Apparent variable 'index' was found in a static scope but doesn't refer to a local variable, static field or class. Possible causes:
You attempted to reference a variable in the binding or an instance variable from a static context.
You misspelled a classname or statically imported field. Please check the spelling.
You attempted to use a method 'index' but left out brackets in a place not allowed by the grammar.
at line: 5, column: 39