Well, just record some things, and save it when you can't find the place. 1.Try {.....} catch (execption e) {... Re-assay}, for example: int i = 1; try {i = 100/0;} catch (exception e) {system.out.println E.GetMessage ()); i = 5;} system.out.println (i); 2.Try {// Explosive Experts} catch () {} finally {// Exception also execute}