It's important to note that it's the Java language, but not the Java bytecode or Java Virtual Machine that are used in Android. It could easily have been really any language that Google wished to provide a compiler for towards their custom bytecode/VM. It was somewhat arbitrarily the Java language but was a good business choice IMHO due to the prevalence of Java developers in the market.
Secondly, there's nothing stopping you from writing your apps in C/C++ to get whatever sort of response you need.