#102 FIX

src/main/java/io/appium/java_client/MissingParameterException.java

-/*
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * See the NOTICE file distributed with this work for additional
- * information regarding copyright ownership.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package io.appium.java_client;
-
-public class MissingParameterException
-    extends IllegalArgumentException {
-
-    private static final long serialVersionUID = 1L;
-
-    public MissingParameterException(String reason) {
-        super(reason);
-    }
-
-    public MissingParameterException(String reason, Throwable cause) {
-        super(reason, cause);
-    }
-}

src/main/java/io/appium/java_client/MultiTouchAction.java

@@ -16,10 +16,13 @@
 
 package io.appium.java_client;
 
+import static com.google.common.base.Preconditions.checkArgument;
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 
+import java.util.List;
+
 /**
  * Used for Webdriver 3 multi-touch gestures
  * See the Webriver 3 spec https://dvcs.w3.org/hg/webdriver/raw-file/default/webdriver-spec.html
@@ -62,16 +65,14 @@ public class MultiTouchAction implements PerformsActions<MultiTouchAction> {
      * Perform the multi-touch action on the mobile performsTouchActions.
      */
     public MultiTouchAction perform() {
-        int size = actions.build().size();
-        if (size > 1) {
+        List<TouchAction> touchActions = actions.build();
+        checkArgument(touchActions.size() > 0,
+                "MultiTouch action must have at least one TouchAction added before it can be performed");
+        if (touchActions.size() > 1) {
             performsTouchActions.performMultiTouchAction(this);
-        } else if (size == 1) {
+        } else {
             //android doesn't like having multi-touch actions with only a single TouchAction...
             performsTouchActions.performTouchAction(actions.build().get(0));
-        } else {
-            throw new MissingParameterException(
-                "MultiTouch action must have at least one TouchAction "
-                    + "added before it can be performed");
         }
         return this;
     }
@@ -80,9 +81,8 @@ public class MultiTouchAction implements PerformsActions<MultiTouchAction> {
         ImmutableList.Builder<Object> listOfActionChains = ImmutableList.builder();
         ImmutableList<TouchAction> touchActions = actions.build();
 
-        touchActions.forEach(action -> {
-            listOfActionChains.add(action.getParameters().get("actions"));
-        });
+        touchActions.forEach(action ->
+                listOfActionChains.add(action.getParameters().get("actions")));
         return ImmutableMap.of("actions", listOfActionChains.build());
     }