What is ... (3 dots) found in the Java source? Variadic arguments to know from

Trigger

I saw an argument of ... (3 dots) in the Java source.

java:What...What?

    private static void printArgs(String description, Object... args) {
        for (Object object : args) {
            System.out.println(object);
        }
    }

... (three points) represent variadic arguments.

Variadic arguments can specify multiple arguments of the specified type.

Try to specify the argument

        //This is OK
        printArgs("One", "Multiple");
        //This is also OK
        printArgs("Two", "Multiple", "Designation");
        //This is also OK
        printArgs("Three", "Multiple", "Designation", true);
        //This is OK
        printArgs("None");

result

One:Multiple
Two:Multiple designation
Three:Multiple specifications true
None: 

Variadic arguments are like defining an array.

Compiling a variadic method produces an array.

After compilation

    public void methodName(String description, Object[] vars)
The contents of the method.
    }

Variadic arguments can also be arrays.

You can also specify an array as an argument

//This is OK
methodName("Array", new int[]{1,2,3,4,5});
//Even this is OK
methodName("Array and one", new int[]{1,2,3,4,5}, "Multiple");

Variadic arguments have a rule of use.

** Do not overload with an array as an argument ** Reason: It will be the same when compiled

Do not overload with an array as an argument

    public void methodName(String description, Object... vars)
The contents of the method.
    }
    public void methodName(String description, Object[] vars)
The contents of the method.
    }

** Variadic argument must be specified at the end ** Reason: Maybe because you don't know how much is the value specified for the variadic argument

Variadic argument must be specified at the end

//I get a compile error in args, and in Eclipse I get this message:(Rough translation:Write the variadic argument at the end)
// 「The variable argument type Object of the method printArgs must be the last parameter」
    private static void printArgs2(Object... args, String description) {
The contents of the method.
    }

** Only one variable length argument can be specified ** Reason: Maybe you don't know where the first one is, and the first variadic argument isn't specified at the end.

Only one variable length argument can be specified

//I get a compile error in args2, and in Eclipse I get this message:
// 「The variable argument type Object of the method printArgs must be the last parameter」
    private static void printArgs2(String description, String... args2, Object... args) {
The contents of the method.
    }

//This will not result in a compile error
    private static void printArgs2(String description, String[] args2, Object... args) {
The contents of the method.
    }

bonus

How to test private methods with arrays and variadic arguments in JUnit-Qiita

: sunny: Site explaining variadic arguments: sunny:

-Java Variadic Memo (Hishidama's Java VarArgs Memo) -[Java] Precautions when arranging variable-length argument parameters --Qiita