How to pass array parameter with inline declare?

Question

I have a method as

private void show(Object[] arr) {
  for (Object o : arr) {
    System.out.println(o);
  }
}

I would like to call this method as

// belows are not valid but I'd like to achieve 
show({1,2,3});
show(new String["a","b","c"])

but I don't want to create an array to call this method. (Please don't be suggest to change the signature of my show method.This is just an example.Actual method that I use is from 3rd party lib.)

How can I achieve this by utility classes or anything else?

use varargs : http://stackoverflow.com/questions/766559/when-do-you-use-varargs-in-java — Rahul, Mar 15 '17 at 05:22
`show(Object... arr)`? Then you can say `show(1, 2, 3)` or `show("a", "b", "c")` ... etc — MadProgrammer, Mar 15 '17 at 05:23
@Cataclysm If you can't change the `show` method then you're stuck having to declare a variable, `show(new Integer[] {1, 2, 3})` — MadProgrammer, Mar 15 '17 at 05:24
@MadProgrammer sorry .. I can't change my method signature because my actual method that I use is from third pary lib. — Cataclysm, Mar 15 '17 at 05:24
@MadProgrammer thanks `show(new Integer[] {1, 2, 3})` this is what I need. — Cataclysm, Mar 15 '17 at 05:37

score 4 · Answer 1 · answered Mar 15 '17 at 05:25

4

You can either use varargs as mentioned in the comments or declare the array this way:

show(new String[] {"a","b","c"})

answered Mar 15 '17 at 05:25

dpr

10,591
3
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anacron · Answer 2 · 2017-03-15T05:52:51.777

3

Create a varargs wrapper method:

private void myShow(Object... arr){
    show(arr);
}

// No change to your existing 3rd party method:
private void show(Object[] arr) {
  for (Object o : arr) {
    System.out.println(o);
  }
}

You can then call the wrapper method like this:

myShow("a","b","c");
myShow(1,2,3,4);

Hope this helps!

edited Mar 15 '17 at 05:52

answered Mar 15 '17 at 05:23

anacron

6,443
2
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By OP : (Please don't be suggest to change the signature of my show method.This is just an example.) – Cataclysm Mar 15 '17 at 05:23
This does not change the signature. A vararg is an array still. – user681574 Mar 15 '17 at 05:24
@Cataclysm, That doesn't change the signature. The args still remain an array type. – anacron Mar 15 '17 at 05:25
I can't change my method signature because my actual method that I use is from third pary lib – Cataclysm Mar 15 '17 at 05:25
1

It does change the signature, without modify the method, you can't use varargs against it, so the OP could use `show(1, 2, 3, 4)` with their current implementation :P – MadProgrammer Mar 15 '17 at 05:26

Rafael Lima · Accepted Answer · 2017-03-15T05:30:00.930

2

What you are looking for is not a way to pass an array to a method without declare it, you are looking for a "single line data instatiation for array"... or by the real name "in-line declare"

show(new Object[]{"a","b","c"});

edited Mar 15 '17 at 05:30

answered Mar 15 '17 at 05:24

Rafael Lima

3,079
3
41
105

OK ... I got it `in-line declare`. I don't know how to call this :) – Cataclysm Mar 15 '17 at 05:35

score 0 · Answer 4 · answered Mar 15 '17 at 05:25

0

You can accomplish this by using varargs. A simple edit to your function will not only allow an array of objects but allow you to accomplish what you are looking for.

Instead of using Object[] use Object...

answered Mar 15 '17 at 05:25

Cameron

58
7

How to pass array parameter with inline declare?

4 Answers4