hadoop wordcount Unsuppored Major.Minor版本51.0错误

Question

我在Hadoop 1.1.1中为wordcount创建了一个jar文件,同时运行world count,它给出了以下错误:

hduseros@MT2012018:/usr/local/hadoop$ bin/hadoop jar playground/wordcount.jar org.apache.hadoop.examples.WordCount /user/input/playground /user/output1
Exception in thread "main" java.lang.UnsupportedClassVersionError: org/apache/hadoop/examples/WordCount : Unsupported major.minor version 51.0
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:634)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:277)
    at java.net.URLClassLoader.access$000(URLClassLoader.java:73)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:212)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:264)
    at org.apache.hadoop.util.RunJar.main(RunJar.java:149)

Answer 1

当您的hadoop系统运行的Java版本低于用于编译MapReduce代码的Java版本时,会出现此错误.

检查用于编译代码的java版本的hadoop系统和系统" java -version ".