Byte Buddy Android allows you to generate classes on Android and to load them into the current Android VM process. To load classes on Android, the AndroidClassLoadingStrategy must be used when loading a dynamic type:

ClassLoadingStrategy strategy = new AndroidClassLoadingStrategy.Wrapping(context.getDir(
  "generated", 
  Context.MODE_PRIVATE));

Class<?> dynamicType = new ByteBuddy()
  .subclass(Object.class)
  .method(ElementMatchers.named("toString"))
  .intercept(FixedValue.value("Hello World!"))
  .make()
  .load(getClass().getClassLoader(), strategy)
  .getLoaded();
assertThat(dynamicType.newInstance().toString(), is("Hello World!"))

Using the strategy requires Android with support for API version 21 or later. A wrapping and an injecting class loading strategy is offered, similar to Byte Buddy's standard strategies. On Android, it is not possible to transform loaded classes or to register a Java agent.