Task 2 - errors handler

src/main/java/CalculatorClient.java

@@ -2,24 +2,42 @@ import ch.sdi.calc.CalculatorGrpc;
 import ch.sdi.calc.CalculatorOuterClass;
 import io.grpc.ManagedChannel;
 import io.grpc.ManagedChannelBuilder;
+import io.grpc.StatusRuntimeException;
+
+import java.util.concurrent.TimeUnit;
+import java.util.logging.Level;
+import java.util.logging.Logger;
 
 public class CalculatorClient {
 
     private ManagedChannel channel;
-    private final CalculatorGrpc.CalculatorBlockingStub blockingStub;
+    private CalculatorGrpc.CalculatorBlockingStub blockingStub = null;
+    private static final Logger logger = Logger.getLogger(CalculatorClient.class.getName());
 
     public CalculatorClient(String host, int port) {
         this(ManagedChannelBuilder.forAddress(host, port).usePlaintext());
     }
     private CalculatorClient(ManagedChannelBuilder<?> channelBuilder) {
+        try {
             channel = channelBuilder.build();
+        } catch (Exception e) {
+            logger.log(Level.WARNING, "Could not connect to server: {0}", e.getMessage());
+            return;
+        }
         blockingStub = CalculatorGrpc.newBlockingStub(channel);
     }
 
     public double calculate(String expression) {
+        logger.info("Trying to do: " + expression + " ..." );
         CalculatorOuterClass.CalculatorRequest request = CalculatorOuterClass.CalculatorRequest.newBuilder().setExpression(expression).build();
-        CalculatorOuterClass.CalculatorResponse response;
+        CalculatorOuterClass.CalculatorResponse response = null;
+        try {
             response = blockingStub.calculate(request);
+        } catch (StatusRuntimeException e) {
+            logger.log(Level.WARNING, "RPC failed: {0}", e.getStatus());
+            return 0;
+        }
+        logger.info("Answer: " + response.getResult());
         return response.getResult();
     }
 
@@ -32,5 +50,10 @@ public class CalculatorClient {
             double answer = client.calculate(expression);
             System.out.println("Answer: " + answer);
         }
+
+        String expression = "1-a";
+        System.out.println("Expression: " + expression);
+        double answer = client.calculate(expression);
+        System.out.println("Answer: " + answer);
     }
 }