Java Reference
In-Depth Information
14.20.3.
try
-with-resources
A
try
-with-resources statement is parameterized with variables (known as
resources
) that
are initialized before execution of the
try
block and closed automatically, in the reverse or-
der from which they were initialized, after execution of the
try
block.
catch
clauses and a
finally
clause are often unnecessary when resources are closed automatically.
TryWithResourcesStatement:
try
ResourceSpecification Block Catches
opt
Finally
opt
ResourceSpecification:
(
Resources
;
opt
)
Resources:
Resource
Resource
;
Resources
Resource:
VariableModifiers
opt
Type VariableDeclaratorId
=
Expression
A
ResourceSpecification
declares one or more local variables with initializer expressions
to act as
resources
for the
try
statement.
not explicitly declared
final
.
The type of a variable declared in a
ResourceSpecification
must be a subtype of
AutoCloseable
, or a compile-time error occurs.
The scope and shadowing of a variable declared in a
ResourceSpecification
is specified in
It is a compile-time error for a
ResourceSpecification
to declare two variables with the
same name.
Resources are initialized in left-to-right order. If a resource fails to initialize (that is, its ini-
tializer expression throws an exception), then all resources initialized so far by the
try
-with-
resources statement are closed. If all resources initialize successfully, the
try
block executes
as normal and then all non-null resources of the
try
-with-resources statement are closed.
Resources are closed in the reverse order from that in which they were initialized. A re-
source is closed only if it initialized to a non-null value. An exception from the closing
of one resource does not prevent the closing of other resources. Such an exception is
sup-
pressed
if an exception was thrown previously by an initializer, the
try
block, or the closing
of a resource.
