Installing ANT on AWS EC2: Unable to locate tools.jar

When I try and use ANT, I get this message:

Unable to locate tools.jar. Expected to find it in /usr/lib/jvm/java-1.6.0-openjdk-1.6.0.0/lib/tools.jar

Most forum posts say to just install Sun Java. Loads of other ones said to check your JAVA_HOME variable and to ensure you had installed the JDK, and not just the JRE. Ultimately, the solution to this problem for me was installing the devel version of the JDK:

sudo yum install java-1.6.0-openjdk-devel