checkers.nullness.quals

Annotation Type AssertNonNullIfTrue

public @interface AssertNonNullIfTrue

Indicates that if the method returns true, then the value expressions are non-null.

Method parameters: A common example is that the equals method is annotated as follows:

   @AssertNonNullIfTrue("#0")
   public boolean equals(@Nullable Object obj) { ... }

because, if equals returns true, then the first (#0) argument to equals was not null.

Fields: The value expressions can refer to fields, even private ones. For example:

   @AssertNonNullIfTrue("this.derived")
   public boolean isDerived() {
     return (this.derived != null);
   }

As another example, an Iterator may cache the next value that will be returned, in which case its hasNext method could be annotated as:

   @AssertNonNullIfTrue("next_cache")
   public boolean hasNext() {
     if (next_cache == null) return false;
     ...
   }

An AssertNonNullIfTrue annotation that refers to a private field is useful for verifying that client code performs needed checks in the right order, even if the client code cannot directly affect the field.

Method calls: If File.isDirectory() returns true, then File.list() returns non-null, and File.listFiles() returns non-null. You can express this relationship as:

   @AssertNonNullIfTrue({"list()","listFiles()"})
   public boolean isDirectory() { ... }

See Also:

NonNull, AssertNonNullIfFalse, NullnessChecker

See the Checker Framework manual:

Nullness Checker

Required Element Summary

Required Elements

Modifier and Type	Required Element and Description
String[]	value Java expression(s) that are non-null after the method returns true.

Element Detail

value

public abstract String[] value

Java expression(s) that are non-null after the method returns true.

See Also:

Syntax of Java expressions