Java 9 replace Class.newInstance
Class.newInstance was deprecated in Java 9:
clazz.newInstance()
can be replaced by
clazz.getDeclaredConstructor().newInstance()
The problem is that getDeclaredConstructor returns any constructor without regarding the access level.
If I want to replace all occurrences in my code (on different packages/access level) should I use getConstructor to get the public constructor?
the Constructor object of the public constructor that matches the specified parameterTypes
Or can't I bulk replace all occurrences because it needs to be per case (if a public constructor exists and/or if I have the right access level for the class)?
EDIT
getDeclaredConstructor:
return getConstructor0(parameterTypes, Member.DECLARED);
getConstructor:
return getConstructor0(parameterTypes, Member.PUBLIC);
java reflection constructor java-9
edited Nov 13 at 14:33
Holger
162k23229435
asked Nov 12 at 6:44
user7294900
20.4k103258
|
show 1 more comment
Class.newInstance was deprecated in Java 9:
clazz.newInstance()
can be replaced by
clazz.getDeclaredConstructor().newInstance()
The problem is that getDeclaredConstructor returns any constructor without regarding the access level.
If I want to replace all occurrences in my code (on different packages/access level) should I use getConstructor to get the public constructor?
the Constructor object of the public constructor that matches the specified parameterTypes
Or can't I bulk replace all occurrences because it needs to be per case (if a public constructor exists and/or if I have the right access level for the class)?
EDIT
getDeclaredConstructor:
return getConstructor0(parameterTypes, Member.DECLARED);
getConstructor:
return getConstructor0(parameterTypes, Member.PUBLIC);
java reflection constructor java-9
edited Nov 13 at 14:33
Holger
162k23229435
asked Nov 12 at 6:44
user7294900
20.4k103258
1
If you need to access constructor at different levels, getDeclaredConstructor(s) is the only way out. Can't you usegetDeclaredConstructors()(notgetDeclaredConstructor()) to get all constructors and replace one depending on your logic?
– Sukhpal Singh
Nov 12 at 7:02
5
As the deprecation message says, the equivalent code toclazz.newInstance()isclazz.getDeclaredConstructor().newInstance(). I would assume this means that anywhere you're successfully usingclazz.newInstance()can be replaced with the recommended code. If you replaceclazz.newInstance()withclazz.getConstructor().newInstance()you're changing the semantics of the code.
– Slaw
Nov 12 at 7:04
2
I haven’t tried, but I wouldn’t expectclazz.newInstance()to work either if the zero-arg constructor isn’t public — does it?? So what would you be losing in practice by usingclazz.getDeclaredConstructor().newInstance()instead?
– Ole V.V.
Nov 12 at 7:22
2
@OleV.V. Yes,Class.newInstance()works with non-public constructors. But it requires you to have the proper access else it throws anIllegalAccessException(from some quick, non-exhaustive testing).
– Slaw
Nov 12 at 7:28
5
Related (on the reasons why it was deprecated): stackoverflow.com/questions/195321/…
– Hulk
Nov 12 at 8:09
|
show 1 more comment
Class.newInstance was deprecated in Java 9:
clazz.newInstance()
can be replaced by
clazz.getDeclaredConstructor().newInstance()
The problem is that getDeclaredConstructor returns any constructor without regarding the access level.
If I want to replace all occurrences in my code (on different packages/access level) should I use getConstructor to get the public constructor?
the Constructor object of the public constructor that matches the specified parameterTypes
Or can't I bulk replace all occurrences because it needs to be per case (if a public constructor exists and/or if I have the right access level for the class)?
EDIT
getDeclaredConstructor:
return getConstructor0(parameterTypes, Member.DECLARED);
getConstructor:
return getConstructor0(parameterTypes, Member.PUBLIC);
java reflection constructor java-9
edited Nov 13 at 14:33
Holger
162k23229435
asked Nov 12 at 6:44
user7294900
20.4k103258
Class.newInstance was deprecated in Java 9:
clazz.newInstance()
can be replaced by
clazz.getDeclaredConstructor().newInstance()
The problem is that getDeclaredConstructor returns any constructor without regarding the access level.
