The same developer has had IDEs for Java and PhoneGap available for some time, with a good number of installs and decent reviews for the Java version. I have both, but haven't really used them since I have more need for a general text editor. That said, with an external keyboard there's no reason these couldn't be quite functional for programming.

There are other development options on Android devices as well, including Terminal IDE (https://play.google.com/store/apps/details?id=com.spartacusr...) for a full command-line based development environment and DroidEdit (Free and Pro versions) (https://play.google.com/store/apps/details?id=com.aor.droide...) for a more GUI-oriented programmer's text editor.