Java classes reference each other

Question

I have two java class files. Each of them has methods the other one uses.

public class class1{
    class2 c2 = new class2(); 
    m1(){
        c2.ma(); 
        m2();
    }
    m2(){}
}

public class class2{
    class1 c1 = new class1();
    ma(){}
    mb(){
        c1.m2();
    }
}

The lines

class1 c1 = new class1();  

and

class2 c2 = new class2();  

refer to each other causing an infinite loop, resulting in a java.lang.StackOverflowError error.

Is there some way to have the classes refer to each other or do I have no choice but to transfer all of my methods into a single class?

Answer 1

As is said above, this is a sign of code smell.

Having a setter to set the method afterwards is not satisfactory, as you have an object in an indeterminate state, until the setters are called.

Although using a dependency framework such as Spring can help solve the above problem, if you use constructor injection, then you cannot have cyclic dependencies either! But at least when a bean is injected, you are sure it is not half constructed.

If you don't want to use a dependency injection framework, consider a factory pattern where both objects are created by a factory method, which returns a tuple (or a container object in the case of Java which has no native support for tuples) containing the fully constructed objects.