...
According
...
to
...
The Java
...
Language
...
Specification
...
When used as a primary expression, the keyword
thisdenotes a value that is a reference to the object for which the instance method was invoked (§15.12), or to the object being constructed....The type of
thisis the class or interface type T within which the keywordthisoccurs....At run time, the class of the actual object referred to may be T, if T is a class type, or a class that is a subtype of T.
The this reference is said to have escaped when it is made available beyond its current scope. Following are common ways by which the this reference can escape:
Returning
thisfrom a nonprivate, overridable method that is invoked from the constructor of a class whose object is being constructed (for more information, see MET05-J. Ensure that constructors do not call overridable methods).- Returning
thisfrom a nonprivate method of a mutable class, which allows the caller to manipulate the object's state indirectly. This situation commonly occurs in method-chaining implementations (see VNA04-J. Ensure that calls to chained methods are atomic for more information). - Passing
thisas an argument to an alien method invoked from the constructor of a class whose object is being constructed. - Using inner classes. An inner class implicitly holds a reference to the instance of its outer class unless the inner class is declared static.
- Publishing by assigning
thisto a public static variable from the constructor of a class whose object is being constructed. - Throwing an exception from a constructor. Doing so may cause code to be vulnerable to a finalizer attack (see OBJ11-J. Be wary of letting constructors throw exceptions for more information).
- Passing internal object state to an alien method, which enables the method to retrieve the
thisreference of the internal member object.
This rule describes the potential consequences of allowing the this reference to escape during object construction, including race conditions and improper initialization. For example, declaring a field final ordinarily ensures that all threads see the field in a fully initialized state; however, allowing the this reference to escape during object construction can expose the field to other threads in an uninitialized or partially initialized state. TSM03-J. Do not publish partially initialized objects, which describes the guarantees provided by various mechanisms for safe publication, relies on conformance to this rule. Consequently, programs must not allow the this reference to escape during object construction.
In general, it is important to detect cases in which the this reference can leak out beyond the scope of the current context. In particular, public variables and methods should be carefully scrutinized.
Noncompliant Code Example (Publish before Initialization)
This noncompliant code example publishes the this reference before initialization has concluded by storing it in a public static volatile class field. Consequently, other threads can obtain a partially initialized Publisher instance.
| Code Block | ||
|---|---|---|
| ||
{{this}}|http://java.sun.com/docs/books/jls/third_edition/html/expressions.html#15.8.3] \[[JLS 2005|AA. References#JLS 05]\]: {quote} When used as a primary expression, the keyword {{this}} denotes a value that is a reference to the object for which the instance method was invoked (§15.12), or to the object being constructed. The type of {{this}} is the class {{C}} within which the keyword {{this}} occurs. At run time, the class of the actual object referred to may be the class {{C}} or any subclass of {{C}}. {quote} The {{this}} reference is said to have escaped when it is made available beyond its current scope. Following are common ways by which the {{this}} reference can escape: * Returning {{this}} from a non-private, overridable method that is invoked from the constructor of a class whose object is being constructed. (For more information, see rule [MET05-J. Ensure that constructors do not call overridable methods].) {mc} subclasses! {mc} * Returning {{this}} from a nonprivate method of a mutable class, which allows the caller to manipulate the object's state indirectly. This commonly occurs in method-chaining implementations; see rule [VNA04-J. Ensure that calls to chained methods are atomic] for more information. * Passing {{this}} as an argument to an [_alien method_|BB. Glossary#alien method] invoked from the constructor of a class whose object is being constructed. * Using inner classes. An inner class implicitly holds a reference to the instance of its outer class unless the inner class is declared static. * Publishing by assigning {{this}} to a public static variable from the constructor of a class whose object is being constructed. * Throwing an exception from a constructor. Doing so may cause code to be vulnerable to a finalizer attack; see rule [OBJ11-J. Be wary of letting constructors throw exceptions] for more information. * Passing internal object state to an [_alien method_|BB. Glossary#alien method]. This enables the method to retrieve the {{this}} reference of the internal member object. This rule describes the potential consequences of allowing the {{this}} reference to escape during object construction, including race conditions and improper initialization. For example, declaring a field final ordinarily ensures that all threads see the field in a fully initialized state; however, allowing the {{this}} reference to escape during object construction can expose the field to other threads in an uninitialized or partially initialized state. Rule [TSM03-J. Do not publish partially initialized objects], which describes the guarantees provided by various mechanisms for safe publication, relies on conformance to this rule. Consequently, programs must not allow the {{this}} reference to escape during object construction. In general, it is important to detect cases in which the {{this}} reference can leak out beyond the scope of the current context. In particular, public variables and methods should be carefully scrutinized. h2. Noncompliant Code Example (Publish before Initialization) This noncompliant code example publishes the {{this}} reference before initialization has concluded by storing it in a public static volatile class field. Consequently, other threads can obtain a partially initialized {{Publisher}} instance. {code:bgColor=#FFcccc} final class Publisher { public static volatile Publisher published; int num; Publisher(int number) { published = this; // Initialization this.num = number; // ... } } {code} If an |
If an object's
...
