Question

I just wantto know how can I know the default program associated with any external program/file. For ex-by default, a java file opens with which program? This I have to know using a Java program itself.

Answer 1

On windows:

Runtime rt = Runtime.getRuntime();
Process pr = rt.exec("ftype > %YOUR_DIRECTORY%\\type_program.properties");
Properties prop = new Properties();
InputStream in = getClass().getResourceAsStream("%YOUR_DIRECTORY%\\type_program.properties");
prop.load(in);

on Unix\Linux:

you can use file command for specific extension and get the corresponding mapping.

at this point you got all the mappings in your properties object.
enjoy!