ArrayIndexOutOfBoundsException after assert statement

Question

I have a String array tmp got by String[] tmp = line.split(",");

Then,

I got java.lang.ArrayIndexOutOfBoundsException: 3 on code

assert tmp.length == 4;
int r = Integer.parseInt(tmp[3]);   ----error line

and java.lang.ArrayIndexOutOfBoundsException: 2 on code

assert tmp.length == 3;
String name = tmp[2];    -----error line

I do not think this error is reasonable. The assert statement passes correctly and how can a array with .length=4 having no element indexed 3? Could anyone tell me why...

Possible duplicate of [What causes a java.lang.ArrayIndexOutOfBoundsException and how do I prevent it?](https://stackoverflow.com/questions/5554734/what-causes-a-java-lang-arrayindexoutofboundsexception-and-how-do-i-prevent-it) — Nikolas Charalambidis, Jun 06 '18 at 09:53
@Nikolas I have just read this post before I asked. The most important part is different, which is that I have the `assert` — Litchy, Jun 06 '18 at 09:56
@YassinHajaj OH...is there a choice? I thought it is always activated — Litchy, Jun 06 '18 at 09:56
@Litchy Nope it is deactivated by default. If you use Eclipse you can look at the following post : https://stackoverflow.com/questions/11415160/how-to-enable-the-java-keyword-assert-in-eclipse-program-wise — Yassin Hajaj, Jun 06 '18 at 09:57
@Litchy Alright I'll add an answer to help future users encountering the same problem. — Yassin Hajaj, Jun 06 '18 at 10:06

score 3 · Accepted Answer · answered Jun 06 '18 at 10:08

3

As stated in the comments, the problem here is that you did not activate the assertions in the JVM options

In command line java MyProgram -ea

For Eclipse, see this answer.

For IntelliJ, see this answer.

answered Jun 06 '18 at 10:08

Yassin Hajaj

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score 2 · Answer 2 · answered Jun 06 '18 at 10:23

By default, assertions are disabled and you should enable them using either of below command-line switches:

-ea
-enableassertions

You can check the documentation for more package and sub-package finer grained activation.

For arguments or variables validation, you should use a dedicated Assertion library or simply craft yours.

A lightweight and fluent one should be the valid4j:

//...
Assertive.ensure(tmp.length == 4, "The split result array must have 4 elements: (%d)", tmp.length);

ArrayIndexOutOfBoundsException after assert statement

2 Answers2