java.lang.Exception: java.lang.ArrayIndexOutOfBoundsException: 7 MapReduce代码报这样的错的解决方法

在 MapReduce 报数组越界问题：
在编写MapReduce 的代码块的时候报数组越界，主要是因为在处理大量的数据的时候，不能100%确定这大量数据中不存在空行，所以必须要先判断是否为空：

 at org.apache.hadoop.mapred.LocalJobRunner$Job.runTasks(LocalJobRunner.java:462)
 at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:522)
Caused by: java.lang.ArrayIndexOutOfBoundsException: 7
 at Market.Market_Mapper.map(Market_Mapper.java:24)
 at Market.Market_Mapper.map(Market_Mapper.java:10)
 at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:146)
 at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:787)
 at org.apache.hadoop.mapred.MapTask.run(MapTask.java:341)
 at org.apache.hadoop.mapred.LocalJobRunner$Job$MapTaskRunnable.run(LocalJobRunner.java:243)
 at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
 at java.util.concurrent.FutureTask.run(FutureTask.java:266)
 at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
 at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
 at java.lang.Thread.run(Thread.java:745)
2019-09-06 22:09:32,244 INFO mapreduce.Job: Job job_local1935223179_0001 running in uber mode : false
2019-09-06 22:09:32,245 INFO mapreduce.Job:  map 0% reduce 0%
2019-09-06 22:09:32,246 INFO mapreduce.Job: Job job_local1935223179_0001 failed with state FAILED due to: NA
2019-09-06 22:09:32,258 INFO mapreduce.Job: Counters: 0
false

做是否为空判断：

我的原来报错的代码：（就是把两个值没做判断直接给了key和value）

String[] str = line.split("\t");
Text k =new Text();
IntWritable v=new IntWritable();

    k.set(str[7]);
    v.set(1);
    context.write(k,v);

要做不为空的判断，对的代码：

if( str.length>7  &&  !str[7].isEmpty()  &&   !str[6].isEmpty())
{
    k.set(str[7]);
    v.set(1);
    context.write(k,v);
}

最好用 ！.isEmpty() 这种判断方式，不要用别的！