src/de/steamwar/misslewars/MWTeam.java

@@ -80,7 +80,7 @@ public class MWTeam {
 		return spawn;
 	}
 
-	public void join (Player p) {
+	public void join(Player p) {
 		players.add(p);
 		p.teleport(spawn);
 		p.setGameMode(GameMode.SURVIVAL);
@@ -91,9 +91,8 @@ public class MWTeam {
 			MissileWars.startRound();
 	}
 	
-	public void leave (Player p) {
+	public void leave(Player p) {
-		if(!players.contains(p))
+		if (!players.contains(p)) return;
-			return;
 
 		players.remove(p);
 		sbteam.removePlayer(p);

src/de/steamwar/misslewars/data/TapeSet.java

@@ -0,0 +1,89 @@
+package de.steamwar.misslewars.data;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class TapeSet<T> {
+
+    private Map<T, Node<T>> nodeMap = new HashMap<>();
+    private Node<T> last = null;
+    private Node<T> currentIterator = null;
+
+    private class Node<T> {
+
+        private Node<T> next = null;
+        private Node<T> prev = null;
+        private T value;
+
+        public Node(T value) {
+            this.value = value;
+        }
+
+        private void unlink() {
+            if (!itself()) {
+                next.prev = prev;
+                prev.next = next;
+            }
+            next = null;
+            prev = null;
+        }
+
+        private void link(Node<T> prev) {
+            this.prev = prev;
+            next = prev.next;
+            next.prev = this;
+            prev.next = this;
+        }
+
+        private boolean itself() {
+            return next == prev && next == this;
+        }
+
+    }
+
+    public int size() {
+        return nodeMap.size();
+    }
+
+    public boolean isEmpty() {
+        return nodeMap.isEmpty();
+    }
+
+    public boolean contains(T t) {
+        return nodeMap.containsKey(t);
+    }
+
+    public void add(T t) {
+        if (nodeMap.containsKey(t)) return;
+        Node<T> node = new Node<>(t);
+        nodeMap.put(t, node);
+        if (last == null) {
+            last = node;
+            currentIterator = node;
+        } else {
+            node.link(last);
+        }
+    }
+
+    public void remove(T t) {
+        if (!nodeMap.containsKey(t)) return;
+        Node<T> node = nodeMap.get(t);
+        if (node.itself()) {
+            last = null;
+            currentIterator = null;
+        }
+        if (node == currentIterator) {
+            currentIterator = node.next;
+        }
+        node.unlink();
+        nodeMap.remove(t);
+    }
+
+    public T next() {
+        if (currentIterator == null) return null;
+        T value = currentIterator.value;
+        currentIterator = currentIterator.next;
+        return value;
+    }
+
+}