Shakthydoss

Reading a file or reading multiple files from a (single)directory is such a easy task in Java. As every Java programmers know how use the method listFiles() to achieve the above mentioned task. Headache comes only when you try to read multiple files from multiple directory.

Well in this post I document my simple logic to read Multiple files from From Multiple directory. The pictorial representation of reading multiple files from single directory is show below.

Reading Multiple from single directory Case 1

Usual logic followed by most Java programmer to read multiple files is

Now lets make the scenario bit complicated that is reading multiple file from multiple directory. The pictorial representation is shown below.

Reading Multiple files from Multiple directories Case 2

The above diagram show that the main folder named ABC contain sub-folder A,B,C and each sub-folder contain multiple files that has to be read.

Consider little more complicated scenario that is a sub-folder containing multiple files along with another folder which has got another set of multiple files that has to be read. Simplified pictorial representation is shown below.

Reading Multiple files from Multiple directories Case 3

So for above case reading process should traversal to A.1 from A also then to Folder B and so on …

Simplest way to resolve the above two cases(2 & 3) is get all the directories on first traversal then put those directories in an array along with their path. Then repeat case 1 step for each directory in array. This could not be the solution if no of directories (sub-folder or) is large in number and you need to have parallel logic to handle sub-sub-folders which may  increase the process cycle exponentially.

Finally here I propose  my simple logic to solve all the above cases. Technique behind the logic is nothing superficially , I just kept the reading file process and directory traversal process separately by means by function. This help me to keep track of traversal with minimum process cycles.