I have a sequential file which is the output of hadoop map-reduce job. In this file data is written in key value pairs ,and value itself is a map. I want to read the value as a MAP object so that i can process it further.
Configuration config = new Configuration();
Path path = new Path("D:\\OSP\\sample_data\\data\\part-00000");
SequenceFile.Reader reader = new SequenceFile.Reader(FileSystem.get(config), path, config);
WritableComparable key = (WritableComparable) reader.getKeyClass().newInstance();
Writable value = (Writable) reader.getValueClass().newInstance();
long position = reader.getPosition();
while(reader.next(key,value))
{
System.out.println("Key is: "+textKey +" value is: "+val+"\n");
}
output of program: Key is: [this is key] value is: {abc=839177, xyz=548498, lmn=2, pqr=1}
Here i am getting value as string ,but i want it as a object of map.
Check the API documentation for SequenceFile#next(Writable, Writable)
while(reader.next(key,value))
{
System.out.println("Key is: "+textKey +" value is: "+val+"\n");
}
should be replaced with
while(reader.next(key,value))
{
System.out.println("Key is: "+key +" value is: "+value+"\n");
}
Use SequenceFile.Reader#getValueClassName to get the value type in the SequenceFile. SequenceFile have the key/value types in the file header.