A syntax-directed keyboard extension for writing source code on touchscreen devices

As touchscreen mobile devices grow in popularity, it is inevitable that software developers will eventually want to write code on them. However, writing code on a soft (or virtual) keyboard is cumbersome due to the device size and lack of tactile feedback. We present a soft syntax-directed keyboard extension to the QWERTY keyboard for Java program input on touchscreen devices and evaluate this keyboard with Java programmers. Our results indicate that a programmer using the keyboard extension can input a Java program with fewer errors and using fewer keystrokes per character than when using a standard soft keyboard alone. In addition, programmers maintain an overall typing speed in words per minute that is equivalent to that on the standard soft keyboard alone. The keyboard extension was shown to be mentally, physically, and temporally less demanding than the standard soft keyboard alone when inputting a Java program.