Why is there no type conversion exception in this code?

Question

This is from Thinking in Java

class Snow {}
class Powder extends Snow {}
class Light extends Powder {}
class Heavy extends Powder {}
class Crusty extends Snow {}
class Slush extends Snow {}

public class AsListInference {
    public static void main(String[] args) {
        //The book says it won't compile, but actually it does.
        List<Snow> snow2 = Arrays.asList(new Light(), new Heavy());
    }
}

Here is my Java enviroment:

1. java version "1.8.0_60"
2. Java(TM) SE Runtime Environment (build 1.8.0_60-b27)
3. Java HotSpot(TM) 64-Bit Server VM (build 25.60-b23, mixed mode)

Answer 1

Actually, the book is right. The difference here is the Java version.

Thinking in Java targets Java 5/6 (as per the cover). For this version of Java (and with Java 7 also), the snippet won't compile with javac. The error is:

incompatible types: java.util.List<Powder> cannot be converted to java.util.List<Snow>

With Java 8, this compiles just fine: the type-inference system was improved.