Use orElseGet instead of orElse

orElse is a trap because it evaluates even if the Optional is empty.
orElseGet is the correct way.

src/main/java/world/bentobox/bentobox/api/commands/CompositeCommand.java

@@ -602,7 +602,7 @@ public abstract class CompositeCommand extends Command implements PluginIdentifi
             return options;
         }
         // Add any tab completion from the subcommand
-        options.addAll(command.tabComplete(User.getInstance(sender), alias, new LinkedList<>(Arrays.asList(args))).orElse(new ArrayList<>()));
+        options.addAll(command.tabComplete(User.getInstance(sender), alias, new LinkedList<>(Arrays.asList(args))).orElseGet(() -> new ArrayList<>()));
         if (command.hasSubCommands()) {
             options.addAll(getSubCommandLabels(sender, command));
         }

src/main/java/world/bentobox/bentobox/api/commands/admin/AdminRegisterCommand.java

@@ -61,7 +61,9 @@ public class AdminRegisterCommand extends ConfirmableCommand {
         }
         // Check if island is owned
         Optional<Island> island = getIslands().getIslandAt(user.getLocation());
-        if (island.map(Island::isOwned).orElse(false)) {
+        if (island.filter(Island::isOwned)
+                .filter(i -> !i.getOwner().equals(targetUUID))
+                .isPresent()) {
             user.sendMessage("commands.admin.register.already-owned");
             return false;
         }

src/main/java/world/bentobox/bentobox/api/commands/island/IslandSettingsCommand.java

@@ -39,7 +39,7 @@ public class IslandSettingsCommand extends CompositeCommand {
 
     @Override
     public boolean execute(User user, String label, List<String> args) {
-        Island island = getIslands().getIslandAt(user.getLocation()).orElse(getIslands().getIsland(user.getWorld(), user.getUniqueId()));
+        Island island = getIslands().getIslandAt(user.getLocation()).orElseGet(() -> getIslands().getIsland(user.getWorld(), user.getUniqueId()));
         new TabbedPanelBuilder()
         .user(user)
         .world(getWorld())

src/main/java/world/bentobox/bentobox/api/flags/FlagListener.java

@@ -146,7 +146,7 @@ public abstract class FlagListener implements Listener {
             } else {
                 report(user, e, loc, flag,  flag.isSetForWorld(loc.getWorld()) ? Why.SETTING_ALLOWED_IN_WORLD : Why.SETTING_NOT_ALLOWED_IN_WORLD);
             }
-            return island.map(x -> x.isAllowed(flag)).orElse(flag.isSetForWorld(loc.getWorld()));
+            return island.map(x -> x.isAllowed(flag)).orElseGet(() -> flag.isSetForWorld(loc.getWorld()));
         }
 
         // Protection flag

src/main/java/world/bentobox/bentobox/database/DatabaseSetup.java

@@ -43,7 +43,7 @@ public interface DatabaseSetup {
                 .filter(plugin.getSettings().getDatabaseType()::equals)
                 .findFirst()
                 .map(t -> t.database)
-                .orElse(DatabaseType.JSON.database);
+                .orElseGet(() -> DatabaseType.JSON.database);
     }
 
     /**

src/main/java/world/bentobox/bentobox/hooks/placeholders/PlaceholderAPIHook.java

@@ -113,7 +113,7 @@ public class PlaceholderAPIHook extends PlaceholderHook {
         // Transform [gamemode] in string to the game mode description name, or remove it for the default replacement
         String newString = BentoBox.getInstance().getIWM().getAddon(player.getWorld()).map(gm ->
         string.replace(TextVariables.GAMEMODE, gm.getDescription().getName().toLowerCase())
-        ).orElse(removeGMPlaceholder(string));
+                ).orElseGet(() -> removeGMPlaceholder(string));
         return PlaceholderAPI.setPlaceholders(player, newString);
     }
 

