Details
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Bug
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Resolution: Fixed
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P4
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8
Description
JLS8 4.12.4 defines "effectively final" for a local variable in a rather roundabout fashion:
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A local variable or a method, constructor, lambda, or exception parameter is effectively final if it is not declared final but it never occurs as the left hand operand of an assignment operator (§15.26) or as the operand of a prefix or postfix increment or decrement operator (§15.14, §15.15).
In addition, a local variable whose declaration lacks an initializer is effectively final if all of the following are true:
• It is not declared final.
• Whenever it occurs as the left-hand operand of an assignment operator, it is definitely unassigned and not definitely assigned before the assignment; that is, it is definitely unassigned and not definitely assigned after the right-hand operand of the assignment (§16 (Definite Assignment)).
• It never occurs as the operand of a prefix or postfix increment or decrement operator.
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Here is a clearer version: (Note the switch from "declaration" to "declarator", and "assignment operator" to "assignment expression". '=' is an assignment operator; it is used in both assignment expressions and local variable declarators, but those are not the same thing.)
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• A local variable whose declarator has an initializer (14.4.2) is effectively final if all of the following are true:
- It is not declared final.
- It never occurs as the left hand side in an assignment expression (§15.26). (Note that the local variable declarator containing the initializer is _not_ an assignment expression.)
- It never occurs as the operand of a prefix or postfix increment or decrement operator (§15.14, §15.15).
• A local variable whose declarator lacks an initializer is effectively final if all of the following are true:
- It is not declared final.
- Whenever it occurs as the left hand side in an assignment expression, it is definitely unassigned and not definitely assigned before the assignment; that is, it is definitely unassigned and not definitely assigned after the right hand side of the assignment expression (§16 (Definite Assignment)).
- It never occurs as the operand of a prefix or postfix increment or decrement operator.
• A method, constructor, lambda, or exception parameter is treated, for the purpose of determining whether it is effectively final, as a local variable whose declarator has an initializer.
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A local variable or a method, constructor, lambda, or exception parameter is effectively final if it is not declared final but it never occurs as the left hand operand of an assignment operator (§15.26) or as the operand of a prefix or postfix increment or decrement operator (§15.14, §15.15).
In addition, a local variable whose declaration lacks an initializer is effectively final if all of the following are true:
• It is not declared final.
• Whenever it occurs as the left-hand operand of an assignment operator, it is definitely unassigned and not definitely assigned before the assignment; that is, it is definitely unassigned and not definitely assigned after the right-hand operand of the assignment (§16 (Definite Assignment)).
• It never occurs as the operand of a prefix or postfix increment or decrement operator.
--
Here is a clearer version: (Note the switch from "declaration" to "declarator", and "assignment operator" to "assignment expression". '=' is an assignment operator; it is used in both assignment expressions and local variable declarators, but those are not the same thing.)
--
• A local variable whose declarator has an initializer (14.4.2) is effectively final if all of the following are true:
- It is not declared final.
- It never occurs as the left hand side in an assignment expression (§15.26). (Note that the local variable declarator containing the initializer is _not_ an assignment expression.)
- It never occurs as the operand of a prefix or postfix increment or decrement operator (§15.14, §15.15).
• A local variable whose declarator lacks an initializer is effectively final if all of the following are true:
- It is not declared final.
- Whenever it occurs as the left hand side in an assignment expression, it is definitely unassigned and not definitely assigned before the assignment; that is, it is definitely unassigned and not definitely assigned after the right hand side of the assignment expression (§16 (Definite Assignment)).
- It never occurs as the operand of a prefix or postfix increment or decrement operator.
• A method, constructor, lambda, or exception parameter is treated, for the purpose of determining whether it is effectively final, as a local variable whose declarator has an initializer.