From 3050d7f23e235702bf658ca5565517be1415a9d2 Mon Sep 17 00:00:00 2001
From: Conor <conor10@gmail.com>
Date: Wed, 31 May 2017 09:47:28 +1000
Subject: [PATCH] Fixed issue https://github.com/web3j/web3j/issues/98.

---
 README.rst                                   |  4 ++--
 build.gradle                                 |  2 +-
 docs/source/getting_started.rst              |  4 ++--
 src/main/java/org/web3j/tx/Contract.java     |  6 +++++-
 src/test/java/org/web3j/tx/ContractTest.java | 22 ++++++++++++++++++++
 5 files changed, 32 insertions(+), 6 deletions(-)

diff --git a/README.rst b/README.rst
index 7cc7e8923..45ead7dbf 100644
--- a/README.rst
+++ b/README.rst
@@ -85,7 +85,7 @@ Java 8:
    <dependency>
      <groupId>org.web3j</groupId>
      <artifactId>core</artifactId>
-     <version>2.2.1</version>
+     <version>2.2.2</version>
    </dependency>
 
 Android:
@@ -105,7 +105,7 @@ Java 8:
 
 .. code-block:: groovy
 
-   compile ('org.web3j:core:2.2.1')
+   compile ('org.web3j:core:2.2.2')
 
 Android:
 
diff --git a/build.gradle b/build.gradle
index 369f653b2..e7844c2d8 100644
--- a/build.gradle
+++ b/build.gradle
@@ -29,7 +29,7 @@ apply plugin: 'application'
 apply plugin: 'checkstyle'
 
 group 'org.web3j'
-version '2.2.1'
+version '2.2.2'
 
 sourceCompatibility = 1.8
 
diff --git a/docs/source/getting_started.rst b/docs/source/getting_started.rst
index c62bd8400..2ee91a4e4 100644
--- a/docs/source/getting_started.rst
+++ b/docs/source/getting_started.rst
@@ -13,7 +13,7 @@ Java 8:
    <dependency>
      <groupId>org.web3j</groupId>
      <artifactId>core</artifactId>
-     <version>2.2.1</version>
+     <version>2.2.2</version>
    </dependency>
 
 Android:
@@ -33,7 +33,7 @@ Java 8:
 
 .. code-block:: groovy
 
-   compile ('org.web3j:core:2.2.1')
+   compile ('org.web3j:core:2.2.2')
 
 Android:
 
diff --git a/src/main/java/org/web3j/tx/Contract.java b/src/main/java/org/web3j/tx/Contract.java
index 6254c8166..26432ea55 100644
--- a/src/main/java/org/web3j/tx/Contract.java
+++ b/src/main/java/org/web3j/tx/Contract.java
@@ -170,7 +170,11 @@ protected CompletableFuture<List<Type>> executeCallMultipleValueReturnAsync(
     protected <T extends Type> T executeCallSingleValueReturn(
             Function function) throws InterruptedException, ExecutionException {
         List<Type> values = executeCall(function);
-        return (T) values.get(0);
+        if (!values.isEmpty()) {
+            return (T) values.get(0);
+        } else {
+            return null;
+        }
     }
 
     protected List<Type> executeCallMultipleValueReturn(
diff --git a/src/test/java/org/web3j/tx/ContractTest.java b/src/test/java/org/web3j/tx/ContractTest.java
index a177750db..938ee9ac9 100644
--- a/src/test/java/org/web3j/tx/ContractTest.java
+++ b/src/test/java/org/web3j/tx/ContractTest.java
@@ -40,6 +40,7 @@
 import static org.hamcrest.CoreMatchers.equalTo;
 import static org.hamcrest.CoreMatchers.is;
 import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertThat;
 import static org.junit.Assert.assertTrue;
 import static org.mockito.Matchers.any;
@@ -147,6 +148,17 @@ public void testCallSingleValue() throws Exception {
         assertThat(contract.callSingleValue().get(), equalTo(new Utf8String("")));
     }
 
+    @Test
+    public void testCallSingleValueEmpty() throws Exception {
+        // Example taken from FunctionReturnDecoderTest
+
+        EthCall ethCall = new EthCall();
+        ethCall.setResult("0x");
+        prepareCall(ethCall);
+
+        assertNull(contract.callSingleValue().get());
+    }
+
     @Test
     public void testCallMultipleValue() throws Exception {
         EthCall ethCall = new EthCall();
@@ -160,6 +172,16 @@ public void testCallMultipleValue() throws Exception {
                         new Uint256(BigInteger.valueOf(7)))));
     }
 
+    @Test
+    public void testCallMultipleValueEmpty() throws Exception {
+        EthCall ethCall = new EthCall();
+        ethCall.setResult("0x");
+        prepareCall(ethCall);
+
+        assertThat(contract.callMultipleValue().get(),
+                equalTo(Collections.emptyList()));
+    }
+
     private void prepareCall(EthCall ethCall) {
         Request request = mock(Request.class);
         when(request.sendAsync()).thenReturn(Async.run(() -> ethCall));