If I want to replace all occurrences in my code (on different packages/access level) should I use getConstructor to get the public constructor?
the Constructor object of the public constructor that matches the specified parameterTypes
Or can't I bulk replace all occurrences because it needs to be per case (if a public constructor exists and/or if I have the right access level for the class)?
EDIT
getDeclaredConstructor:
return getConstructor0(parameterTypes, Member.DECLARED);
getConstructor:
return getConstructor0(parameterTypes, Member.PUBLIC);
java reflection constructor java-9
java reflection constructor java-9
edited Nov 13 at 14:33
Holger
162k23229435
asked Nov 12 at 6:44
user7294900
20.4k103258
edited Nov 13 at 14:33
Holger
162k23229435
asked Nov 12 at 6:44
user7294900
20.4k103258
edited Nov 13 at 14:33
Holger
162k23229435
edited Nov 13 at 14:33
Holger
162k23229435
edited Nov 13 at 14:33
Holger
162k23229435
162k23229435
asked Nov 12 at 6:44
user7294900
20.4k103258
asked Nov 12 at 6:44
user7294900
20.4k103258
asked Nov 12 at 6:44
user7294900
20.4k103258
20.4k103258
1
If you need to access constructor at different levels, getDeclaredConstructor(s) is the only way out. Can't you usegetDeclaredConstructors()(notgetDeclaredConstructor()) to get all constructors and replace one depending on your logic?
– Sukhpal Singh
Nov 12 at 7:02
5
As the deprecation message says, the equivalent code toclazz.newInstance()isclazz.getDeclaredConstructor().newInstance(). I would assume this means that anywhere you're successfully usingclazz.newInstance()can be replaced with the recommended code. If you replaceclazz.newInstance()withclazz.getConstructor().newInstance()you're changing the semantics of the code.
– Slaw
Nov 12 at 7:04
2
I haven’t tried, but I wouldn’t expectclazz.newInstance()to work either if the zero-arg constructor isn’t public — does it?? So what would you be losing in practice by usingclazz.getDeclaredConstructor().newInstance()instead?
– Ole V.V.
Nov 12 at 7:22
2
@OleV.V. Yes,Class.newInstance()works with non-public constructors. But it requires you to have the proper access else it throws anIllegalAccessException(from some quick, non-exhaustive testing).
– Slaw
Nov 12 at 7:28
5
Related (on the reasons why it was deprecated): stackoverflow.com/questions/195321/…
– Hulk
Nov 12 at 8:09
|
show 1 more comment
1
If you need to access constructor at different levels, getDeclaredConstructor(s) is the only way out. Can't you usegetDeclaredConstructors()(notgetDeclaredConstructor()) to get all constructors and replace one depending on your logic?
– Sukhpal Singh
Nov 12 at 7:02
5
As the deprecation message says, the equivalent code toclazz.newInstance()isclazz.getDeclaredConstructor().newInstance(). I would assume this means that anywhere you're successfully usingclazz.newInstance()can be replaced with the recommended code. If you replaceclazz.newInstance()withclazz.getConstructor().newInstance()you're changing the semantics of the code.
– Slaw
Nov 12 at 7:04
2
I haven’t tried, but I wouldn’t expectclazz.newInstance()to work either if the zero-arg constructor isn’t public — does it?? So what would you be losing in practice by usingclazz.getDeclaredConstructor().newInstance()instead?
– Ole V.V.
Nov 12 at 7:22
2
@OleV.V. Yes,Class.newInstance()works with non-public constructors. But it requires you to have the proper access else it throws anIllegalAccessException(from some quick, non-exhaustive testing).