src/main/java/world/bentobox/bentobox/listeners/PortalTeleportationListener.java

@@ -150,7 +150,7 @@ public class PortalTeleportationListener implements Listener {
         // If entering an ender portal in the End.
         if (fromWorld.getEnvironment() == Environment.THE_END) {
             // If this is from the island nether, then go to the same vector, otherwise try island home location
-            Location to = plugin.getIslands().getIslandAt(e.getFrom()).map(i -> i.getSpawnPoint(Environment.NORMAL)).orElse(e.getFrom().toVector().toLocation(overWorld));
+            Location to = plugin.getIslands().getIslandAt(e.getFrom()).map(i -> i.getSpawnPoint(Environment.NORMAL)).orElseGet(() -> e.getFrom().toVector().toLocation(overWorld));
             e.setCancelled(true);
             // Else other worlds teleport to the overworld
             new SafeSpotTeleport.Builder(plugin)
@@ -165,7 +165,7 @@ public class PortalTeleportationListener implements Listener {
         World endWorld = plugin.getIWM().getEndWorld(overWorld);
         // If this is to island End, then go to the same vector, otherwise try spawn
         Optional<Island> optionalIsland = plugin.getIslands().getIslandAt(e.getFrom());
-        Location to = optionalIsland.map(i -> i.getSpawnPoint(Environment.THE_END)).orElse(e.getFrom().toVector().toLocation(endWorld));
+        Location to = optionalIsland.map(i -> i.getSpawnPoint(Environment.THE_END)).orElseGet(() -> e.getFrom().toVector().toLocation(endWorld));
         e.setCancelled(true);
         // Check if there is a missing end island
         if (plugin.getIWM().isPasteMissingIslands(overWorld)
@@ -247,7 +247,7 @@ public class PortalTeleportationListener implements Listener {
         // If entering a nether portal in the nether, teleport to portal in overworld if there is one
         if (fromWorld.getEnvironment() == Environment.NETHER) {
             // If this is from the island nether, then go to the same vector, otherwise try island home location
-            Location to = plugin.getIslands().getIslandAt(e.getFrom()).map(i -> i.getSpawnPoint(Environment.NORMAL)).orElse(e.getFrom().toVector().toLocation(overWorld));
+            Location to = plugin.getIslands().getIslandAt(e.getFrom()).map(i -> i.getSpawnPoint(Environment.NORMAL)).orElseGet(() -> e.getFrom().toVector().toLocation(overWorld));
             e.setCancelled(true);
             // Else other worlds teleport to the nether
             new SafeSpotTeleport.Builder(plugin)
@@ -262,7 +262,7 @@ public class PortalTeleportationListener implements Listener {
         World nether = plugin.getIWM().getNetherWorld(overWorld);
         // If this is to island nether, then go to the same vector, otherwise try spawn
         Optional<Island> optionalIsland = plugin.getIslands().getIslandAt(e.getFrom());
-        Location to = optionalIsland.map(i -> i.getSpawnPoint(Environment.NETHER)).orElse(e.getFrom().toVector().toLocation(nether));
+        Location to = optionalIsland.map(i -> i.getSpawnPoint(Environment.NETHER)).orElseGet(() -> e.getFrom().toVector().toLocation(nether));
         e.setCancelled(true);
         // Check if there is an island there or not
         if (plugin.getIWM().isPasteMissingIslands(overWorld) &&

src/main/java/world/bentobox/bentobox/listeners/flags/protection/FireListener.java

@@ -38,7 +38,7 @@ public class FireListener extends FlagListener {
             return false;
         }
         // Check if the island exists and if fire is allowed
-        boolean cancel = getIslands().getIslandAt(l).map(i -> !i.isAllowed(flag)).orElse(!flag.isSetForWorld(l.getWorld()));
+        boolean cancel = getIslands().getIslandAt(l).map(i -> !i.isAllowed(flag)).orElseGet(() -> !flag.isSetForWorld(l.getWorld()));
         e.setCancelled(cancel);
         return cancel;
     }

src/main/java/world/bentobox/bentobox/listeners/flags/protection/TNTListener.java

@@ -95,7 +95,7 @@ public class TNTListener extends FlagListener {
 
     protected boolean protect(Location location) {
         return getIslands().getProtectedIslandAt(location).map(i -> !i.isAllowed(Flags.TNT_DAMAGE))
-                .orElse(!Flags.WORLD_TNT_DAMAGE.isSetForWorld(location.getWorld()));
+                .orElseGet(() -> !Flags.WORLD_TNT_DAMAGE.isSetForWorld(location.getWorld()));
     }
 
     /**

src/main/java/world/bentobox/bentobox/listeners/flags/settings/DecayListener.java

