Text to String map reduce - mapreduce

Question

I am trying to split a string using mapreduce2(yarn) in Hortonworks Sandbox.
It throws a ArrayOutOfBound Exception if I try to access val[1] , Works fine with when I don't split the input file.
Mapper:
public class MapperClass extends Mapper<Object, Text, Text, Text> {
private Text airline_id;
private Text name;
private Text country;
private Text value1;
public void map(Object key, Text value, Context context)
throws IOException, InterruptedException {
String s = value.toString();
if (s.length() > 1) {
String val[] = s.split(",");
context.write(new Text("blah"), new Text(val[1]));
}
}
}
Reducer:
public class ReducerClass extends Reducer<Text, Text, Text, Text> {
private Text result = new Text();
public void reduce(Text key, Iterable<Text> values, Context context)
throws IOException, InterruptedException {
String airports = "";
if (key.equals("India")) {
for (Text val : values) {
airports += "\t" + val.toString();
}
result.set(airports);
context.write(key, result);
}
}
}
MainClass:
public class MainClass {
public static void main(String[] args) throws IOException, ClassNotFoundException, InterruptedException {
Configuration conf = new Configuration();
#SuppressWarnings("deprecation")
Job job = new Job(conf, "Flights MR");
job.setJarByClass(MainClass.class);
job.setMapperClass(MapperClass.class);
job.setReducerClass(ReducerClass.class);
job.setNumReduceTasks(0);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(Text.class);
job.setInputFormatClass(KeyValueTextInputFormat.class);
FileInputFormat.addInputPath(job, new Path(args[0]));
FileOutputFormat.setOutputPath(job, new Path(args[1]));
System.exit(job.waitForCompletion(true) ? 0 : 1);
}
}
Can you help?
Update:
Figured out that it doesn't convert Text to String.

Answer 1

If the string you are splitting does not contain a comma, the resulting String[] will be of length 1 with the entire string in at val[0].
Currently, you are making sure that the string is not the empty string
if (s.length() > -1)
But you are not checking that the split will actually result in an array of length more than 1 and assuming that there was a split.
context.write(new Text("blah"), new Text(val[1]));
If there was no split this will cause an out of bounds error. A possible solution would be to make sure that the string contains at least 1 comma, instead of checking that it is not the empty string like so:
String s = value.toString();
if (s.indexOf(',') > -1) {
String val[] = s.split(",");
context.write(new Text("blah"), new Text(val[1]));
}