Method on how to access a variable?
I'm currently learning Java, and one of the examples in the textbook is as follows:
class Circle{
private double radius;
private double area;
public void setRadius(double r){
radius = r;
setArea(Math.PI * radius * radius);
}
public void setArea(double a){
area = a;
}
Looking at the setRadius method, is there a style preference/difference between writing what's above VS writing the following?
public void setRadius(double r){
radius = r;
setArea(Math.PI*r*r);
}
One of my classmates is making the argument that one should use the parameter r instead of the private variable radius because a public method shouldn't have direct access to a private variable unless it's by using a getter. Is this more of a style preference or is he right in that public methods directly accessing private methods is bad?
java
asked Nov 13 at 3:48
Tyler
147211
|
show 1 more comment
I'm currently learning Java, and one of the examples in the textbook is as follows:
class Circle{
private double radius;
private double area;
public void setRadius(double r){
radius = r;
setArea(Math.PI * radius * radius);
}
public void setArea(double a){
area = a;
}
Looking at the setRadius method, is there a style preference/difference between writing what's above VS writing the following?
public void setRadius(double r){
radius = r;
setArea(Math.PI*r*r);
}
One of my classmates is making the argument that one should use the parameter r instead of the private variable radius because a public method shouldn't have direct access to a private variable unless it's by using a getter. Is this more of a style preference or is he right in that public methods directly accessing private methods is bad?
java
asked Nov 13 at 3:48
Tyler
147211
2
It depends on requirement...if you see in Circle class there is <private double radius;> instance variable, they just want to set radius value in that variable as well as wanted to calculate area and again set to instance variable <private double area;>
– Arun Kumar
Nov 13 at 3:54
6
InsetAreayou have a bug; it should bethis.area = a;notarea = area;
– Elliott Frisch
Nov 13 at 3:55
@ElliottFrisch Apologies, that wasn't in the textbook; I just wrote it quickly for this question. I'll change it.
– Tyler
Nov 13 at 3:56
5
because a public method shouldn't have direct access to a private variable I disagree.
– Elliott Frisch
Nov 13 at 3:58
2
Your classmate is wrong. Public methods access private fields all the time.
– Dawood ibn Kareem
Nov 13 at 3:59
|
show 1 more comment
I'm currently learning Java, and one of the examples in the textbook is as follows:
class Circle{
private double radius;
private double area;
public void setRadius(double r){
radius = r;
setArea(Math.PI * radius * radius);
}
public void setArea(double a){
area = a;
}
Looking at the setRadius method, is there a style preference/difference between writing what's above VS writing the following?
public void setRadius(double r){
radius = r;
setArea(Math.PI*r*r);
}
One of my classmates is making the argument that one should use the parameter r instead of the private variable radius because a public method shouldn't have direct access to a private variable unless it's by using a getter. Is this more of a style preference or is he right in that public methods directly accessing private methods is bad?
java
asked Nov 13 at 3:48
Tyler
147211
I'm currently learning Java, and one of the examples in the textbook is as follows:
class Circle{
private double radius;
private double area;
public void setRadius(double r){
radius = r;
setArea(Math.PI * radius * radius);
}
public void setArea(double a){
area = a;
}
Looking at the setRadius method, is there a style preference/difference between writing what's above VS writing the following?
public void setRadius(double r){
radius = r;
setArea(Math.PI*r*r);
}
One of my classmates is making the argument that one should use the parameter r instead of the private variable radius because a public method shouldn't have direct access to a private variable unless it's by using a getter. Is this more of a style preference or is he right in that public methods directly accessing private methods is bad?
java
java
asked Nov 13 at 3:48
Tyler
147211
asked Nov 13 at 3:48
Tyler
147211
edited Nov 13 at 3:56
asked Nov 13 at 3:48
Tyler
147211
asked Nov 13 at 3:48
Tyler
147211
asked Nov 13 at 3:48
Tyler
147211
147211
2
It depends on requirement...if you see in Circle class there is <private double radius;> instance variable, they just want to set radius value in that variable as well as wanted to calculate area and again set to instance variable <private double area;>
– Arun Kumar
Nov 13 at 3:54
6
InsetAreayou have a bug; it should bethis.area = a;notarea = area;
– Elliott Frisch
Nov 13 at 3:55
@ElliottFrisch Apologies, that wasn't in the textbook; I just wrote it quickly for this question. I'll change it.
