Function which can accept one or two parameter but not more than two

Question

I am trying to create a method which should accept minimum one and maximum two parameters. First parameter is must but second is optional.

I've tried following

myFunction(String param1, String param2){

}

But in this case both parameter need to be passed, which I don't want.

myFunction(String... params){
}

In this case it can accept more than two parameters also, which also I don't want.

Could someone please tell if it's accomplished in java?

I think it's not easy in java. You can achieve this type of behavior using function overloading with two methods and different arguments. — Sandeep Kokate, Nov 08 '17 at 08:37
@SandeepKokate: I'm not sure in what way that counts as "not easy" to be honest... — Jon Skeet, Nov 08 '17 at 08:38

Henrik Aasted Sørensen · Accepted Answer · 2017-11-08T08:37:12.677

5

Overload the method:

myFunction(String param1){
  ...
}

myFunction(String param1, String param2){
  ...
}

Consider making the "one parameter version" invoke the other version with a default value for the second parameter to simplify things.

edited Nov 08 '17 at 08:37

answered Nov 08 '17 at 08:35

Henrik Aasted Sørensen

6,966
11
51
60

This could be done, however in this case I need to duplicate my whole logic. – Mehraj Malik Nov 08 '17 at 08:36
2

@MehrajMalik: In most cases, you'd just make the single-parameter overload call the two-parameter overload with a default value. No duplication needed. If you need to know which overload was called, create a third private method that the first two call, with three parameters: `param1`, `param2`, `param2UserSupplied` (the last being a boolean) or similar. – Jon Skeet Nov 08 '17 at 08:37

Tim Biegeleisen · Answer 2 · 2017-11-08T08:42:36.117

1

In this exact case, since both possible parameters are strings, you could refactor your method to accept an array of strings, and then validate inside the method, e.g.

void myMethod (String... params) throws IllegalArgumentException {
    if (params == null || params.length < 1 ||
        params.length > 2 || params[0] == null) {
        throw new IllegalArgumentException("wrong no. of arguments");
    }
}

edited Nov 08 '17 at 08:42

answered Nov 08 '17 at 08:38

Tim Biegeleisen

502,043
27
286
360

Sync · Answer 3 · 2017-11-08T08:45:27.927

1

By overloading methods, you can achieve this with the following:

void foo(String param1, String param2) {
    // your logic here
}

void foo(String param1) {
    foo(param1, DEFAULT_VALUE_FOR_PARAM2);
}

Please see this answer for a complete overview of what is possible with optional arguments within Java.

edited Nov 08 '17 at 08:45

answered Nov 08 '17 at 08:39

Sync

3,571
23
30

Skytrace · Answer 4 · 2017-11-08T08:43:45.440

0

Maby will good to use overload approach? create two methods with same name but wit different attribute numbers

myFunction(param1)
myFunction(para1,param2)

Also, you can move the same logic from on abstract level, and use them on your myFunction().

edited Nov 08 '17 at 08:43

answered Nov 08 '17 at 08:38

Skytrace

58
4

Function which can accept one or two parameter but not more than two

4 Answers4