initialization
...
(and
...
consequently,
...
its
...
construction)
...
depends
...
on
...
a
...
security
...
check
...
within
...
the
...
constructor,
...
the
...
security
...
check
...
can
...
be
...
bypassed
...
when
...
an
...
untrusted
...
caller
...
obtains
...
the
...
partially
...
initialized
...
instance (see OBJ11-J.
...
...
...
...
...
...
...
...
for
...
more
...
information).
Noncompliant Code Example (Nonvolatile Public Static Field)
This noncompliant code example publishes the this reference in the last statement of the constructor. It remains vulnerable because the published field has public accessibility and the programmer has failed to declare it as volatile.
| Code Block | ||
|---|---|---|
| ||
. h2. Noncompliant Code Example (Nonvolatile Public Static Field) This noncompliant code example publishes the {{this}} reference in the last statement of the constructor. It remains vulnerable because the {{published}} field has public accessibility and the programmer has failed to declare it as volatile. {code:bgColor=#FFcccc} final class Publisher { public static Publisher published; int num; Publisher(int number) { // Initialization this.num = number; // ... published = this; } } {code} |
Because
...
the
...
field
...
is
...
nonvolatile
...
and
...
nonfinal,
...
the
...
statements
...
within
...
the
...
constructor
...
can
...
be
...
reordered
...
by
...
the
...
compiler
...
in
...
such
...
a
...
way
...
that
...
the
...
this
...
reference
...
is
...
published
...
before
...
the
...
initialization
...
statements
...
have
...
executed.
...
Compliant
...
Solution
...
(Volatile
...
Field
...
and
...
Publish
...
after
...
Initialization)
...
This
...
compliant
...
solution
...
both
...
declares
...
the
...
published
...
field
...
volatile
...
and
...
reduces
...
its
...
accessibility
...
to
...
package-private
...
so
...
that
...
callers
...
outside
...
the
...
current
...
package
...
scope
...
cannot
...
obtain
...
the
...
this
...
reference.
| Code Block | ||||
|---|---|---|---|---|
| =
| |||
} final class Publisher { static volatile Publisher published; int num; Publisher(int number) { // Initialization this.num = number; // ... published = this; } } {code} |
The
...
constructor
...
publishes
...
the
...
this
...
reference
...
after
...
initialization
...
has
...
concluded.
...
However,
...
the
...
caller
...
that
...
instantiates
...
Publisher
...
must
...
ensure
...
that
...
it
...
cannot
...
see
...
the
...
default
...
value
...
of
...
the
...
num
...
field
...
before
...
it
...
is
...
initialized;
...
to
...
do
...
otherwise
...
would
...
violate TSM03-J.
...
...
...
...
...
...
...
.
...
Consequently,
...
the
...
field
...
that
...
holds
...
the
...
reference
...
to
...
Publisher
...
might
...
need
...
to
...
be
...
declared
...
volatile
...
in
...
the
...
caller.
...
Initialization
...
statements
...
may
...
be
...
reordered
...
when
...
the
...
published
...
field
...
is
...
not
...
declared
...
volatile.
...
The
...
Java
...
compiler,
...
however,
...
forbids
...
declaring
...
fields
...
as
...
both
...
volatile
...
and
...
final.
...
The
...
class
...
Publisher
...
must
...
also
...
be
...
final;
...
otherwise,
...
a
...
subclass
...
can
...
call
...
its
...
constructor
...
and
...
publish
...
the
...
this
...
reference
...
before
...
the
...
subclass's
...
initialization
...
has
...
concluded.
