diff --git a/.travis.yml b/.travis.yml
index 591079b6a..5b0f7f1d9 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,7 +1,7 @@
 language: java
 matrix:
   include:
-    - jdk: oraclejdk8
+    - jdk: oraclejdk9
 
 script:
   - (cd test && ./runtests.sh) # I/O tests
@@ -18,4 +18,4 @@ deploy:
 addons:
   apt:
     packages:
-      - oracle-java8-installer
+      - oracle-java9-installer
diff --git a/docs/DeveloperGuide.adoc b/docs/DeveloperGuide.adoc
index a3bb62169..e1627b426 100644
--- a/docs/DeveloperGuide.adoc
+++ b/docs/DeveloperGuide.adoc
@@ -7,7 +7,7 @@
 
 *Prerequisites*
 
-* JDK 8 or later
+* JDK 9 or later
 * IntelliJ IDE
 
 *Importing the project into IntelliJ*
@@ -16,7 +16,7 @@
 . Open IntelliJ (if you are not in the welcome screen, click `File` > `Close Project` to close the existing project dialog first)
 . Set up the correct JDK version
 .. Click `Configure` > `Project Defaults` > `Project Structure`
-.. If JDK 8 is listed in the drop down, select it. If it is not, click `New...` and select the directory where you installed JDK 8.
+.. If JDK 9 is listed in the drop down, select it. If it is not, click `New...` and select the directory where you installed JDK 9.
 .. Click `OK`.
 . Click `Import Project`
 . Locate the project directory and click `OK`
diff --git a/test/java/seedu/addressbook/common/UtilsTest.java b/test/java/seedu/addressbook/common/UtilsTest.java
index 012a6715d..23ea62b45 100644
--- a/test/java/seedu/addressbook/common/UtilsTest.java
+++ b/test/java/seedu/addressbook/common/UtilsTest.java
@@ -30,8 +30,8 @@ public void elementsAreUnique() throws Exception {
         assertNotUnique("abc", "abc");
         assertNotUnique("abc", "", "abc", "ABC");
         assertNotUnique("", "abc", "a", "abc");
-        assertNotUnique(1, new Integer(1));
-        assertNotUnique(null, 1, new Integer(1));
+        assertNotUnique(1, Integer.valueOf(1));
+        assertNotUnique(null, 1, Integer.valueOf(1));
         assertNotUnique(null, null);
         assertNotUnique(null, "a", "b", null);
     }