Only allow one connection per in/out pair.

app/src/main/java/com/codigoparallevar/minicards/types/RoundOutputConnector.java

@@ -9,6 +9,7 @@ import com.codigoparallevar.minicards.types.connectors.output.OutputConnector;
 import com.codigoparallevar.minicards.types.connectors.output.SignalOutputConnector;
 import com.codigoparallevar.minicards.types.wireData.Signal;
 
+import java.util.HashSet;
 import java.util.LinkedList;
 import java.util.List;
 
@@ -20,6 +21,7 @@ public class RoundOutputConnector implements Drawable, SignalOutputConnector {
     private final Part _part;
     private SignalWire _currentWire = null;
     private final List<SignalWire> _wires;
+    private final HashSet<InputConnector> _connections;
 
     public RoundOutputConnector(Part part, PartGrid partGrid, int centerX, int centerY, int radius) {
         _part = part;
@@ -28,6 +30,7 @@ public class RoundOutputConnector implements Drawable, SignalOutputConnector {
         _centerY = centerY;
         _radius  = radius;
         _wires = new LinkedList<>();
+        _connections = new HashSet<>();
     }
 
     @Override
@@ -61,10 +64,17 @@ public class RoundOutputConnector implements Drawable, SignalOutputConnector {
 
             Log.d("RoundOutputConnector", "Dropped wire on " + resultPoint);
 
+            // Not connected
             if (resultPoint == null){
                 return;
             }
 
+            // Already connected
+            if (_connections.contains(resultPoint)) {
+                return;
+            }
+            _connections.add(resultPoint);
+
             wire.attachTo(resultPoint);
             _wires.add(wire);
         }
@@ -111,6 +121,12 @@ public class RoundOutputConnector implements Drawable, SignalOutputConnector {
 
     @Override
     public void connectTo(SignalInputConnector inputConnector) {
+        if (_connections.contains(inputConnector)) {
+            return;
+        }
+
+        _connections.add(inputConnector);
+
         SignalWire wire = new SignalWire(this, _centerX, _centerY);
         wire.attachTo(inputConnector);
         _wires.add(wire);

build.gradle

@@ -7,7 +7,7 @@ buildscript {
         jcenter()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:3.0.0-alpha5'
+        classpath 'com.android.tools.build:gradle:3.0.0-beta2'
         
 
         // NOTE: Do not place your application dependencies here; they belong