You can simply use split method from String class.
Split file=android.txt&data=it contains android data
on & to get array of "file=android.txt" and "data=it contains android data".
Then you can split each of this elements on = so
file=android.txt -> file, android.txt
data=it contains android data -> data, it contains android data
So your code can look like
foreach element in data.split(&)
array = element.split(=)
get second element from array
solved Split string using substring [closed]