Some ideas:

• The usual approach in cases like this (looks like Command pattern to me) is passing additional parameters in the constructor. In your case, that means adding otherArgument to B during construction.

• Turning the logic around might open up some options. For instance moving doStuff to AParams:

    for (String arg : listOfArgs) {
        AParams p = AParams.create(arg, otherArgument));
        for (A a : listOfA) {
            p.doStuff(a); // Let AParams to the lifting depending on type of A
        }
    }
  

• Alternatively you can swallow your pride and check with instanceof in the loop and set otherArgument manually before calling doStuff.

If the above is not possible, then you have no choice except doing what you're doing (broadening the parameter argument). Don't overanalyze this stuff.

• The usual approach in cases like this (Command patternish) is passing additional parameters in the constructor. In your case, that means adding otherArgument to B during construction.

• Turning the logic around might open up some options. For instance moving doStuff to AParams:

    for (String arg : listOfArgs) {
        AParams p = AParams.create(arg, otherArgument));
        for (A a : listOfA) {
            p.doStuff(a); // Let AParams to the lifting depending on type of A
        }
    }
  

• Alternatively you can swallow your pride and check with instanceof in the loop and set otherArgument manually before calling doStuff.

If the above is not possible, then you have no choice except doing what you're doing (broadening the parameter argument). Don't overanalyze this stuff.

Some ideas:

The usual approach in cases like this (looks like Command pattern to me) is passing additional parameters in the constructor. In your case, that means adding otherArgument to B during construction.

Turning the logic around might open up some options. For instance moving doStuff to AParams:

for (String arg : listOfArgs) {
    AParams p = AParams.create(arg, otherArgument));
    for (A a : listOfA) {
        p.doStuff(a); // Let AParams to the lifting depending on type of A
    }
}

Alternatively you can swallow your pride and check with instanceof in the loop and set otherArgument manually before calling doStuff.

If that's not possible then you have no choice except doing what you're doing (broadening the parameter argument). Don't overanalyze this stuff.

Some ideas:

• The usual approach in cases like this (looks like Command pattern to me) is passing additional parameters in the constructor. In your case, that means adding otherArgument to B during construction.

• Turning the logic around might open up some options. For instance moving doStuff to AParams:

    for (String arg : listOfArgs) {
        AParams p = AParams.create(arg, otherArgument));
        for (A a : listOfA) {
            p.doStuff(a); // Let AParams to the lifting depending on type of A
        }
    }
  

• Alternatively you can swallow your pride and check with instanceof in the loop and set otherArgument manually before calling doStuff.

If the above is not possible, then you have no choice except doing what you're doing (broadening the parameter argument). Don't overanalyze this stuff.