Package org.checkerframework.checker.optional.qual

Annotation Interface RequiresPresent

@Documented @Retention(RUNTIME) @Target({METHOD,CONSTRUCTOR}) @PreconditionAnnotation(qualifier=Present.class) public @interface RequiresPresent
Indicates a method precondition: the specified expressions of type Optional must be present (i.e., non-empty) when the annotated method is invoked.

For example: 

 import java.util.Optional;

 import org.checkerframework.checker.optional.qual.RequiresPresent;
 import org.checkerframework.checker.optional.qual.Present;

 class MyClass {
   Optional<String> optId1;
   Optional<String> optId2;

   @RequiresPresent({"optId1", "#1.optId1"})
   void method1(MyClass other) {
     optId1.get().length()       // OK, this.optID1 is known to be present.
     optId2.get().length()       // error, might throw NoSuchElementException.

     other.optId1.get().length() // OK, this.optID1 is known to be present.
     other.optId2.get().length() // error, might throw NoSuchElementException.
   }

   void method2() {
     MyClass other = new MyClass();

     optId1 = Optional.of("abc");
     other.optId1 = Optional.of("def")
     method1(other);                       // OK, satisfies method precondition.

     optId1 = Optional.empty();
     other.optId1 = Optional.empty("abc");
     method1(other);                       // error, does not satisfy this.optId1 method precondition.

     optId1 = Optional.empty("abc");
     other.optId1 = Optional.empty();
     method1(other);                       // error. does not satisfy other.optId1 method precondition.
   }
 }
Do not use this annotation for formal parameters (instead, give them a @Present type). The @RequiresNonNull annotation is intended for non-parameter expressions, such as field accesses or method calls.
See the Checker Framework Manual:
Optional Checker

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Class
    Description
    static @interface 
    RequiresPresent.List
    A wrapper annotation that makes the RequiresPresent annotation repeatable.

  • Required Element Summary

    Required Elements
    Modifier and Type
    Required Element
    Description
    String[]
    value
    The Java expressions that that need to be Present.