java - hadoop worldcount程序 输出路径报错 :目录已经存在？

Question

运行worldcount 程序一直报错。说输出目录已经存在！
一开始的路径是/test/output 报错/test/output already exists，我删除了output 又报错：/test already exists，，然后我新建了一个newoutput 又报错 /test/newouput already exists。。现在我把输出路径放到根目录下还是already exists！！！这个是什么情况？？？
Exception in thread "main" org.apache.hadoop.mapred.FileAlreadyExistsException: Output directory file:/ already exists
at org.apache.hadoop.mapreduce.lib.output.FileOutputFormat.checkOutputSpecs(FileOutputFormat.java:146)
at org.apache.hadoop.mapreduce.JobSubmitter.checkSpecs(JobSubmitter.java:266)
at org.apache.hadoop.mapreduce.JobSubmitter.submitJobInternal(JobSubmitter.java:139)
at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1290)
at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1287)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Unknown Source)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1657)
at org.apache.hadoop.mapreduce.Job.submit(Job.java:1287)
at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:1308)
at com.mzy.worldcount.WorldCount.main(WorldCount.java:87)

Answer 1

比如你想保存到 /temp/output目录下. 在/temp目录下必需要不存在output目录
rm -rf /temp/output
hadoop jar worldcount /temp/input /temp/output