instanceof in Java - why doesn't this compile? [duplicate]

Answer 1

It's a compilation error in accordance with JLS §15.20.2:

If a cast of the RelationalExpression to the ReferenceType would be rejected as a compile-time error, then the instanceof relational expression likewise produces a compile-time error. In such a situation, the result of the instanceof expression could never be true.

RelationalExpression is the first operand of instanceof and ReferenceType is the second.

Answer 2

In addition to the arshajii's answer if you want to avoid compile-time error and want run-time true/false result for checking whether var is instance of Character then use code like this:

if(var.getClass().isAssignableFrom(Character.class))
    System.out.println("var is a Character");
else
    System.out.println("var is NOT a Character");

As you would expect it will print:

var is NOT a Character