– Tyler
Nov 13 at 3:56
5
because a public method shouldn't have direct access to a private variable I disagree.
– Elliott Frisch
Nov 13 at 3:58
2
Your classmate is wrong. Public methods access private fields all the time.
– Dawood ibn Kareem
Nov 13 at 3:59
|
show 1 more comment
2
It depends on requirement...if you see in Circle class there is <private double radius;> instance variable, they just want to set radius value in that variable as well as wanted to calculate area and again set to instance variable <private double area;>
– Arun Kumar
Nov 13 at 3:54
6
InsetAreayou have a bug; it should bethis.area = a;notarea = area;
– Elliott Frisch
Nov 13 at 3:55
@ElliottFrisch Apologies, that wasn't in the textbook; I just wrote it quickly for this question. I'll change it.
– Tyler
Nov 13 at 3:56
5
because a public method shouldn't have direct access to a private variable I disagree.
– Elliott Frisch
Nov 13 at 3:58
2
Your classmate is wrong. Public methods access private fields all the time.
– Dawood ibn Kareem
Nov 13 at 3:59
2
2
It depends on requirement...if you see in Circle class there is <private double radius;> instance variable, they just want to set radius value in that variable as well as wanted to calculate area and again set to instance variable <private double area;>
– Arun Kumar
Nov 13 at 3:54
It depends on requirement...if you see in Circle class there is <private double radius;> instance variable, they just want to set radius value in that variable as well as wanted to calculate area and again set to instance variable <private double area;>
– Arun Kumar
Nov 13 at 3:54
6
6
In
setArea you have a bug; it should be this.area = a; not area = area;– Elliott Frisch
Nov 13 at 3:55
In
setArea you have a bug; it should be this.area = a; not area = area;– Elliott Frisch
Nov 13 at 3:55
@ElliottFrisch Apologies, that wasn't in the textbook; I just wrote it quickly for this question. I'll change it.
– Tyler
Nov 13 at 3:56
@ElliottFrisch Apologies, that wasn't in the textbook; I just wrote it quickly for this question. I'll change it.
– Tyler
Nov 13 at 3:56
5
5
because a public method shouldn't have direct access to a private variable I disagree.
– Elliott Frisch
Nov 13 at 3:58
because a public method shouldn't have direct access to a private variable I disagree.
– Elliott Frisch
Nov 13 at 3:58
2
2
Your classmate is wrong. Public methods access private fields all the time.
– Dawood ibn Kareem
Nov 13 at 3:59
Your classmate is wrong. Public methods access private fields all the time.
– Dawood ibn Kareem
Nov 13 at 3:59
|
show 1 more comment
2 Answers
2
active
oldest
votes
In this case both method call are correct
setArea(Math.PI * radius * radius);
and
setArea(Math.PI*r*r);
public method shouldn't have direct access to a private variable unless it's by using a getter
I don't agree for this. because getter also a public method and no meaning of this sentence.
answered Nov 13 at 4:00
janith1024
7643916
1
getter is also a public method but have a look at this answer to see why it still is a good practice
– Kartik
Nov 13 at 4:06
add a comment |
That code feels weird. Usually, when you're calling a set method, or a setter, you are explicitly setting a value, and nothing else. The setArea method call seems out of place, since that is now a side effect of the stated method call, which only specifies setRadius.
