"I call it my billion-dollar mistake. It was the invention of the null reference in 1965."
What is Infer:Eradicate?
Infer:Eradicate is a type checker for @Nullable annotations for Java. It is part of the Infer static analysis suite of tools. The goal is to eradicate null pointer exceptions.@Nullableannotations denote that a parameter, field or the return value of a method can be null. When decorating a parameter, this denotes that the parameter can legitimately be null and the method will need to deal with it. When decorating a method, this denotes the method might legitimately return null.
Starting from @Nullable-annotated programs, the checker performs a flow sensitive analysis to propagate the nullability through assignments and calls, and flags errors for unprotected accesses to nullable values or inconsistent/missing annotations. It can also be used to add annotations to a previously un-annotated program.
What is the @Nullable convention?
If you say nothing, you're saying that the value cannot be null. This is the recommended option when possible:
Program safely, annotate nothing!
When this cannot be done, add a @Nullable annotation before the type to indicate that the value can be null.
What is annotated?
Annotations are placed at the interface of method calls and field accesses:
- Parameters and return type of a method declaration.
- Field declarations.
Local variable declarations are not annotated: their nullability is inferred.
How is Infer:Eradicate invoked?
Eradicate can be invoked by adding the option
--eradicate to the checkers mode
as in this example:
The checker will report an error on the following program that accesses a nullable value without null check:
But it will not report an error on this guarded dereference:
Eradicate reports the following warnings.