changes to placeholder identifier and (de)serialization

java/com.sap.sailing.domain.common/src/com/sap/sailing/domain/common/racelog/tracking/SingleTypeBasedServiceFinderImpl.java

@@ -1,21 +1,37 @@
 package com.sap.sailing.domain.common.racelog.tracking;
 
-
+/**
+ * Only can provide the service for a single {@code type}, e.g. on smartphones with no OSGi context.
+ * Optionally, a {@link #setFallbackService(Object) fallback} can be set.
+ * @author Fredrik Teschke
+ */
 public class SingleTypeBasedServiceFinderImpl<ServiceType> implements
 TypeBasedServiceFinder<ServiceType> {
     private final ServiceType service;
     private final String type;
+    private ServiceType fallback;
 
-    public SingleTypeBasedServiceFinderImpl(ServiceType service, String type) {
+    public SingleTypeBasedServiceFinderImpl(ServiceType service, ServiceType fallback, String type) {
         this.service = service;
         this.type = type;
+        this.fallback = fallback;
+    }
+
+    public SingleTypeBasedServiceFinderImpl(ServiceType service, String type) {
+        this(service, null, type);
     }
 
     @Override
     public ServiceType findService(String type)
             throws NoCorrespondingServiceRegisteredException {
         if (type.equals(this.type)) return service;
+        if (fallback != null) return fallback;
         throw new NoCorrespondingServiceRegisteredException("Only one service registered", type, service.getClass());
     }
 
+    @Override
+    public void setFallbackService(ServiceType fallback) {
+        this.fallback = fallback;
+    }
+
 }

java/com.sap.sailing.domain.common/src/com/sap/sailing/domain/common/racelog/tracking/TypeBasedServiceFinder.java

@@ -12,7 +12,18 @@ public interface TypeBasedServiceFinder<ServiceType> {
      * Find a service that implements the <ServiceType> interface for the specified {@code type}
      * of object (e.g. type of a {@link GPSFix}).
      * @param type A {@link String} that specifies for which type the service should be registered
-     * @throws NoCorrespondingServiceRegisteredException
+     * @throws NoCorrespondingServiceRegisteredException Thrown, if no service is registered for this type.
      */
     ServiceType findService(String type) throws NoCorrespondingServiceRegisteredException;
+    
+    /**
+     * Sets a fallback service (optional), that is used if no service is registered for a {@code type}.
+     * This should be a generic service, that can deal with any {@code type}, and provides a
+     * "better-than-nothing" implementation, which will be returned instead of throwing a
+     * {@link NoCorrespondingServiceRegisteredException}.
+     * <p>
+     * This method does not need to be implemented, but can remain a stub, if no fallback behaviour
+     * is desired.
+     */
+    void setFallbackService(ServiceType fallback);
 }