Android.os.NetworkOnMainThreadException

I am using the APDE app on my Android mobile to program an app.

I am trying to use loadStrings(); to get data from my website.

If I use the loadStrings in setup() it works fine or on a function which caused by a change in variable it also works.

But if I try loadStrings in the mousePressed function then I get the Android.os.NetworkOnMainThreadException error.

Any ideas?