In education, we have noticed a significant gap between the ability of students to program in an educational visual programming environment and the ability to write code in a professional programming environment. The aim of our research was to verify the methodology of transition from visual programming of mobile applications in MIT App Inventor 2 to textual programming in the Android Studio using the Java Bridge tool as a mediator of knowledge transfer. We have examined the extent, to which students will be able to independently program own mobile applications after completing the transition from visual to textual programming using the mediator. To evaluate the performance of students, we have analysed qualitative data from teaching during 1 school year and determined the degree of achievement of educational goals according to Bloom's taxonomy. The results suggest that students in the secondary education can acquire advanced skills in programming mobile applications in a professional programming environment, when they have knowledge of visual programming in an educational programming environment, and a suitable mediator is used to transfer such knowledge into a new context.