Degrade Java 7 to Java 6 on an Amazon EC2 Linux

Amazon EC2 has updated its default java version with Java 7 in each EC2 server, but some featurs for solr 4.7 only work fine with Java 6. ex, it will cause the exception for solr 4.7 with Java 7:

java.lang.NoClassDefFoundError: org/apache/lucene/analysis/cn/smart/SentenceTokenizer

So we have to change the Java version, you only need to follow two steps:

1, We need to install java-1.6.0-openjdk firstly, the command is :

sudo yum install java-1.6.0-openjdk

2, Choose your default java version:

sudo alternatives --config java

And then you need to choose the number, then you can use the java -version to check the latest environment.

Of course, if you want to upgrade the new Java version, for example, from Java 7 to Java 8, you can do it in the same way.