...
Compliant Solution (Public
...
Static
...
Factory
...
Method)
...
This
...
compliant
...
solution
...
eliminates
...
the
...
internal
...
member
...
field
...
and
...
provides
...
a
...
newInstance()
...
factory
...
method
...
that
...
creates
...
and
...
returns
...
a
...
Publisher instance:
| Code Block | ||
|---|---|---|
| ||
}} instance. {code:bgColor=#ccccff} final class Publisher { final int num; private Publisher(int number) { // Initialization this.num = number; } public static Publisher newInstance(int number) { Publisher published = new Publisher(number); return published; } } {code} |
This
...
approach
...
ensures
...
that
...
threads
...
cannot
...
see
...
an
...
inconsistent
...
Publisher
...
instance.
...
The
...
num
...
field
...
is
...
also
...
declared
...
final,
...
making
...
the
...
class
...
...
and
...
consequently
...
eliminating
...
the
...
possibility
...
of
...
obtaining
...
a
...
partially
...
initialized
...
object.
...
Noncompliant
...
Code
...
Example
...
(Handlers)
...
This
...
noncompliant
...
code
...
example
...
defines
...
the
...
ExceptionReporter
...
interface:
| Code Block |
|---|
{code} public interface ExceptionReporter { public void setExceptionReporter(ExceptionReporter er); public void report(Throwable exception); } {code} |
This
...
interface
...
is
...
implemented
...
by
...
the
...
DefaultExceptionReporter
...
class,
...
which
...
reports
...
exceptions
...
after
...
filtering
...
out
...
any
...
sensitive
...
information (see ERR00-J.
...
...
...
...
...
...
...
...
for
...
more
...
information).
...
The
...
DefaultExceptionReporter
...
constructor
...
prematurely
...
publishes
...
the
...
this
...
reference
...
before
...
construction
...
of
...
the
...
object
...
has
...
concluded.
...
This
...
occurs
...
in
...
the
...
last
...
statement
...
of
...
the
...
constructor
...
(
...
er.setExceptionReporter(this)
...
),
...
which
...
sets
...
the
...
exception
...
reporter.
...
Because
...
it
...
is
...
the
...
last
...
statement
...
of
...
the
...
constructor,
...
this
...
may
...
be
...
misconstrued
...
as
...
benign.
| Code Block | ||||
|---|---|---|---|---|
| =
| |||
} // Class DefaultExceptionReporter public class DefaultExceptionReporter implements ExceptionReporter { public DefaultExceptionReporter(ExceptionReporter er) { // Carry out initialization // Incorrectly publishes the "this" reference er.setExceptionReporter(this); } // Implementation of setExceptionReporter() and report() } {code} |
The MyExceptionReporter class subclasses DefaultExceptionReporter with the intent of adding a logging mechanism that logs critical messages before reporting an exception.
| Code Block | ||
|---|---|---|
| ||
The {{MyExceptionReporter}} class subclasses {{DefaultExceptionReporter}} with the intent of adding a logging mechanism that logs critical messages before reporting an exception. {code:bgColor=#FFcccc} // Class MyExceptionReporter derives from DefaultExceptionReporter public class MyExceptionReporter extends DefaultExceptionReporter { private final Logger logger; public MyExceptionReporter(ExceptionReporter er) { super(er); // Calls superclass's constructor // Obtain the default logger logger = Logger.getLogger("com.organization.Log"); } public void report(Throwable t) { logger.log(Level.FINEST,"Loggable exception occurred", t); } } {code} The {{MyExceptionReporter}} constructor invokes the {{DefaultExceptionReporter}} |
The MyExceptionReporter constructor invokes the DefaultExceptionReporter superclass's
...
constructor
...
(a
...
mandatory
...
first
...
step),
...
which
...
publishes
...
the
...
exception
...
reporter
...
before
...
the
...
initialization
...
of
...
the
...
subclass
...
has
...
concluded.
...
Note
...
that
...
the
...
subclass
...
initialization
...
consists
...
of
...
obtaining
...
an
...
instance
...
of
...
the
...
default
...
logger.
...
Publishing
...
the
...
exception
...
reporter
...
is
...
equivalent
...
to
...
setting
...
it
...
to
...
receive
...
and
...
handle
...
exceptions
...
from
...
that
...
point
...
on.