@@ -29,6 +29,6 @@ public class DecayListener extends FlagListener {
 
         Optional<Island> island = getIslands().getIslandAt(e.getBlock().getLocation());
         // Cancel the event if needed - this means if this is not allowed on the island or in the world.
-        e.setCancelled(island.map(i -> !i.isAllowed(Flags.LEAF_DECAY)).orElse(!Flags.LEAF_DECAY.isSetForWorld(e.getBlock().getWorld())));
+        e.setCancelled(island.map(i -> !i.isAllowed(Flags.LEAF_DECAY)).orElseGet(() -> !Flags.LEAF_DECAY.isSetForWorld(e.getBlock().getWorld())));
     }
 }

src/main/java/world/bentobox/bentobox/listeners/flags/settings/MobSpawnListener.java

@@ -67,9 +67,9 @@ public class MobSpawnListener extends FlagListener {
     private boolean shouldCancel(Entity entity, Location loc, Flag animalSpawnFlag, Flag monsterSpawnFlag) {
         Optional<Island> island = getIslands().getIslandAt(loc);
         if (Util.isHostileEntity(entity) && !(entity instanceof PufferFish)) {
-            return island.map(i -> !i.isAllowed(monsterSpawnFlag)).orElse(!monsterSpawnFlag.isSetForWorld(entity.getWorld()));
+            return island.map(i -> !i.isAllowed(monsterSpawnFlag)).orElseGet(() -> !monsterSpawnFlag.isSetForWorld(entity.getWorld()));
         } else if (Util.isPassiveEntity(entity) || entity instanceof PufferFish) {
-            return island.map(i -> !i.isAllowed(animalSpawnFlag)).orElse(!animalSpawnFlag.isSetForWorld(entity.getWorld()));
+            return island.map(i -> !i.isAllowed(animalSpawnFlag)).orElseGet(() -> !animalSpawnFlag.isSetForWorld(entity.getWorld()));
         }
         return false;
     }

src/main/java/world/bentobox/bentobox/managers/IslandWorldManager.java

@@ -678,7 +678,7 @@ public class IslandWorldManager {
      * @return data folder file object or the plugin's data folder if none found
      */
     public File getDataFolder(@NonNull World world) {
-        return getAddon(world).map(GameModeAddon::getDataFolder).orElse(plugin.getDataFolder());
+        return getAddon(world).map(GameModeAddon::getDataFolder).orElseGet(() -> plugin.getDataFolder());
     }
 
     /**

src/main/java/world/bentobox/bentobox/managers/PlayersManager.java

@@ -296,7 +296,7 @@ public class PlayersManager {
         return playerCache.values().stream()
                 .filter(p -> p.getPlayerName().equalsIgnoreCase(name)).findFirst()
                 .map(p -> UUID.fromString(p.getUniqueId()))
-                .orElse(names.objectExists(name) ? names.loadObject(name).getUuid() : null);
+                .orElseGet(() -> names.objectExists(name) ? names.loadObject(name).getUuid() : null);
     }
 
     /**

src/main/java/world/bentobox/bentobox/util/teleport/SafeSpotTeleport.java

@@ -173,7 +173,7 @@ public class SafeSpotTeleport {
      */
     private List<Pair<Integer, Integer>> getChunksToScan() {
         List<Pair<Integer, Integer>> chunksToScan = new ArrayList<>();
-        int maxRadius = plugin.getIslands().getIslandAt(location).map(Island::getProtectionRange).orElse(plugin.getIWM().getIslandProtectionRange(location.getWorld()));
+        int maxRadius = plugin.getIslands().getIslandAt(location).map(Island::getProtectionRange).orElseGet(() -> plugin.getIWM().getIslandProtectionRange(location.getWorld()));
         maxRadius = Math.min(MAX_RADIUS, maxRadius);
         int x = location.getBlockX();
         int z = location.getBlockZ();

src/test/java/world/bentobox/bentobox/listeners/PortalTeleportationListenerTest.java

@@ -439,10 +439,10 @@ public class PortalTeleportationListenerTest {
         assertTrue(np.onNetherPortal(e));
         // Verify
         assertTrue(e.isCancelled());
-        // If nether islands, then to = from but in nether
+        // If nether islands, then to spawn location
-        verify(from).toVector();
+        verify(island).getSpawnPoint(eq(Environment.NETHER));
-        // Do not go to spawn
+        // Do not go to from
-        verify(nether, never()).getSpawnLocation();
+        verify(from, never()).toVector();
     }
 
     /**