Running C/C++ executable in my Java code

[selecao]

I am unable to run a C/C++ executable in my java code can any one pls hep me out.....while i amable to run other java codes through the same code

A section of the code is copied below

int i=c1.getSelectedIndex();
Runtime r=Runtime.getRuntime();
try
{
if(i==3)
{
r.exec("./root/a.out");
System.exit(0);
}

}catch(Exception e){}

No action takes place even when the value of i=3
Pls reply quick..Iys kinda important