public class A{
    private static A a = new A();
    private A(){};
    public static A getA(){
        return a;
    }
}
public class B{
    private static B b = null;
    private B(){};
    public static B getB(){
        b = new B();
        return b;
    }
}
public class C{
    private static C c = null;
    static{
        c = new C();
    }
    private C(){};
    public static C getC(){
        return c;
    }
}