...
Logging
...
will
...
fail
...
when
...
an
...
exception
...
occurs
...
before
...
the
...
call
...
to
...
Logger.getLogger()
...
in
...
the
...
MyExceptionReporter
...
subclass
...
because
...
dereferencing
...
the
...
uninitialized
...
logger
...
field
...
generates
...
a
...
NullPointerException
...
,
...
which
...
could
...
itself
...
be
...
consumed
...
by
...
the
...
reporting
...
mechanism
...
without
...
being
...
logged.
...
This
...
erroneous
...
behavior
...
results
...
from
...
the
...
...
...
between
...
an
...
oncoming
...
exception
...
and
...
the
...
initialization
...
of
...
MyExceptionReporter
...
.
...
If
...
the
...
exception
...
arrives
...
too
...
soon,
...
it
...
will
...
find
...
the
...
MyExceptionReporter
...
object
...
in
...
an
...
inconsistent
...
state.
...
This
...
behavior
...
is
...
especially
...
counterintuitive
...
because
...
logger has been declared final,
...
so
...
observing
...
an
...
uninitialized
...
value
...
would
...
be
...
unexpected.
...
Premature
...
publication
...
of
...
an
...
event
...
listener
...
causes
...
a
...
similar
...
problem;
...
the
...
listener
...
can
...
receive
...
event
...
notifications
...
before
...
the
...
subclass's
...
initialization
...
has
...
finished.
Compliant Solution
Rather than publishing the this reference from the DefaultExceptionReporter constructor, this compliant solution adds a publishExceptionReporter() method to DefaultExceptionReporter to permit setting the exception reporter. This method can be invoked on a subclass instance after the subclass's initialization has concluded.
| Code Block | ||
|---|---|---|
| ||
h2. Compliant Solution Rather than publishing the {{this}} reference from the {{DefaultExceptionReporter}} constructor, this compliant solution adds a {{publishExceptionReporter()}} method to {{DefaultExceptionReporter}} to permit setting the exception reporter. This method can be invoked on a subclass instance after the subclass's initialization has concluded. {code:bgColor=#ccccff} public class DefaultExceptionReporter implements ExceptionReporter { public DefaultExceptionReporter(ExceptionReporter er) { // ... } // Should be called after subclass's initialization is over public void publishExceptionReporter() { setExceptionReporter(this); // Registers this exception reporter } // Implementation of setExceptionReporter() and report() } {code} The {{MyExceptionReporter}} subclass inherits the {{ |
The MyExceptionReporter subclass inherits the publishExceptionReporter()
...
method.
...
Callers
...
that
...
instantiate MyExceptionReporter can use the resulting instance to set the exception reporter after initialization is complete.
| Code Block | ||
|---|---|---|
| ||
{{MyExceptionReporter}} can use the resulting instance to set the exception reporter after initialization is complete. {code:bgColor=#ccccff} // Class MyExceptionReporter derives from DefaultExceptionReporter public class MyExceptionReporter extends DefaultExceptionReporter { private final Logger logger; public MyExceptionReporter(ExceptionReporter er) { super(er); // Calls superclass's constructor logger = Logger.getLogger("com.organization.Log"); } // Implementations of publishExceptionReporter(), // setExceptionReporter() and report() // are inherited } {code} |
This
...
approach
...
ensures
...
that
...
the
...
reporter
...
cannot
...
be
...
set
...
before
...
the
...
constructor
...
has
...
fully
...
initialized
...
the
...
subclass
...
and
...
enabled
...
logging.
...
Noncompliant Code Example (Inner
...
Class)
...
Inner
...
classes
...
maintain
...
a
...
copy
...
of
...
the
...
this
...
reference
...
of
...
the
...
outer
...
object.
...
Consequently,
...
the
...
this
...
reference
...
could
...
leak
...
outside
...
the
...
scope
...
...
...
].
...
This
...
noncompliant
...
code
...
example
...
uses
...
a
...
different
...
implementation
...
of
...
the
...
DefaultExceptionReporter
...
class.
...
