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why only clone and finalize are protected method in object calss?
I understand the purpose of making the clone and finalize method as protected, I wanted to understand why hashcode() and equals method are not declared as protected
java object equals hashcode protected
asked Nov 22 '18 at 10:58
VigneshVignesh
165
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I understand the purpose of making the clone and finalize method as protected, I wanted to understand why hashcode() and equals method are not declared as protected
java object equals hashcode protected
asked Nov 22 '18 at 10:58
VigneshVignesh
165
Simply put, because you would like to use these outside of the class
– Ivan Kaloyanov
Nov 22 '18 at 11:01
add a comment |
I understand the purpose of making the clone and finalize method as protected, I wanted to understand why hashcode() and equals method are not declared as protected
java object equals hashcode protected
asked Nov 22 '18 at 10:58
VigneshVignesh
165
I understand the purpose of making the clone and finalize method as protected, I wanted to understand why hashcode() and equals method are not declared as protected
java object equals hashcode protected
java object equals hashcode protected
asked Nov 22 '18 at 10:58
VigneshVignesh
165
asked Nov 22 '18 at 10:58
VigneshVignesh
165
asked Nov 22 '18 at 10:58
VigneshVignesh
165
asked Nov 22 '18 at 10:58
VigneshVignesh
165
asked Nov 22 '18 at 10:58
VigneshVignesh
165
165
Simply put, because you would like to use these outside of the class
– Ivan Kaloyanov
Nov 22 '18 at 11:01
add a comment |
Simply put, because you would like to use these outside of the class
– Ivan Kaloyanov
Nov 22 '18 at 11:01
Simply put, because you would like to use these outside of the class
– Ivan Kaloyanov
Nov 22 '18 at 11:01
Simply put, because you would like to use these outside of the class
– Ivan Kaloyanov
Nov 22 '18 at 11:01
add a comment |
2 Answers
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Because you want to call hashcode and equals methods from the outside of that given class.
protected allows access only from the same package and extending classes.
answered Nov 22 '18 at 11:01
AntoniossssAntoniossss
16.1k12354
Hi @antoniossss, thanks for response, but Object class is root package for all the classes, so I believe it should be available to all the classes. one more reason why clone and finalize methods are protected is to make overriding it with either protected or public visibility. so why not hashcode and equals
– Vignesh
Nov 23 '18 at 6:45
You are wrong.protectedmethods of classa.b.Classare visible in packagea.bbut not ina.b.z
– Antoniossss
Nov 23 '18 at 8:13
add a comment |
You "understand the purpose of making the clone and finalize method as protected". But what is the purpose actually?
Calling Object.clone will throw an exception if the method isn't overridden and if Cloneable isn't implemented. Thus this method isn't ready to use.
Object.finalize is according to JavaDoc "called by the garbage collector". Thus it is for internal usage only.
In contrast to these both methods are Object.equals and Object.hashCode ready to use and not for internal usage.
The JavaDoc of Object.hashCode says:
This method is supported for the benefit of hash tables such as those
provided byHashMap.
Thus it is intended to be used by other objects. If hashCode wouldn't be declared public this functionality would be limited usable.
Object.equals is a symmetric method. If Object.equals wouldn't be declared public, suppose we have a local variable b of a type from another package and whose equals method isn't visible to this. We want to ckeck if b and this are equal. We couldn't call b != null && b.equals(this) but we could still call this.equals(b). Does it makes sense to limit a symmetric method to be callable by one of both objects only?
