Is it possible to initialize an companion object before the init block in a Kotlin class? If so, how? If not, is there a way to accomplish the same thing.
I have the following scenario,
class A(val iname: String) {
init {
foo.add(this)
}
companion object B {
@JvmField val STATIC = A("hi")
@JvmField val foo = mutableListOf<A>()
}
fun printAllStatics() {
for (a in foo) {
print(a.iname)
}
}
}
并且调用printAllStatics会导致空指针异常.
The property initializers and init blocks are executed in exactly the same order in which they are placed in a class/object body. Here's an example:
companion object B {
init {
print("1 ")
}
@JvmField val foo = mutableListOf<A>().apply { print("2 ") }
@JvmField val bar = mutableListOf<A>().apply { print("3 ") }
init {
print("4")
}
}
它将打印1 2 3 4个
So, in your case, swapping the two declarations in the companion object is enough:
companion object B {
@JvmField val foo = mutableListOf<A>()
@JvmField val STATIC = A("hi")
}