Java and property overload
0
I'm stucked on this issue using eclipse 2018-12 (4.10) / Java 11 on debian 9
Let's state I've a base class
class A
private typeA prop;
TypeA getProp()
return this.prop;
and a derived one
class B extends A{
private typeB prop;
TypeB getProp()
return this.prop;
I'm expecting that prop in class B hides the prop in class A, but in eclipse I've got an error Message in class B for the getProp method :
The return type is incompatible with A.getProp()
any idea ?
java inheritance properties field
asked Nov 14 '18 at 18:05
EmmanuelEmmanuel
4771931
|
show 5 more comments
0
I'm stucked on this issue using eclipse 2018-12 (4.10) / Java 11 on debian 9
Let's state I've a base class
class A
private typeA prop;
TypeA getProp()
return this.prop;
and a derived one
class B extends A{
private typeB prop;
TypeB getProp()
return this.prop;
I'm expecting that prop in class B hides the prop in class A, but in eclipse I've got an error Message in class B for the getProp method :
The return type is incompatible with A.getProp()
any idea ?
java inheritance properties field
asked Nov 14 '18 at 18:05
EmmanuelEmmanuel
4771931
You overridedgetProp; name them differently.
– rgettman
Nov 14 '18 at 18:07
Any method is not overridden if it just differs by return type.
– CS_noob
Nov 14 '18 at 18:08
Besides your issue your code does not compile, you have a method that returnsTypeBand you're trying to return a variable of typetypeB. Also you're missing semicolons.
– Mark
Nov 14 '18 at 18:08
I just don't want to name the differently .. why getProp() in class B does not overload getProp in class A ?
– Emmanuel
Nov 14 '18 at 18:08
3
That would completely break polymorphism, and the Liskov principle. An A has a getProp() that returns a TypeA. B extends A. So any instance of B is an instance of A. So calling getProp() on a B instance must return a TypeA: that's the contract of the class A. Just take this code, that is supposed to work:A a = new B(); TypeA typeA = a.getProp();. Your code would make that impossible.
– JB Nizet
Nov 14 '18 at 18:09
|
show 5 more comments
0
0
0
I'm stucked on this issue using eclipse 2018-12 (4.10) / Java 11 on debian 9
Let's state I've a base class
class A
private typeA prop;
TypeA getProp()
return this.prop;
and a derived one
class B extends A{
private typeB prop;
TypeB getProp()
return this.prop;
I'm expecting that prop in class B hides the prop in class A, but in eclipse I've got an error Message in class B for the getProp method :
The return type is incompatible with A.getProp()
any idea ?
java inheritance properties field
asked Nov 14 '18 at 18:05
EmmanuelEmmanuel
4771931
I'm stucked on this issue using eclipse 2018-12 (4.10) / Java 11 on debian 9
Let's state I've a base class
class A
private typeA prop;
TypeA getProp()
return this.prop;
and a derived one
class B extends A{
private typeB prop;
TypeB getProp()
return this.prop;
I'm expecting that prop in class B hides the prop in class A, but in eclipse I've got an error Message in class B for the getProp method :
The return type is incompatible with A.getProp()
any idea ?
java inheritance properties field
java inheritance properties field
asked Nov 14 '18 at 18:05
EmmanuelEmmanuel
4771931
asked Nov 14 '18 at 18:05
EmmanuelEmmanuel
4771931
edited Nov 14 '18 at 18:09
Emmanuel
asked Nov 14 '18 at 18:05
EmmanuelEmmanuel
4771931
asked Nov 14 '18 at 18:05
EmmanuelEmmanuel
4771931
asked Nov 14 '18 at 18:05
EmmanuelEmmanuel
4771931
4771931
You overridedgetProp; name them differently.
– rgettman
Nov 14 '18 at 18:07
Any method is not overridden if it just differs by return type.
– CS_noob
Nov 14 '18 at 18:08
Besides your issue your code does not compile, you have a method that returnsTypeBand you're trying to return a variable of typetypeB. Also you're missing semicolons.
– Mark
Nov 14 '18 at 18:08
I just don't want to name the differently .. why getProp() in class B does not overload getProp in class A ?
– Emmanuel
Nov 14 '18 at 18:08
3
That would completely break polymorphism, and the Liskov principle. An A has a getProp() that returns a TypeA. B extends A. So any instance of B is an instance of A. So calling getProp() on a B instance must return a TypeA: that's the contract of the class A. Just take this code, that is supposed to work:A a = new B(); TypeA typeA = a.getProp();. Your code would make that impossible.
– JB Nizet
Nov 14 '18 at 18:09
|
show 5 more comments
You overridedgetProp; name them differently.
– rgettman
Nov 14 '18 at 18:07
Any method is not overridden if it just differs by return type.
– CS_noob
Nov 14 '18 at 18:08
Besides your issue your code does not compile, you have a method that returnsTypeBand you're trying to return a variable of typetypeB. Also you're missing semicolons.
– Mark
Nov 14 '18 at 18:08
I just don't want to name the differently .. why getProp() in class B does not overload getProp in class A ?
– Emmanuel
Nov 14 '18 at 18:08
3
That would completely break polymorphism, and the Liskov principle. An A has a getProp() that returns a TypeA. B extends A. So any instance of B is an instance of A. So calling getProp() on a B instance must return a TypeA: that's the contract of the class A. Just take this code, that is supposed to work:A a = new B(); TypeA typeA = a.getProp();. Your code would make that impossible.
– JB Nizet
Nov 14 '18 at 18:09
You overrided
getProp; name them differently.– rgettman
Nov 14 '18 at 18:07
You overrided
getProp; name them differently.– rgettman
Nov 14 '18 at 18:07
Any method is not overridden if it just differs by return type.
