How can you extend Java to introduce passing by reference?

Question

Java is pass-by-value. How could you modify the language to introduce passing by reference (or some equivalent behavior)?

Take for example something like

<         


        

Answer 1

Using AtomicReference class as holder object.

public static void main(String[] args) {
    String variable="old";
    AtomicReference at=new AtomicReference(variable);
    passByReference(at);
    variable=at.get();
    System.out.println(variable);
}

public static void passByReference(AtomicReference at) {
  at.set("new");
}