Why am I getting an AssertionError when assigning Arrays.asList() to var directly?

Question

I\'m trying to understand local variable type inference in Java 10.

1. The code below works perfectly during compilation and runtime:

   List list1 =         
   
   
           

Answer 1

This is a bug in Java 10 compiler: https://bugs.openjdk.java.net/browse/JDK-8199910

It is only reproduced when javac is called with a -g flag.

Possible workarounds:

1. Do not use the -g flag
   • If you use IDEA: Settings → Build, Execution, Deployment → Compiler → Java Compiler → Uncheck "Generate Debugging Info"
2. Do not use var with intersection types (use explicit types):
   • List<Object> list = Arrays.asList(1L, 2.0F, "3");
   • var list = Arrays.<Object> asList(1L, 2.0F, "3");
3. Use Eclipse which has its own compiler

UDPATE:

The bug was fixed in JDK 10.0.2.

Answer 2

This is a bug of openjdk, see this:

Javac should skip non-denotable types in the LocalVariableTypeTable attribute