– CS_noob
Nov 14 '18 at 18:08
Any method is not overridden if it just differs by return type.
– CS_noob
Nov 14 '18 at 18:08
Besides your issue your code does not compile, you have a method that returns
TypeB and you're trying to return a variable of type typeB. Also you're missing semicolons.– Mark
Nov 14 '18 at 18:08
Besides your issue your code does not compile, you have a method that returns
TypeB and you're trying to return a variable of type typeB. Also you're missing semicolons.– Mark
Nov 14 '18 at 18:08
I just don't want to name the differently .. why getProp() in class B does not overload getProp in class A ?
– Emmanuel
Nov 14 '18 at 18:08
I just don't want to name the differently .. why getProp() in class B does not overload getProp in class A ?
– Emmanuel
Nov 14 '18 at 18:08
3
3
That would completely break polymorphism, and the Liskov principle. An A has a getProp() that returns a TypeA. B extends A. So any instance of B is an instance of A. So calling getProp() on a B instance must return a TypeA: that's the contract of the class A. Just take this code, that is supposed to work:
A a = new B(); TypeA typeA = a.getProp();. Your code would make that impossible.– JB Nizet
Nov 14 '18 at 18:09
That would completely break polymorphism, and the Liskov principle. An A has a getProp() that returns a TypeA. B extends A. So any instance of B is an instance of A. So calling getProp() on a B instance must return a TypeA: that's the contract of the class A. Just take this code, that is supposed to work:
A a = new B(); TypeA typeA = a.getProp();. Your code would make that impossible.– JB Nizet
Nov 14 '18 at 18:09
|
show 5 more comments
2 Answers
2
active
oldest
votes
0
Solved using JB Nizet comment through TypeA inheritance -> TypeB
answered Nov 14 '18 at 18:19
EmmanuelEmmanuel
4771931
add a comment |
0
you can try using interfaces like this:
interface Type
// ...
class TypeA implements Type
// ...
class TypeB implements Type
// ...
class A
private TypeA prop;
Type getProp()
return this.prop;
class B extends A
private TypeB prop;
Type getProp()
return this.prop;
answered Nov 14 '18 at 18:22
elbraulioelbraulio
746213
add a comment |
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2 Answers
2
active
oldest
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2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
0
Solved using JB Nizet comment through TypeA inheritance -> TypeB
answered Nov 14 '18 at 18:19
EmmanuelEmmanuel
4771931
add a comment |
0
Solved using JB Nizet comment through TypeA inheritance -> TypeB
answered Nov 14 '18 at 18:19
EmmanuelEmmanuel
4771931
add a comment |
0
0
0
Solved using JB Nizet comment through TypeA inheritance -> TypeB
answered Nov 14 '18 at 18:19
EmmanuelEmmanuel
4771931
Solved using JB Nizet comment through TypeA inheritance -> TypeB
answered Nov 14 '18 at 18:19
EmmanuelEmmanuel
4771931
answered Nov 14 '18 at 18:19
EmmanuelEmmanuel
4771931
answered Nov 14 '18 at 18:19
EmmanuelEmmanuel
4771931
answered Nov 14 '18 at 18:19
EmmanuelEmmanuel
4771931
4771931
add a comment |
add a comment |
0
you can try using interfaces like this:
interface Type
// ...
class TypeA implements Type
// ...
class TypeB implements Type
// ...
class A
private TypeA prop;
Type getProp()
return this.prop;
class B extends A
private TypeB prop;
Type getProp()
return this.prop;
answered Nov 14 '18 at 18:22
elbraulioelbraulio
746213
add a comment |
0
you can try using interfaces like this:
interface Type
// ...
class TypeA implements Type
// ...
class TypeB implements Type
// ...
class A
private TypeA prop;
Type getProp()
return this.prop;
class B extends A
private TypeB prop;
Type getProp()
return this.prop;
answered Nov 14 '18 at 18:22
elbraulioelbraulio
746213
add a comment |
0
0
0
you can try using interfaces like this:
interface Type
// ...
class TypeA implements Type
// ...
class TypeB implements Type
// ...
class A
private TypeA prop;
Type getProp()
return this.prop;
class B extends A
private TypeB prop;
Type getProp()
return this.prop;
answered Nov 14 '18 at 18:22
elbraulioelbraulio
746213
you can try using interfaces like this:
interface Type
// ...
class TypeA implements Type
// ...
class TypeB implements Type
// ...
class A
private TypeA prop;
Type getProp()
return this.prop;
class B extends A
private TypeB prop;
Type getProp()
return this.prop;
answered Nov 14 '18 at 18:22
elbraulioelbraulio
746213
answered Nov 14 '18 at 18:22
elbraulioelbraulio
746213
answered Nov 14 '18 at 18:22
elbraulioelbraulio
746213
answered Nov 14 '18 at 18:22
elbraulioelbraulio
746213
746213
add a comment |
add a comment |
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You overrided
getProp; name them differently.– rgettman
Nov 14 '18 at 18:07
Any method is not overridden if it just differs by return type.
– CS_noob
Nov 14 '18 at 18:08
Besides your issue your code does not compile, you have a method that returns
TypeBand you're trying to return a variable of typetypeB. Also you're missing semicolons.– Mark
Nov 14 '18 at 18:08
I just don't want to name the differently .. why getProp() in class B does not overload getProp in class A ?
– Emmanuel
Nov 14 '18 at 18:08
3
That would completely break polymorphism, and the Liskov principle. An A has a getProp() that returns a TypeA. B extends A. So any instance of B is an instance of A. So calling getProp() on a B instance must return a TypeA: that's the contract of the class A. Just take this code, that is supposed to work:
A a = new B(); TypeA typeA = a.getProp();. Your code would make that impossible.– JB Nizet
Nov 14 '18 at 18:09