The
...
constructor
...
uses
...
an
...
anonymous
...
inner
...
class
...
to
...
publish
...
an
...
exception
...
reporter.
| Code Block | ||||
|---|---|---|---|---|
| =
| |||
} public class DefaultExceptionReporter implements ExceptionReporter { public DefaultExceptionReporter(ExceptionReporter er) { er.setExceptionReporter(new DefaultExceptionReporterExceptionReporter(er) { public void report(Throwable t) { // report exception } public void setExceptionReporter(ExceptionReporter er) { // register ExceptionReporter } }); } // Default implementations of setExceptionReporter() and report() } {code} |
Other
...
threads
...
can
...
see
...
the
...
this
...
reference
...
of
...
the
...
outer
...
class
...
because
...
it
...
is
...
published
...
by
...
the
...
inner
...
class.
...
Furthermore,
...
the
...
issue
...
described
...
in
...
the
...
noncompliant
...
code
...
example
...
for
...
handlers
...
will
...
resurface
...
if
...
the
...
class
...
is
...
subclassed.
Compliant Solution
Use a private constructor and a public static factory method to safely publish the exception reporter from within the constructor [Goetz 2006a]:
| Code Block | ||
|---|---|---|
| ||
h2. Compliant Solution Use a private constructor and a public static factory method to safely publish the exception reporter from within the constructor \[[Goetz 2006a|AA. References#Goetz 06]\]. {code:bgColor=#ccccff} public class DefaultExceptionReporter implements ExceptionReporter { private final DefaultExceptionReporterExceptionReporter defaultER; private DefaultExceptionReporter(ExceptionReporter excr) { defaultER = new DefaultExceptionReporterExceptionReporter(excr) { public void report(Throwable t) { // report exceptionReport exception } public void setExceptionReporter(ExceptionReporter er) { // Register ExceptionReporter } }; } public static DefaultExceptionReporter newInstance( ExceptionReporter excr) { DefaultExceptionReporter der = new DefaultExceptionReporter(excr); excr.setExceptionReporter(der.defaultER); return der; } // Default implementations of setExceptionReporter() and report() } {code} |
Because
...
the
...
constructor
...
is
...
private,
...
untrusted
...
code
...
cannot
...
create
...
instances
...
of
...
the
...
class;
...
consequently,
...
the
...
this
...
reference
...
cannot
...
escape.
...
Using
...
a
...
public
...
static
...
factory
...
method
...
to
...
create
...
new
...
instances
...
also
...
protects
...
against
...
untrusted
...
manipulation
...
of
...
internal
...
object
...
state
...
and
...
publication
...
of
...
partially
...
initialized
...
objects (see TSM03-J.
...
...
...
...
...
...
...
for
...
additional
...
information
...
).
Noncompliant Code Example (Thread)
...
This
...
noncompliant
...
code
...
example
...
starts
...
a
...
thread
...
inside
...
the constructor:
| Code Block | ||
|---|---|---|
| ||
constructor. {code:bgColor=#FFcccc} final class ThreadStarter implements Runnable { public ThreadStarter() { Thread thread = new Thread(this); thread.start(); } @Override public void run() { // ... } } {code} |
The
...
new
...
thread
...
can
...
access
...
the
...
this
...
reference
...
of
...
the
...
current
...
object
...
[
...
...
...
]
...
,
...
...
...
]. Notably, the Thread()
...
constructor
...
is
...
...
to
...
the
...
ThreadStarter
...
class.
...
Compliant Solution (Thread)
...
This
...
compliant
...
solution
...
creates
...
and
...
starts
...
the
...
thread
...
in
...
a
...
method
...
rather
...
than
...
in
...
the constructor:
| Code Block | ||
|---|---|---|
| ||
constructor. {code:bgColor=#ccccff} final class ThreadStarter implements Runnable { public void startThread() { Thread thread = new Thread(this); thread.start(); } @Override public void run() { // ... } } {code} h2. Exceptions *TSM01 |
Exceptions
TSM01-J-EX0:
...
It
...
is
...
safe
...
to
...
create
...
a
...
thread
...
in
...
the
...
constructor,
...
provided
...
the
...
thread
...
is
...
not
...
started
...
until
...
after
...
object
...
construction
...
is
...
complete,
...
because
...
a
...
call
...
to
...
start()
...
on
...
a
...
thread
...
...
...
any
...
actions
...
in
...
the
...
started
...
thread
...
[JLS 2015].