See also Comparable.
answered Nov 22 '18 at 15:29
LuCioLuCio
2,8671823
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
Because you want to call hashcode and equals methods from the outside of that given class.
protected allows access only from the same package and extending classes.
answered Nov 22 '18 at 11:01
AntoniossssAntoniossss
16.1k12354
Hi @antoniossss, thanks for response, but Object class is root package for all the classes, so I believe it should be available to all the classes. one more reason why clone and finalize methods are protected is to make overriding it with either protected or public visibility. so why not hashcode and equals
– Vignesh
Nov 23 '18 at 6:45
You are wrong.protectedmethods of classa.b.Classare visible in packagea.bbut not ina.b.z
– Antoniossss
Nov 23 '18 at 8:13
add a comment |
Because you want to call hashcode and equals methods from the outside of that given class.
protected allows access only from the same package and extending classes.
answered Nov 22 '18 at 11:01
AntoniossssAntoniossss
16.1k12354
Hi @antoniossss, thanks for response, but Object class is root package for all the classes, so I believe it should be available to all the classes. one more reason why clone and finalize methods are protected is to make overriding it with either protected or public visibility. so why not hashcode and equals
– Vignesh
Nov 23 '18 at 6:45
You are wrong.protectedmethods of classa.b.Classare visible in packagea.bbut not ina.b.z
– Antoniossss
Nov 23 '18 at 8:13
add a comment |
Because you want to call hashcode and equals methods from the outside of that given class.
protected allows access only from the same package and extending classes.
answered Nov 22 '18 at 11:01
AntoniossssAntoniossss
16.1k12354
Because you want to call hashcode and equals methods from the outside of that given class.
protected allows access only from the same package and extending classes.
answered Nov 22 '18 at 11:01
AntoniossssAntoniossss
16.1k12354
edited Nov 22 '18 at 11:07
answered Nov 22 '18 at 11:01
AntoniossssAntoniossss
16.1k12354
answered Nov 22 '18 at 11:01
AntoniossssAntoniossss
16.1k12354
answered Nov 22 '18 at 11:01
AntoniossssAntoniossss
16.1k12354
16.1k12354
Hi @antoniossss, thanks for response, but Object class is root package for all the classes, so I believe it should be available to all the classes. one more reason why clone and finalize methods are protected is to make overriding it with either protected or public visibility. so why not hashcode and equals
– Vignesh
Nov 23 '18 at 6:45
You are wrong.protectedmethods of classa.b.Classare visible in packagea.bbut not ina.b.z
– Antoniossss
Nov 23 '18 at 8:13
add a comment |
Hi @antoniossss, thanks for response, but Object class is root package for all the classes, so I believe it should be available to all the classes. one more reason why clone and finalize methods are protected is to make overriding it with either protected or public visibility. so why not hashcode and equals
– Vignesh
Nov 23 '18 at 6:45
You are wrong.protectedmethods of classa.b.Classare visible in packagea.bbut not ina.b.z
– Antoniossss
Nov 23 '18 at 8:13
Hi @antoniossss, thanks for response, but Object class is root package for all the classes, so I believe it should be available to all the classes. one more reason why clone and finalize methods are protected is to make overriding it with either protected or public visibility. so why not hashcode and equals
– Vignesh
Nov 23 '18 at 6:45
Hi @antoniossss, thanks for response, but Object class is root package for all the classes, so I believe it should be available to all the classes. one more reason why clone and finalize methods are protected is to make overriding it with either protected or public visibility. so why not hashcode and equals
– Vignesh
Nov 23 '18 at 6:45
You are wrong.
protected methods of class a.b.Class are visible in package a.b but not in a.b.z– Antoniossss
Nov 23 '18 at 8:13
You are wrong.
protected methods of class a.b.Class are visible in package a.b but not in a.b.z– Antoniossss
Nov 23 '18 at 8:13
add a comment |
You "understand the purpose of making the clone and finalize method as protected". But what is the purpose actually?
Calling Object.clone will throw an exception if the method isn't overridden and if Cloneable isn't implemented. Thus this method isn't ready to use.
Object.finalize is according to JavaDoc "called by the garbage collector". Thus it is for internal usage only.
In contrast to these both methods are Object.equals and Object.hashCode ready to use and not for internal usage.
The JavaDoc of Object.hashCode says:
This method is supported for the benefit of hash tables such as those
provided byHashMap.
Thus it is intended to be used by other objects. If hashCode wouldn't be declared public this functionality would be limited usable.