IMHO, the area in the class should be calculated, using the radius, once requested, instead of storing both the radius and the area. This is how the program should look:
class Circle {
private double radius;
public void setRadius(double radius) {
this.radius = radius;
}
public double getRadius() {
return radius;
}
public double getArea(){
return Math.PI * radius * radius;
}
}
As you see above, the r vs radius question goes away completely.
answered Nov 13 at 4:08
mjuarez
9,65973751
In as far as the current question goes, I agree with you; however, the class should (arguably) overrideObject#equals(Object),hashCode()andtoString(). There might also be some value to making theradiusimmutable and using the constructor to set it.
– Elliott Frisch
Nov 13 at 4:50
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
In this case both method call are correct
setArea(Math.PI * radius * radius);
and
setArea(Math.PI*r*r);
public method shouldn't have direct access to a private variable unless it's by using a getter
I don't agree for this. because getter also a public method and no meaning of this sentence.
answered Nov 13 at 4:00
janith1024
7643916
1
getter is also a public method but have a look at this answer to see why it still is a good practice
– Kartik
Nov 13 at 4:06
add a comment |
In this case both method call are correct
setArea(Math.PI * radius * radius);
and
setArea(Math.PI*r*r);
public method shouldn't have direct access to a private variable unless it's by using a getter
I don't agree for this. because getter also a public method and no meaning of this sentence.
answered Nov 13 at 4:00
janith1024
7643916
1
getter is also a public method but have a look at this answer to see why it still is a good practice
– Kartik
Nov 13 at 4:06
add a comment |
In this case both method call are correct
setArea(Math.PI * radius * radius);
and
setArea(Math.PI*r*r);
public method shouldn't have direct access to a private variable unless it's by using a getter
I don't agree for this. because getter also a public method and no meaning of this sentence.
answered Nov 13 at 4:00
janith1024
7643916
In this case both method call are correct
setArea(Math.PI * radius * radius);
and
setArea(Math.PI*r*r);
public method shouldn't have direct access to a private variable unless it's by using a getter
I don't agree for this. because getter also a public method and no meaning of this sentence.
answered Nov 13 at 4:00
janith1024
7643916
answered Nov 13 at 4:00
janith1024
7643916
answered Nov 13 at 4:00
janith1024
7643916
answered Nov 13 at 4:00
janith1024
7643916
7643916
1
getter is also a public method but have a look at this answer to see why it still is a good practice
– Kartik
Nov 13 at 4:06
add a comment |
1
getter is also a public method but have a look at this answer to see why it still is a good practice
– Kartik
Nov 13 at 4:06
1
1
getter is also a public method but have a look at this answer to see why it still is a good practice
– Kartik
Nov 13 at 4:06
getter is also a public method but have a look at this answer to see why it still is a good practice
– Kartik
Nov 13 at 4:06
add a comment |
That code feels weird. Usually, when you're calling a set method, or a setter, you are explicitly setting a value, and nothing else. The setArea method call seems out of place, since that is now a side effect of the stated method call, which only specifies setRadius.
IMHO, the area in the class should be calculated, using the radius, once requested, instead of storing both the radius and the area. This is how the program should look:
class Circle {
private double radius;
public void setRadius(double radius) {
this.radius = radius;
}
public double getRadius() {
return radius;
}
public double getArea(){
return Math.PI * radius * radius;
}
}
As you see above, the r vs radius question goes away completely.
answered Nov 13 at 4:08
mjuarez
9,65973751
In as far as the current question goes, I agree with you; however, the class should (arguably) overrideObject#equals(Object),hashCode()andtoString(). There might also be some value to making theradiusimmutable and using the constructor to set it.
– Elliott Frisch
Nov 13 at 4:50
add a comment |
That code feels weird. Usually, when you're calling a set method, or a setter, you are explicitly setting a value, and nothing else. The setArea method call seems out of place, since that is now a side effect of the stated method call, which only specifies setRadius.
