Integrate finish() and promptForSide().

vassal-app/src/main/java/VASSAL/build/module/PlayerRoster.java

@@ -469,23 +469,9 @@ public void finish() {
       GameModule.getGameModule().warn(Resources.getString("PlayerRoster.failed_pref_write", e.getLocalizedMessage()));
     }
 
-    String newSide = untranslateSide(sideConfig.getValueString());
-    final ArrayList<String> alreadyTaken = new ArrayList<>();
-
-    // Check if attempting switch to side taken whilst dialog was active. If found, return without setting side i.e. pickedSide = false.
-    for (final PlayerInfo p : players) {
-      alreadyTaken.add(p.side);
-    }
-
-    while (alreadyTaken.contains(newSide)) {
-      wc.setProblem(newSide + " already taken"); // Resources.getString("PlayerRoster.side_unavailable")
-      newSide = String.valueOf(getControls());
-      alreadyTaken.clear();
-      for (final PlayerInfo p : players) {
-        alreadyTaken.add(p.side);
-      }
-      newSide = untranslateSide(sideConfig.getValueString());
-    }
+   // Drop into standard routine, starting with checking side is still available (race condition mitigation)
+    // returns untranslated side
+    String newSide = promptForSide(sideConfig.getValueString());
 
     if (newSide != null) {
       if (GameModule.getGameModule().isMultiplayerConnected()) {
@@ -774,10 +760,20 @@ public List<String> getAvailableSides() {
     return availableSides;
   }
 
-  protected String promptForSide() {
+  protected String promptForSide(String newSide) {
+
     final ArrayList<String> availableSides = new ArrayList<>(sides);
     final ArrayList<String> alreadyTaken = new ArrayList<>();
-    String newSide = "";
+    boolean fromWizard;
+    boolean found = false;       // Set when we find a usable side
+
+    if (newSide == null) {
+      newSide = "";
+      fromWizard = false;
+    }
+    else {
+      fromWizard = true;
+    }
 
     while (newSide != null) { // Loops until a valid side is found or op is canceled (repeats side check to minimuse race condition window)
 
@@ -807,15 +803,16 @@ protected String promptForSide() {
       // Thus hotseat players can easily cycle through the player positions as they will appear successively as the default.
       // Common names for Solitaire players (Solitaire, Solo, Referee) do not count as "real" player sides, and will be skipped.
       // If we have no "next" side available to offer, we stay with the observer side as our default offering.
-      final String mySide = getMySide(); // Get our own side, so we can find the "next" one
-      final int myidx = (mySide != null) ? sides.indexOf(mySide) : -1; // See if we have a current non-observe side.
-      boolean found = false;       // Set when we find a usable side
-      int i = (myidx >= 0) ? ((myidx + 1) % sides.size()) : 0;   // If we do, start looking in the "next" slot, otherwise start at beginning.
-      for (int tries = 0; i != myidx && tries < sides.size(); i = (i + 1) % sides.size(), tries++) { // Wrap-around search of sides
-        final String s = sides.get(i);
-        if (!alreadyTaken.contains(s) && !isSoloSide(s)) {
-          found = true; // Found an available slot that's not our current one and not a "solo" slot.
-          break;
+      if (!fromWizard) {
+        final String mySide = getMySide(); // Get our own side, so we can find the "next" one
+        final int myidx = (mySide != null) ? sides.indexOf(mySide) : -1; // See if we have a current non-observe side.
+        int i = (myidx >= 0) ? ((myidx + 1) % sides.size()) : 0;   // If we do, start looking in the "next" slot, otherwise start at beginning.
+        for (int tries = 0; i != myidx && tries < sides.size(); i = (i + 1) % sides.size(), tries++) { // Wrap-around search of sides
+          final String s = sides.get(i);
+          if (!alreadyTaken.contains(s) && !isSoloSide(s)) {
+            found = true; // Found an available slot that's not our current one and not a "solo" slot.
+            break;
+          }
         }
       }