Add getPotentialWorlds method to WorldManager.

src/main/java/com/onarandombox/MultiverseCore/api/MVWorldManager.java

@@ -335,4 +335,11 @@ public interface MVWorldManager {
      * does not exist. {@code includeLoaded} if the world exists and is loaded.
      */
     boolean hasUnloadedWorld(String name, boolean includeLoaded);
+
+    /**
+     * Get all the possible worlds that Multiverse has detected to be importable.
+     *
+     * @return A collection of world names that are deemed importable.
+     */
+    Collection<String> getPotentialWorlds();
 }

src/main/java/com/onarandombox/MultiverseCore/commands/ImportCommand.java

@@ -9,7 +9,6 @@ package com.onarandombox.MultiverseCore.commands;
 
 import com.onarandombox.MultiverseCore.MultiverseCore;
 import com.onarandombox.MultiverseCore.api.MVWorldManager;
-import com.onarandombox.MultiverseCore.api.MultiverseWorld;
 import com.onarandombox.MultiverseCore.utils.WorldNameChecker;
 import com.pneumaticraft.commandhandler.CommandHandler;
 import org.bukkit.ChatColor;
@@ -19,8 +18,6 @@ import org.bukkit.command.CommandSender;
 import org.bukkit.permissions.PermissionDefault;
 
 import java.io.File;
-import java.io.FilenameFilter;
-import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 
@@ -46,33 +43,17 @@ public class ImportCommand extends MultiverseCommand {
         this.worldManager = this.plugin.getMVWorldManager();
     }
 
-    private String getPotentialWorlds() {
+    private String getPotentialWorldStrings() {
-        File worldFolder = this.plugin.getServer().getWorldContainer();
+        final Collection<String> potentialWorlds = this.worldManager.getPotentialWorlds();
-        if (worldFolder == null) {
+        StringBuilder worldList = new StringBuilder();
-            return "";
-        }
-        File[] files = worldFolder.listFiles();
-        String worldList = "";
-        Collection<MultiverseWorld> worlds = this.worldManager.getMVWorlds();
-        List<String> worldStrings = new ArrayList<String>();
-        for (MultiverseWorld world : worlds) {
-            worldStrings.add(world.getName());
-        }
-        for (String world : this.worldManager.getUnloadedWorlds()) {
-            worldStrings.add(world);
-        }
         ChatColor currColor = ChatColor.WHITE;
-        for (File file : files) {
+
-            if (file.isDirectory() && WorldNameChecker.isValidWorldFolder(file) && !worldStrings.contains(file.getName())) {
+        for (String world : potentialWorlds) {
-                worldList += currColor + file.getName() + " ";
+            worldList.append(currColor).append(world).append(' ');
-                if (currColor == ChatColor.WHITE) {
+            currColor = currColor == ChatColor.WHITE ? ChatColor.YELLOW : ChatColor.WHITE;
-                    currColor = ChatColor.YELLOW;
-                } else {
-                    currColor = ChatColor.WHITE;
-                }
-            }
         }
-        return worldList;
+
+        return worldList.toString();
     }
     
     private String trimWorldName(String userInput) {
@@ -85,7 +66,7 @@ public class ImportCommand extends MultiverseCommand {
         String worldName = trimWorldName(args.get(0));
 
         if (worldName.toLowerCase().equals("--list") || worldName.toLowerCase().equals("-l")) {
-            String worldList = this.getPotentialWorlds();
+            String worldList = this.getPotentialWorldStrings();
             if (worldList.length() > 2) {
                 sender.sendMessage(ChatColor.AQUA + "====[ These look like worlds ]====");
                 sender.sendMessage(worldList);
@@ -128,7 +109,7 @@ public class ImportCommand extends MultiverseCommand {
 
         if (!worldFile.exists()) {
             sender.sendMessage(ChatColor.RED + "FAILED.");
-            String worldList = this.getPotentialWorlds();
+            String worldList = this.getPotentialWorldStrings();
             sender.sendMessage("That world folder does not exist. These look like worlds to me:");
             sender.sendMessage(worldList);
         } else if (!WorldNameChecker.isValidWorldFolder(worldFile)) {

src/main/java/com/onarandombox/MultiverseCore/utils/WorldManager.java

@@ -36,19 +36,19 @@ import java.io.File;
 import java.io.FilenameFilter;
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Random;
 import java.util.Set;
 import java.util.Stack;
-import java.util.Arrays;
 import java.util.concurrent.Callable;
 import java.util.concurrent.ConcurrentHashMap;
-import java.util.logging.Level;
-import java.util.regex.Matcher;
 import java.util.regex.Pattern;
+import java.util.stream.Collectors;
 
 /**
  * Public facing API to add/remove Multiverse worlds.
@@ -956,4 +956,21 @@ public class WorldManager implements MVWorldManager {
 		}
 		return false;
 	}
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+	public Collection<String> getPotentialWorlds() {
+        File worldContainer = this.plugin.getServer().getWorldContainer();
+        if (worldContainer == null) {
+            return Collections.emptyList();
+        }
+        return Arrays.stream(worldContainer.listFiles())
+                .filter(File::isDirectory)
+                .filter(folder -> !this.isMVWorld(folder.getName(), false))
+                .filter(WorldNameChecker::isValidWorldFolder)
+                .map(File::getName)
+                .collect(Collectors.toList());
+    }
 }