Is "pass by reference" bad design?

So, I just started learning Java, and I discovered that there's no such thing as "pass by reference". I'm porting an application from C# to Java, and the original application has ints and doubles that are either "ref" or "out" parameters.

At first I thought I could pass in an "Integer" or a "Double", and since that was a Reference type, the value would be changed. But then I learned that those reference types are immutable.

So, then I made a "MutableInteger" class and a "MutableDouble" class, and I passed those into my functions. It works, but I guess I must be going against the original design intentions of the language.

Is "pass by reference" in general bad design? How should I change my way of thinking?

It seems reasonable to have a function like this:

bool MyClass::changeMyAandB(ref int a, ref int b)
{
    // perform some computation on a and b here

    if (success)
        return true;
    else return false;
}

Is that bad design?