Added an InvalidMessageTypeException - thrown whenever we encounter a MessageType that isn't recognised or isn't supported.

Added EncoderFactory. This creates specific MessageEncoders. Supports JoinAcceptance and RequestToJoin.
Added MessageEncoder interface.
Added JoinAcceptanceEncoder.
Added encode(AC35Data) function to RaceVisionByteEncoder.
Added RequestToJonEncoder.
Updated RequestToJoin and JoinAcceptance decode/encode tests to use the above.

issue #35 #36
#story[1095]

racevisionGame/src/main/java/network/Exceptions/InvalidMessageTypeException.java

@@ -0,0 +1,17 @@
+package network.Exceptions;
+
+
+/**
+ * An exception thrown when we encounter a message type that isn't recognised.
+ */
+public class InvalidMessageTypeException extends Exception {
+
+
+    public InvalidMessageTypeException(String message) {
+        super(message);
+    }
+
+    public InvalidMessageTypeException(String message, Throwable cause) {
+        super(message, cause);
+    }
+}

racevisionGame/src/main/java/network/MessageEncoders/EncoderFactory.java

@@ -0,0 +1,44 @@
+package network.MessageEncoders;
+
+
+import network.Exceptions.InvalidMessageTypeException;
+import network.Messages.Enums.MessageType;
+
+/**
+ * Factory to create the appropriate encoder for a given message.
+ */
+public class EncoderFactory {
+
+
+    /**
+     * Private constructor. Currently doesn't need to be constructed.
+     */
+    private EncoderFactory(){
+
+    }
+
+
+    /**
+     * Creates the correct type of encoder for a given message type.
+     * @param type Type of message you want an encoder for.
+     * @return The encoder.
+     * @throws InvalidMessageTypeException If you pass in a {@link MessageType} that isn't recognised.
+     */
+    public static MessageEncoder create(MessageType type) throws InvalidMessageTypeException {
+
+
+        switch (type) {
+
+            case REQUEST_TO_JOIN: return new RequestToJoinEncoder();
+
+            case JOIN_ACCEPTANCE: return new JoinAcceptanceEncoder();
+
+
+            default: throw new InvalidMessageTypeException("Unrecognised message type: " + type);
+        }
+
+
+
+    }
+
+}

racevisionGame/src/main/java/network/MessageEncoders/JoinAcceptanceEncoder.java

@@ -0,0 +1,44 @@
+package network.MessageEncoders;
+
+
+import network.Messages.AC35Data;
+import network.Messages.JoinAcceptance;
+import network.Utils.ByteConverter;
+
+import java.nio.ByteBuffer;
+
+import static network.Utils.ByteConverter.intToBytes;
+
+/**
+ * This encoder can encode a {@link JoinAcceptance} message.
+ */
+public class JoinAcceptanceEncoder implements MessageEncoder {
+
+
+    /**
+     * Constructor.
+     */
+    public JoinAcceptanceEncoder() {
+    }
+
+
+    @Override
+    public byte[] encode(AC35Data message) {
+
+        //Downcast.
+        JoinAcceptance joinAcceptance = (JoinAcceptance) message;
+
+        //Message is 5 bytes.
+        ByteBuffer joinAcceptanceBuffer = ByteBuffer.allocate(5);
+
+        //Source ID is first four bytes.
+        joinAcceptanceBuffer.put(intToBytes(joinAcceptance.getSourceID(), 4));
+        //Acceptance type is next byte.
+        joinAcceptanceBuffer.put(intToBytes(joinAcceptance.getAcceptanceType().getValue(), 1));
+
+        byte [] result = joinAcceptanceBuffer.array();
+
+        return result;
+
+    }
+}

racevisionGame/src/main/java/network/MessageEncoders/MessageEncoder.java

@@ -0,0 +1,21 @@
+package network.MessageEncoders;
+
+
+import network.Messages.AC35Data;
+
+
+/**
+ * This is the interface that all message encoders must implement.
+ * It allows for {@link #encode(AC35Data)}ing messages.
+ */
+public interface MessageEncoder {
+
+
+    /**
+     * Encodes a given message.
+     * @param message The message to encode.
+     * @return Message in byte encoded form.
+     */
+    public byte[] encode(AC35Data message);
+
+}

racevisionGame/src/main/java/network/MessageEncoders/RaceVisionByteEncoder.java

@@ -1,6 +1,8 @@
 package network.MessageEncoders;
 
 
+import network.Exceptions.InvalidMessageException;
+import network.Exceptions.InvalidMessageTypeException;
 import network.Messages.*;
 
 import static network.Utils.ByteConverter.*;
@@ -348,40 +350,24 @@ public class RaceVisionByteEncoder {
 
 
     /**
-     * Encodes a {@link RequestToJoin} message.
-     * @param requestToJoin Message to encode.
+     * Encodes a given message.
+     * @param message Message to encode.
      * @return Encoded message.
+     * @throws InvalidMessageException If the message cannot be encoded.
      */
-    public static byte[] requestToJoin(RequestToJoin requestToJoin) {
+    public static byte[] encode(AC35Data message) throws InvalidMessageException {
 