IMHO, the area in the class should be calculated, using the radius, once requested, instead of storing both the radius and the area. This is how the program should look:
class Circle {
private double radius;
public void setRadius(double radius) {
this.radius = radius;
}
public double getRadius() {
return radius;
}
public double getArea(){
return Math.PI * radius * radius;
}
}
As you see above, the r vs radius question goes away completely.
answered Nov 13 at 4:08
mjuarez
9,65973751
In as far as the current question goes, I agree with you; however, the class should (arguably) overrideObject#equals(Object),hashCode()andtoString(). There might also be some value to making theradiusimmutable and using the constructor to set it.
– Elliott Frisch
Nov 13 at 4:50
add a comment |
That code feels weird. Usually, when you're calling a set method, or a setter, you are explicitly setting a value, and nothing else. The setArea method call seems out of place, since that is now a side effect of the stated method call, which only specifies setRadius.
IMHO, the area in the class should be calculated, using the radius, once requested, instead of storing both the radius and the area. This is how the program should look:
class Circle {
private double radius;
public void setRadius(double radius) {
this.radius = radius;
}
public double getRadius() {
return radius;
}
public double getArea(){
return Math.PI * radius * radius;
}
}
As you see above, the r vs radius question goes away completely.
answered Nov 13 at 4:08
mjuarez
9,65973751
That code feels weird. Usually, when you're calling a set method, or a setter, you are explicitly setting a value, and nothing else. The setArea method call seems out of place, since that is now a side effect of the stated method call, which only specifies setRadius.
IMHO, the area in the class should be calculated, using the radius, once requested, instead of storing both the radius and the area. This is how the program should look:
class Circle {
private double radius;
public void setRadius(double radius) {
this.radius = radius;
}
public double getRadius() {
return radius;
}
public double getArea(){
return Math.PI * radius * radius;
}
}
As you see above, the r vs radius question goes away completely.
answered Nov 13 at 4:08
mjuarez
9,65973751
answered Nov 13 at 4:08
mjuarez
9,65973751
answered Nov 13 at 4:08
mjuarez
9,65973751
answered Nov 13 at 4:08
mjuarez
9,65973751
9,65973751
In as far as the current question goes, I agree with you; however, the class should (arguably) overrideObject#equals(Object),hashCode()andtoString(). There might also be some value to making theradiusimmutable and using the constructor to set it.
– Elliott Frisch
Nov 13 at 4:50
add a comment |
In as far as the current question goes, I agree with you; however, the class should (arguably) overrideObject#equals(Object),hashCode()andtoString(). There might also be some value to making theradiusimmutable and using the constructor to set it.
– Elliott Frisch
Nov 13 at 4:50
In as far as the current question goes, I agree with you; however, the class should (arguably) override
Object#equals(Object), hashCode() and toString(). There might also be some value to making the radius immutable and using the constructor to set it.– Elliott Frisch
Nov 13 at 4:50
In as far as the current question goes, I agree with you; however, the class should (arguably) override
Object#equals(Object), hashCode() and toString(). There might also be some value to making the radius immutable and using the constructor to set it.– Elliott Frisch
Nov 13 at 4:50
add a comment |
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2
It depends on requirement...if you see in Circle class there is <private double radius;> instance variable, they just want to set radius value in that variable as well as wanted to calculate area and again set to instance variable <private double area;>
– Arun Kumar
Nov 13 at 3:54
6
In
setAreayou have a bug; it should bethis.area = a;notarea = area;– Elliott Frisch
Nov 13 at 3:55
@ElliottFrisch Apologies, that wasn't in the textbook; I just wrote it quickly for this question. I'll change it.
– Tyler
Nov 13 at 3:56
5
because a public method shouldn't have direct access to a private variable I disagree.
– Elliott Frisch
Nov 13 at 3:58
2
Your classmate is wrong. Public methods access private fields all the time.
– Dawood ibn Kareem
Nov 13 at 3:59