Object.equals is a symmetric method. If Object.equals wouldn't be declared public, suppose we have a local variable b of a type from another package and whose equals method isn't visible to this. We want to ckeck if b and this are equal. We couldn't call b != null && b.equals(this) but we could still call this.equals(b). Does it makes sense to limit a symmetric method to be callable by one of both objects only?
See also Comparable.
answered Nov 22 '18 at 15:29
LuCioLuCio
2,8671823
add a comment |
You "understand the purpose of making the clone and finalize method as protected". But what is the purpose actually?
Calling Object.clone will throw an exception if the method isn't overridden and if Cloneable isn't implemented. Thus this method isn't ready to use.
Object.finalize is according to JavaDoc "called by the garbage collector". Thus it is for internal usage only.
In contrast to these both methods are Object.equals and Object.hashCode ready to use and not for internal usage.
The JavaDoc of Object.hashCode says:
This method is supported for the benefit of hash tables such as those
provided byHashMap.
Thus it is intended to be used by other objects. If hashCode wouldn't be declared public this functionality would be limited usable.
Object.equals is a symmetric method. If Object.equals wouldn't be declared public, suppose we have a local variable b of a type from another package and whose equals method isn't visible to this. We want to ckeck if b and this are equal. We couldn't call b != null && b.equals(this) but we could still call this.equals(b). Does it makes sense to limit a symmetric method to be callable by one of both objects only?
See also Comparable.
answered Nov 22 '18 at 15:29
LuCioLuCio
2,8671823
add a comment |
You "understand the purpose of making the clone and finalize method as protected". But what is the purpose actually?
Calling Object.clone will throw an exception if the method isn't overridden and if Cloneable isn't implemented. Thus this method isn't ready to use.
Object.finalize is according to JavaDoc "called by the garbage collector". Thus it is for internal usage only.
In contrast to these both methods are Object.equals and Object.hashCode ready to use and not for internal usage.
The JavaDoc of Object.hashCode says:
This method is supported for the benefit of hash tables such as those
provided byHashMap.
Thus it is intended to be used by other objects. If hashCode wouldn't be declared public this functionality would be limited usable.
Object.equals is a symmetric method. If Object.equals wouldn't be declared public, suppose we have a local variable b of a type from another package and whose equals method isn't visible to this. We want to ckeck if b and this are equal. We couldn't call b != null && b.equals(this) but we could still call this.equals(b). Does it makes sense to limit a symmetric method to be callable by one of both objects only?
See also Comparable.
answered Nov 22 '18 at 15:29
LuCioLuCio
2,8671823
You "understand the purpose of making the clone and finalize method as protected". But what is the purpose actually?
Calling Object.clone will throw an exception if the method isn't overridden and if Cloneable isn't implemented. Thus this method isn't ready to use.
Object.finalize is according to JavaDoc "called by the garbage collector". Thus it is for internal usage only.
In contrast to these both methods are Object.equals and Object.hashCode ready to use and not for internal usage.
The JavaDoc of Object.hashCode says:
This method is supported for the benefit of hash tables such as those
provided byHashMap.
Thus it is intended to be used by other objects. If hashCode wouldn't be declared public this functionality would be limited usable.
Object.equals is a symmetric method. If Object.equals wouldn't be declared public, suppose we have a local variable b of a type from another package and whose equals method isn't visible to this. We want to ckeck if b and this are equal. We couldn't call b != null && b.equals(this) but we could still call this.equals(b). Does it makes sense to limit a symmetric method to be callable by one of both objects only?
See also Comparable.
answered Nov 22 '18 at 15:29
LuCioLuCio
2,8671823
edited yesterday
answered Nov 22 '18 at 15:29
LuCioLuCio
2,8671823
answered Nov 22 '18 at 15:29
LuCioLuCio
2,8671823
answered Nov 22 '18 at 15:29
LuCioLuCio
2,8671823
2,8671823
add a comment |
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Simply put, because you would like to use these outside of the class
– Ivan Kaloyanov
Nov 22 '18 at 11:01