Read values wrapped in Hadoop ArrayWritable - hadoop

Question

I am new to Hadoop and Java. My mapper outputs text and Arraywritable. I having trouble to read ArrayWritable values. Unbale to cast .get() values to integer. Mapper and reducer code are attached. Can someone please help me to correct my reducer code in order to read ArrayWritable values?
public static class Temp2Mapper extends Mapper<LongWritable, Text, Text, ArrayWritable>{
private static final int MISSING=9999;
#Override public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException{
String line = value.toString();
String date = line.substring(07,14);
int maxTemp,minTemp,avgTemp;
IntArrayWritable carrier = new IntArrayWritable();
IntWritable innercarrier[] = new IntWritable[3];
maxTemp=Integer.parseInt(line.substring(39,45));
minTemp=Integer.parseInt(line.substring(47,53));
avgTemp=Integer.parseInt(line.substring(63,69));
if (maxTemp!= MISSING)
innercarrier[0]=new IntWritable(maxTemp); // maximum Temperature
if (minTemp!= MISSING)
innercarrier[1]=new IntWritable(minTemp); //minimum temperature
if (avgTemp!= MISSING)
innercarrier[2]=new IntWritable(avgTemp); // average temperature of 24 hours
carrier.set(innercarrier);
context.write(new Text(date), carrier); // Output Text and ArrayWritable
}
}
public static class Temp2Reducer
extends Reducer<Text, ArrayWritable, Text, IntWritable>{
#Override public void reduce(Text key, Iterable<ArrayWritable> values, Context context )
throws IOException, InterruptedException {
int max = Integer.MIN_VALUE;
int[] arr= new int[3];
for (ArrayWritable val : values) {
arr = (Int) val.get(); // Error: cannot cast Writable to int
max = Math.max(max, arr[0]);
}
context.write( key, new IntWritable(max) );
}
}

Answer 1

ArrayWritable#get method returns an array of Writable.
You can't cast an array of Writable to int. What you can do is:
iterate over this array
cast each item (which will be of type Writable) of the array to IntWritable
use IntWritable#get method to get the int value.
for (ArrayWritable val: values) {
for (Writable writable: val.get()) { // iterate
IntWritable intWritable = (IntWritable)writable; // cast
int value = intWritable.get(); // get
// do your thing with int value
}
}