Interesting exploration of i++ and ++i in Java

An interesting discover of using i++ and ++i in Java loop

In general cases,

• i++ in Java means use the value of i and increase it by 1 after finish.
• ++i in Java means firstly increase i by 1 and use it afterwards

E.g.

int i = 1;
int output1 = i++;
i = 1;
int output2 = ++i;
System.out.println(output1);
System.out.println(output2);

Output:

1
2

However, in for loop:

for (int i = 1; i <= 5; i++) {
	System.out.println(i);
}

And:

for (int i = 1; i <= 5; ++i) {
	System.out.println(i);
}

The output are both:

1
2
3
4
5

These two methods can basically be rewritten as:

for (int i = 1; i <= 5;) {
	System.out.println(i);
	i++; // or ++i
}

After searching for reasons, a developer introduces in a blog that though the output for using i++ and ++i are the same, i++ needs a temporary variable to store the origin value before increasing, while there is no such a process in ++i. Therefore, the running time of i++ is longer than ++i, which is shown in the blog.

This shows that we should use ++i instead of i++, which can somehow improve the performance.