java.lang.NoClassDefFoundError；java.io.IOException: Cannot initialize Cluster.

hadoop --wordcount在eclipse下运行出现的两个错误总结：

今天遇到的问题：

1：

Exception in thread "main" java.io.IOException: Cannot initialize Cluster. Please check your configuration for mapreduce.framework.name and the correspond server addresses.

解决方法：把 mapreduce,common and hdfs中的所有jar包都导入到工程中即可

2：问题二

java.lang.NoClassDefFoundError

<span style="font-size:18px;">Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/hadoop/yarn/util/Apps

at java.lang.ClassLoader.defineClass1(Native Method)

at java.lang.ClassLoader.defineClass(ClassLoader.java:800)

at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)

at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)

at java.net.URLClassLoader.access$100(URLClassLoader.java:71)

at java.net.URLClassLoader$1.run(URLClassLoader.java:361)

at java.net.URLClassLoader$1.run(URLClassLoader.java:355)

at java.security.AccessController.doPrivileged(Native Method)

at java.net.URLClassLoader.findClass(URLClassLoader.java:354)

at java.lang.ClassLoader.loadClass(ClassLoader.java:425)

at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)

at java.lang.ClassLoader.loadClass(ClassLoader.java:358)

at org.apache.hadoop.mapred.LocalDistributedCacheManager.setup(LocalDistributedCacheManager.java:93)

at org.apache.hadoop.mapred.LocalJobRunner$Job.<init>(LocalJobRunner.java:163)

at org.apache.hadoop.mapred.LocalJobRunner.submitJob(LocalJobRunner.java:731)

at org.apache.hadoop.mapreduce.JobSubmitter.submitJobInternal(JobSubmitter.java:536)

at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1296)

at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1293)

at java.security.AccessController.doPrivileged(Native Method)

at javax.security.auth.Subject.doAs(Subject.java:415)

at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1628)

at org.apache.hadoop.mapreduce.Job.submit(Job.java:1293)

at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:1314)

at WordCount.main(WordCount.java:70)

Caused by: java.lang.ClassNotFoundException: org.apache.hadoop.yarn.util.Apps

at java.net.URLClassLoader$1.run(URLClassLoader.java:366)

at java.net.URLClassLoader$1.run(URLClassLoader.java:355)

at java.security.AccessController.doPrivileged(Native Method)

at java.net.URLClassLoader.findClass(URLClassLoader.java:354)

at java.lang.ClassLoader.loadClass(ClassLoader.java:425)

at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)

at java.lang.ClassLoader.loadClass(ClassLoader.java:358)

... 24 more
</span>

添加Yarn目录下的Jar包即可。我是把所有包都添加上了。然后运行通过