In Java, there is no way to specify that you want a method to be inlined.
However, the JVM does inlining automatically for you. If you have for example a JavaBean class with simple getters, like this:
then the JVM will be smart enough to inline those getter methods at the places you call them. So calling those getter methods will be just as efficient as accessing the member variables directly.
In other words, normally you don't have to worry about inlining yourself in Java.