitAbilitiesGained.computeIfAbsent(ut, key -> new HashSet<>());
     // start at 1
     for (int i = 1; i < s.length; i++) {
       final String ability = s[i];
@@ -494,7 +494,6 @@ private void setUnitAbilitiesGained(final String value) throws GameParseExceptio
       }
       abilities.add(ability);
     }
-    unitAbilitiesGained.put(ut, abilities);
   }
 
   private void setUnitAbilitiesGained(final Map<UnitType, Set<String>> value) {
@@ -678,10 +677,9 @@ public static Map<String, Set<UnitType>> getAirborneTargettedByAa(
         final Map<String, Set<UnitType>> mapAa = taa.getAirborneTargettedByAa();
         if (mapAa != null && !mapAa.isEmpty()) {
           for (final Entry<String, Set<UnitType>> entry : mapAa.entrySet()) {
-            final Set<UnitType> current =
-                airborneTargettedByAa.getOrDefault(entry.getKey(), new HashSet<>());
-            current.addAll(entry.getValue());
-            airborneTargettedByAa.put(entry.getKey(), current);
+            airborneTargettedByAa
+                .computeIfAbsent(entry.getKey(), key -> new HashSet<>())
+                .addAll(entry.getValue());
           }
         }
       }

game-app/game-core/src/main/java/games/strategy/triplea/delegate/battle/BattleDelegate.java

@@ -1298,10 +1298,7 @@ private void doKamikazeSuicideAttacks() {
             continue;
           }
         }
-        final Collection<Territory> currentTerrs =
-            kamikazeZonesByEnemy.getOrDefault(owner, new ArrayList<>());
-        currentTerrs.add(t);
-        kamikazeZonesByEnemy.put(owner, currentTerrs);
+        kamikazeZonesByEnemy.computeIfAbsent(owner, key -> new ArrayList<>()).add(t);
       }
     }
     if (kamikazeZonesByEnemy.isEmpty()) {

game-app/game-core/src/main/java/games/strategy/triplea/delegate/battle/ScrambleLogic.java

@@ -152,15 +152,11 @@ public Collection<Unit> getUnitsThatCanScramble() {
             ((DependentBattle) battle).getAmphibiousAttackTerritories();
         amphibFromTerrs.removeAll(territoriesWithBattlesWater);
         for (final Territory amphibFrom : amphibFromTerrs) {
-          final Set<Territory> canScrambleFrom =
-              scrambleTerrs.getOrDefault(amphibFrom, new HashSet<>());
           if (toAnyAmphibious) {
-            canScrambleFrom.addAll(getCanScrambleFromTerritories(amphibFrom));
+            final Collection<Territory> territories = getCanScrambleFromTerritories(amphibFrom);
+            scrambleTerrs.computeIfAbsent(amphibFrom, key -> new HashSet<>()).addAll(territories);
           } else if (canScrambleFromPredicate.test(battleTerr)) {
-            canScrambleFrom.add(battleTerr);
-          }
-          if (!canScrambleFrom.isEmpty()) {
-            scrambleTerrs.put(amphibFrom, canScrambleFrom);
+            scrambleTerrs.computeIfAbsent(amphibFrom, key -> new HashSet<>()).add(battleTerr);
           }
         }
       }