how to read 100 text files from a folder or directory and write the data into a single file.using java programming?

i have multiple(app..100) text files which has data in the form of intgers consisting of 3 columns and app..3000 rows.the data in the 1st 2 columns is similar for every file.so it the 3rd column value that keeps on changing for every file.i have read the data from all the files and write them into a single file..the target file should have the 1st two columns the same as in the 100 files..and the data is to be writen from 3rd column.(column wise)