match evaluation vs. pre increment

[sterf]

"7.07".substring(0,1).matches("[0-9]");

vs.

int i=0;"7.07".substring(i,++i).matches("[0-9]")

The first expression is true, the second is false. Why.
To clarify, I expected that ++i would be executed before the substring was calculated and matched.

[fiveironfrnzy80]

I ran the following code and got true for both...

package test;

public class Main {

	public static void main(String[] args) {
		boolean test1;
		boolean test2;
		test1 = "7.07".substring(0,1).matches("[0-9]");
		int i=0;
		test2 = "7.07".substring(i,++i).matches("[0-9]");
		System.out.println(test1);
		System.out.println(test2);
	}

}

[sterf]

I ran the following code and got true for both...

package test;

public class Main {

	public static void main(String[] args) {
		boolean test1;
		boolean test2;
		test1 = "7.07".substring(0,1).matches("[0-9]");
		int i=0;
		test2 = "7.07".substring(i,++i).matches("[0-9]");
		System.out.println(test1);
		System.out.println(test2);
	}

}

Thank you for your reply. Your code runs both times true on my machine too now. My code did return false however, it was inside a loop. I still have it in my display screen in eclipse
"7.07".substring(firstDigitIndex, ++firstDigitIndex).matches("[0-9]")
(boolean) false

Very suspicious.

[pbrockway2]

It would be easier if you posted the actual code whose behaviour you can't understand.

Par it down to something small and runnable that others can try for themselves.