– Slaw
Nov 12 at 7:28
5
Related (on the reasons why it was deprecated): stackoverflow.com/questions/195321/…
– Hulk
Nov 12 at 8:09
1
1
If you need to access constructor at different levels, getDeclaredConstructor(s) is the only way out. Can't you use
getDeclaredConstructors() (not getDeclaredConstructor()) to get all constructors and replace one depending on your logic?– Sukhpal Singh
Nov 12 at 7:02
If you need to access constructor at different levels, getDeclaredConstructor(s) is the only way out. Can't you use
getDeclaredConstructors() (not getDeclaredConstructor()) to get all constructors and replace one depending on your logic?– Sukhpal Singh
Nov 12 at 7:02
5
5
As the deprecation message says, the equivalent code to
clazz.newInstance() is clazz.getDeclaredConstructor().newInstance(). I would assume this means that anywhere you're successfully using clazz.newInstance() can be replaced with the recommended code. If you replace clazz.newInstance() with clazz.getConstructor().newInstance() you're changing the semantics of the code.– Slaw
Nov 12 at 7:04
As the deprecation message says, the equivalent code to
clazz.newInstance() is clazz.getDeclaredConstructor().newInstance(). I would assume this means that anywhere you're successfully using clazz.newInstance() can be replaced with the recommended code. If you replace clazz.newInstance() with clazz.getConstructor().newInstance() you're changing the semantics of the code.– Slaw
Nov 12 at 7:04
2
2
I haven’t tried, but I wouldn’t expect
clazz.newInstance() to work either if the zero-arg constructor isn’t public — does it?? So what would you be losing in practice by using clazz.getDeclaredConstructor().newInstance() instead?– Ole V.V.
Nov 12 at 7:22
I haven’t tried, but I wouldn’t expect
clazz.newInstance() to work either if the zero-arg constructor isn’t public — does it?? So what would you be losing in practice by using clazz.getDeclaredConstructor().newInstance() instead?– Ole V.V.
Nov 12 at 7:22
2
2
@OleV.V. Yes,
Class.newInstance() works with non-public constructors. But it requires you to have the proper access else it throws an IllegalAccessException (from some quick, non-exhaustive testing).– Slaw
Nov 12 at 7:28
@OleV.V. Yes,
Class.newInstance() works with non-public constructors. But it requires you to have the proper access else it throws an IllegalAccessException (from some quick, non-exhaustive testing).– Slaw
Nov 12 at 7:28
5
5
Related (on the reasons why it was deprecated): stackoverflow.com/questions/195321/…
– Hulk
Nov 12 at 8:09
Related (on the reasons why it was deprecated): stackoverflow.com/questions/195321/…
– Hulk
Nov 12 at 8:09
|
show 1 more comment
1 Answer
1
active
oldest
votes
Class.newInstance() invokes the zero-argument constructor, whether it is public or not. It performs a runtime check of the caller's access to that constructor.
Calling getDeclaredConstructor() returns that same constructor. Calling getDeclaredConstructor().newInstance() performs the same runtime checks. Except for the different handling of exceptions, it does the same thing.
No, don't change it to getConstructor(). That would cause a NoSuchMethodException for non-public constructors.
answered Nov 12 at 15:22
Boann
36.7k1287121
Thank you, so any exceptions thrown will only be a valid initialization failures?
– user7294900
Nov 12 at 17:03
@user7294900 Yes.
– Boann
Nov 12 at 22:22
add a comment |
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Class.newInstance() invokes the zero-argument constructor, whether it is public or not. It performs a runtime check of the caller's access to that constructor.
Calling getDeclaredConstructor() returns that same constructor. Calling getDeclaredConstructor().newInstance() performs the same runtime checks. Except for the different handling of exceptions, it does the same thing.
No, don't change it to getConstructor(). That would cause a NoSuchMethodException for non-public constructors.
answered Nov 12 at 15:22
Boann
36.7k1287121
Thank you, so any exceptions thrown will only be a valid initialization failures?
– user7294900
Nov 12 at 17:03
@user7294900 Yes.
