What does the period do?

[Peter Park]

Beginner here,

This is from another thread:  https://coderanch.com/t/245950/certification/Exam-Prep-post-increment I read but I could not understand what the JMM125.i on the last line of code means. Especially that period between the JMM125 and i. What does it do to make it come out as a 3?

Explanation? Thank you!

public class JMM125 {
static int i;
public static void main(String[] args) {
for (i = 1; i < 3; i++) {
System.out.println(i);
}
for (int i = 1; i < 3; i++) {
System.out.println(i);
}
int i;
for (i = 0; i < 2; i++) {
System.out.println(i);
}
System.out.println(JMM125.i);
}
}

Product:

1
2
1
2
0
1
3

[Campbell Ritchie]

I think the idea is to show that the three local variables called i are distinct from the static field called i. Note the scopes of the three local variables must not overlap.

[Knute Snortum]

On line 3 you have an instance class variable called i.  That variable can be seen in all methods except when it is hidden by a local variable.  On line 12 you have a local variable also called i that hides the instance class variable.  Line 16 accesses the instance class variable directly.  It is 3 because you use it in line 6.

[Edit: missed that the first i is static.]

[Campbell Ritchie]

My mistake: there are only two local variables.

[Anton Golovin]

 

Peter Park wrote:Beginner here,

This is from another thread:  https://coderanch.com/t/245950/certification/Exam-Prep-post-increment I read but I could not understand what the JMM125.i on the last line of code means. Especially that period between the JMM125 and i. What does it do to make it come out as a 3?

Explanation? Thank you!

public class JMM125 {
static int i;
public static void main(String[] args) {
for (i = 1; i < 3; i++) {
System.out.println(i);
}
for (int i = 1; i < 3; i++) {
System.out.println(i);
}
int i;
for (i = 0; i < 2; i++) {
System.out.println(i);
}
System.out.println(JMM125.i);
}
}

Product:

1
2
1
2
0
1
3

Hi, Peter,

When you loop within the static main method, you don't declare a new int variable in your loop, you assign a value to one that already exists, the static one. You don't have to qualify the static variable's name with class name if you don't want to. It's a tricky piece of code. I would always qualify for readability.

So basically, it increments the static i variable and then prints out its last value.

With best regards,

Anton.

[Peter Park]

Thanks for the replies! I think I understand it.