In the US, 21 CFR 101 provides reference amounts for serving sizes, which are usually followed somewhat closely (I wasn't able to determine if they are required by law) by food manufacturers.
In the specific case of rice, the standard serving size is "140 g prepared; 45 g dry" listed in the format "_ cup(s) (_ g)".
Usually, the nutritional label on the actual product package (no comment on databases on random websites and apps) will provide information about whether it is referring to prepared or "raw" state, or will provide both. The prepared state may include ingredients not provided in the package.
For example, Cheerios has a serving size of "1 cup (28 g)", dry, and additionally provides a column with values for "with 1/2 cup skim milk".
Kraft Macaroni & Cheese Dinner gives the serving size as "2.5 oz (70 g / about 1/2 box) (Makes about 1 cup)", and provides columns for "as packaged" and "as prepared". Different pictures I found of the nutrition information and directions varied widely as to the calories of the "as prepared" column and the amount of butter called for; presumably these will match on any given box.
I wasn't able to find any pictures of real nutrition labels for packages of plain rice.
Google allows you to specify "raw" or "cooked" when searching for the nutrition information of rice - according to it, 100 grams of cooked long-grain brown rice has 111 calories, and 100 grams of raw long-grain brown rice has 370 calories. When the measure is switched to one cup, the calories are 216 and 684 respectively, with the weights being 195 and 185 grams. So, if your app doesn't say, it should be easy to figure out which numbers track better with how many calories it actually says a cup of rice has.