Even though this code example creates a thread that references this in the constructor, the thread is started only when its start() method is called from the startThread() method [Goetz 2002], [Goetz 2006a].
| Code Block | ||
|---|---|---|
| ||
[JLS 2005|AA. References#JLS 05]\]. Even though this code example creates a thread that references {{this}} in the constructor, the thread is started only when its {{start()}} method is called from the {{startThread()}} method \[[Goetz 2002|AA. References#Goetz 02]\], \[[Goetz 2006a|AA. References#Goetz 06]\]. {code:bgColor=#ccccff} final class ThreadStarter implements Runnable { Thread thread; public ThreadStarter() { thread = new Thread(this); } public void startThread() { thread.start(); } @Override public void run() { // ... } } {code} * |
TSM01-J-EX1:
...
Use
...
of
...
the
...
ObjectPreserver
...
pattern
...
...
...
]
...
described
...
in
...
...
...
...
...
...
...
...
...
...
is
...
safe
...
and
...
is
...
permitted.
...
Risk
...
Assessment
...
Allowing
...
the
...
this
...
reference
...
to
...
escape
...
can
...
result
...
in
...
improper
...
initialization
...
and
...
runtime
...
exceptions.
Rule | Severity | Likelihood | Remediation Cost | Priority | Level |
|---|---|---|---|---|---|
TSM01-J | Medium | Probable | High | P4 | L3 |
Automated Detection
| Tool | Version | Checker | Description | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Parasoft Jtest |
| CERT.TSM01.CTRE | Do not let "this" reference escape during construction |
Bibliography
Section 3.2, "Publication and Escape" | |
Chapter 5, "Creational Patterns, Singleton" | |
| [JLS 2015] | §15.8.3, "this" |
Issue Tracking
| Tasklist | ||||
|---|---|---|---|---|
| ||||
||Completed||Priority||Locked||CreatedDate||CompletedDate||Assignee||Name| || Rule || Severity || Likelihood || Remediation Cost || Priority || Level || | TSM01-J | medium | probable | high | {color:green}{*}P4{*}{color} | {color:green}{*}L3{*}{color} | h2. Bibliography | \[[JLS 2005|AA. References#JLS 05]\] | Keyword {{this}} | | \[[Goetz 2002|AA. References#Goetz 02]\] | | | \[[Goetz 2006a|AA. References#Goetz 06]\] | Section 3.2, Publication and Escape | | \[[Grand 2002|AA. References#Grand 02]\] | Chapter 5, Creational Patterns, Singleton | h2. Issue Tracking {tasklist:Review List} ||Completed||Priority||Locked||CreatedDate||CompletedDate||Assignee||Name|| |T|M|F|1270219843973|1270221864972|svoboda|"*Inner classes* implicitly hold a reference to the instance of the outer class, unless the inner class is declared as static." => Change inner classes to "An inner class implicitly holds ... "| |T|M|F|12702201298711270219843973|12707559347901270221864972|rcssvoboda|"Note*Inner thatclasses* thisimplicitly codehold alsoa violates CON32-J. Protect accessible mutable static fields from untrusted code" => Not sure if I agree becausereference to the class is package-private and inaccessible to untrusted code| |T|M|F|1270733657099|1271021912028|rcs_mgr|"A Runnable object's constructor may construct a Thread object around itself, as long as the thread is not actually started in the Runnable object's constructor." => I still think this info is redundant.| {tasklist} ---- [!The CERT Oracle Secure Coding Standard for Java^button_arrow_left.png!|TSM00-J. Do not override thread-safe methods with methods that are not thread-safe] [!The CERT Oracle Secure Coding Standard for Java^button_arrow_up.png!|11. Thread-Safety Miscellaneous (TSM)] [!The CERT Oracle Secure Coding Standard for Java^button_arrow_right.png!|TSM02-J. Do not use background threads during class initialization] instance of the outer class, unless the inner class is declared as static." => Change inner classes to "An inner class implicitly holds ... "| |T|M|F|1270220129871|1270755934790|rcs|"Note that this code also violates CON32-J. Protect accessible mutable static fields from untrusted code" => Not sure if I agree because the class is package-private and inaccessible to untrusted code| |T|M|F|1270733657099|1271021912028|rcs_mgr|"A Runnable object's constructor may construct a Thread object around itself, as long as the thread is not actually started in the Runnable object's constructor." => I still think this info is redundant.| |
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