– Boann
Nov 12 at 22:22
add a comment |
Class.newInstance() invokes the zero-argument constructor, whether it is public or not. It performs a runtime check of the caller's access to that constructor.
Calling getDeclaredConstructor() returns that same constructor. Calling getDeclaredConstructor().newInstance() performs the same runtime checks. Except for the different handling of exceptions, it does the same thing.
No, don't change it to getConstructor(). That would cause a NoSuchMethodException for non-public constructors.
answered Nov 12 at 15:22
Boann
36.7k1287121
Thank you, so any exceptions thrown will only be a valid initialization failures?
– user7294900
Nov 12 at 17:03
@user7294900 Yes.
– Boann
Nov 12 at 22:22
add a comment |
Class.newInstance() invokes the zero-argument constructor, whether it is public or not. It performs a runtime check of the caller's access to that constructor.
Calling getDeclaredConstructor() returns that same constructor. Calling getDeclaredConstructor().newInstance() performs the same runtime checks. Except for the different handling of exceptions, it does the same thing.
No, don't change it to getConstructor(). That would cause a NoSuchMethodException for non-public constructors.
answered Nov 12 at 15:22
Boann
36.7k1287121
Class.newInstance() invokes the zero-argument constructor, whether it is public or not. It performs a runtime check of the caller's access to that constructor.
Calling getDeclaredConstructor() returns that same constructor. Calling getDeclaredConstructor().newInstance() performs the same runtime checks. Except for the different handling of exceptions, it does the same thing.
No, don't change it to getConstructor(). That would cause a NoSuchMethodException for non-public constructors.
answered Nov 12 at 15:22
Boann
36.7k1287121
answered Nov 12 at 15:22
Boann
36.7k1287121
answered Nov 12 at 15:22
Boann
36.7k1287121
answered Nov 12 at 15:22
Boann
36.7k1287121
36.7k1287121
Thank you, so any exceptions thrown will only be a valid initialization failures?
– user7294900
Nov 12 at 17:03
@user7294900 Yes.
– Boann
Nov 12 at 22:22
add a comment |
Thank you, so any exceptions thrown will only be a valid initialization failures?
– user7294900
Nov 12 at 17:03
@user7294900 Yes.
– Boann
Nov 12 at 22:22
Thank you, so any exceptions thrown will only be a valid initialization failures?
– user7294900
Nov 12 at 17:03
Thank you, so any exceptions thrown will only be a valid initialization failures?
– user7294900
Nov 12 at 17:03
@user7294900 Yes.
– Boann
Nov 12 at 22:22
@user7294900 Yes.
– Boann
Nov 12 at 22:22
add a comment |
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1
If you need to access constructor at different levels, getDeclaredConstructor(s) is the only way out. Can't you use
getDeclaredConstructors()(notgetDeclaredConstructor()) to get all constructors and replace one depending on your logic?– Sukhpal Singh
Nov 12 at 7:02
5
As the deprecation message says, the equivalent code to
clazz.newInstance()isclazz.getDeclaredConstructor().newInstance(). I would assume this means that anywhere you're successfully usingclazz.newInstance()can be replaced with the recommended code. If you replaceclazz.newInstance()withclazz.getConstructor().newInstance()you're changing the semantics of the code.– Slaw
Nov 12 at 7:04
2
I haven’t tried, but I wouldn’t expect
clazz.newInstance()to work either if the zero-arg constructor isn’t public — does it?? So what would you be losing in practice by usingclazz.getDeclaredConstructor().newInstance()instead?– Ole V.V.
Nov 12 at 7:22
2
@OleV.V. Yes,
Class.newInstance()works with non-public constructors. But it requires you to have the proper access else it throws anIllegalAccessException(from some quick, non-exhaustive testing).– Slaw
Nov 12 at 7:28
5
Related (on the reasons why it was deprecated): stackoverflow.com/questions/195321/…
– Hulk
Nov 12 at 8:09