The spread operator passes the array as if it was a set of individual parameters. The asList method expects a vararg of the individual elements that will be used to create the list. You can think of it as unpacking the array into separate parameters, which is why it can be regarded as a destructuring operator.

It allows you to pass an array directly to the varargs as an array. What if you already have the arguments in an array? This is where the spread operator, * comes in. If you pass parameters to a vararg one by one it builds an array for you to hold them. In Java, vararg parameters must be declared as the last parameter.There is one special type of destructuring designed to make it easier to use varargs.

Basically, it copies all elements from the original array to a new one and passes the copied one to the sum() function.

Index 13 and 14 are loading two parameters into the operand stack and then passing them to the pyOf(int, int) method. Then it will pass the new array as the vararg parameter: 12: aload_0 // loads the intġ5: invokestatic #71 // Method java/util/pyOf:([II)[I Kotlin will use the pyOf(array, length) method to first create a copy of the spreading array. Moreover, when using the spread operator: val numbers = intArrayOf(1, 2)

Also, the ACC_VARARGS flag specifies that the function accepts a variable-length parameter. After that, we can take a peek at the generated bytecode via javap: $ javap -c -p -v įlags: (0x0099) ACC_PUBLIC, ACC_STATIC, ACC_FINAL, ACC_VARARGSĪs shown above, the vararg parameter is defined as a vararg in Java.

Kotlin list to vararg