-        ByteBuffer requestToJoinBuffer = ByteBuffer.allocate(4);
-
-        requestToJoinBuffer.put(intToBytes(requestToJoin.getRequestType().getValue(), 4));
-
-        byte [] result = requestToJoinBuffer.array();
+        MessageEncoder encoder = null;
+        try {
+            encoder = EncoderFactory.create(message.getType());
+        } catch (InvalidMessageTypeException e) {
+            throw new InvalidMessageException("Could not create encoder for MessageType: " + message.getType(), e);
+        }
 
-        return result;
+        byte[] encodedMessage = encoder.encode(message);
 
+        return encodedMessage;
     }
 
-    /**
-     * Encodes a {@link JoinAcceptance} message.
-     * @param joinAcceptance Message to encode.
-     * @return Encoded message.
-     */
-    public static byte[] joinAcceptance(JoinAcceptance joinAcceptance) {
 
-        //Message is 5 bytes.
-        ByteBuffer joinAcceptanceBuffer = ByteBuffer.allocate(5);
-
-        //Source ID is first four bytes.
-        joinAcceptanceBuffer.put(intToBytes(joinAcceptance.getSourceID(), 4));
-        //Acceptance type is next byte.
-        joinAcceptanceBuffer.put(intToBytes(joinAcceptance.getAcceptanceType().getValue(), 1));
-
-        byte [] result = joinAcceptanceBuffer.array();
-
-        return result;
-
-    }
 }

racevisionGame/src/main/java/network/MessageEncoders/RequestToJoinEncoder.java

@@ -0,0 +1,39 @@
+package network.MessageEncoders;
+
+
+import network.Messages.AC35Data;
+import network.Messages.RequestToJoin;
+import network.Utils.ByteConverter;
+
+import java.nio.ByteBuffer;
+
+/**
+ * This encoder can encode a {@link network.Messages.RequestToJoin} message.
+ */
+public class RequestToJoinEncoder implements MessageEncoder {
+
+
+    /**
+     * Constructor.
+     */
+    public RequestToJoinEncoder() {
+    }
+
+
+    @Override
+    public byte[] encode(AC35Data message) {
+
+        //Downcast.
+        RequestToJoin requestToJoin = (RequestToJoin) message;
+
+
+        ByteBuffer requestToJoinBuffer = ByteBuffer.allocate(4);
+
+        requestToJoinBuffer.put(ByteConverter.intToBytes(requestToJoin.getRequestType().getValue(), 4));
+
+        byte [] result = requestToJoinBuffer.array();
+
+        return result;
+
+    }
+}

racevisionGame/src/test/java/network/MessageDecoders/JoinAcceptanceDecoderTest.java

@@ -1,5 +1,6 @@
 package network.MessageDecoders;
 
+import network.Exceptions.InvalidMessageException;
 import network.MessageEncoders.RaceVisionByteEncoder;
 import network.Messages.Enums.JoinAcceptanceEnum;
 import network.Messages.JoinAcceptance;
@@ -19,10 +20,10 @@ public class JoinAcceptanceDecoderTest {
      * @param message Message to encode/decode.
      * @return The decoded message.
      */
-    private JoinAcceptance encodeDecodeMessage(JoinAcceptance message) {
+    private JoinAcceptance encodeDecodeMessage(JoinAcceptance message) throws InvalidMessageException {
 
         //Encode.
-        byte [] testEncodedMessage = RaceVisionByteEncoder.joinAcceptance(message);
+        byte [] testEncodedMessage = RaceVisionByteEncoder.encode(message);
 
         //Decode.
         JoinAcceptanceDecoder testDecoder = new JoinAcceptanceDecoder(testEncodedMessage);

racevisionGame/src/test/java/network/MessageDecoders/RequestToJoinDecoderTest.java

@@ -1,5 +1,6 @@
 package network.MessageDecoders;
 
+import network.Exceptions.InvalidMessageException;
 import network.MessageEncoders.RaceVisionByteEncoder;
 import network.Messages.Enums.RequestToJoinEnum;
 import network.Messages.RequestToJoin;
@@ -20,10 +21,10 @@ public class RequestToJoinDecoderTest {
      * @param message Message to encode/decode.
      * @return The decoded message.
      */
-    private RequestToJoin encodeDecodeMessage(RequestToJoin message) {
+    private RequestToJoin encodeDecodeMessage(RequestToJoin message) throws InvalidMessageException {
 
         //Encode.
-        byte [] testEncodedMessage = RaceVisionByteEncoder.requestToJoin(message);
+        byte [] testEncodedMessage = RaceVisionByteEncoder.encode(message);
 
         //Decode.
         RequestToJoinDecoder testDecoder = new RequestToJoinDecoder(testEncodedMessage);