How to programmatically test if assertions are enabled?

Question

One of the correct answers from OCP Java SE 6 Programmer Practice Exams is:

You can programmatically test wheather assertions have been enabled without throwing an AssertionError.

How can I do that?

Peter Lawrey · Accepted Answer · 2012-10-23T12:09:18.040

35

I use this

boolean assertOn = false;
// *assigns* true if assertions are on.
assert assertOn = true;

I am not sure this is the "official" way.

edited Oct 23 '12 at 12:09

answered Oct 23 '12 at 12:03

Peter Lawrey

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Every time `true` is `false` ;) – Peter Lawrey Oct 23 '12 at 12:05
2

And looking at @Joe's answer, apparently the "official" way, too. – Thilo Oct 23 '12 at 23:57
They even call it "straightforward", so please delete your comment again, @PeterLawrey :D – TheBlastOne Oct 24 '12 at 16:09
*I am not sure this is the "official" way* -- it's not. 2 beers fine for not knowing the core classes in Java (since 1.4) `Class.desiredAssertionStatus()` – bestsss Oct 27 '12 at 20:14
@Thilo, it's not the official way, it's a well defined API function in `Class` to do so. – bestsss Oct 27 '12 at 20:16

score 30 · Answer 2 · edited Mar 21 '23 at 08:50

30

I guess you should use Class.desiredAssertionStatus()

edited Mar 21 '23 at 08:50

Flow

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answered Oct 23 '12 at 12:02

Hakan Serce

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This avoids the possible "accidental assignment" warning that comes with the other approach. – Daniel Renshaw Apr 18 '14 at 09:57
7

Actually, from the javadoc: "Note that this method is not guaranteed to return the actual assertion status that was (or will be) associated with the specified class when it was (or will be) initialized.". So this answer seems incorrect to me, and you should consider Joe's answer. – FBB Apr 05 '15 at 14:30
@FBB, I'm guessing it should be safe to invoke this method from inside an instance of the class you are testing against (because the class is guaranteed to be initialized). – Gili May 01 '15 at 04:05
1

@Gili: "when it *was* (or will be) initialized". So, no, the javadoc states it is not safe, even if the class was correctly initialized. – FBB May 01 '15 at 11:12
@FBB the other answer has exactly the same issue, it only checks whether assertions are enabled at the point the assertion is (or isn't) evaluated. – OrangeDog Aug 15 '19 at 14:44

score 23 · Answer 3 · edited Nov 22 '13 at 22:00

The Oracle Java Tutorial provides information about how to do it...

http://docs.oracle.com/javase/7/docs/technotes/guides/language/assert.html

An excerpt from the tutorial

7. Why not provide a construct to query the assert status of the containing class?

Such a construct would encourage people to inline complex assertion code, which we view as a bad thing. Further, it is straightforward to query the assert status atop the current API, if you feel you must:
boolean assertsEnabled = false;
assert assertsEnabled = true; // Intentional side-effect!!!
// Now assertsEnabled is set to the correct value

score 1 · Answer 4 · answered Dec 02 '15 at 08:52

1

RuntimeMXBean mx = ManagementFactory.getRuntimeMXBean();
boolean assertionsEnabled = mx.getInputArguments().contains("-ea");

answered Dec 02 '15 at 08:52

cnmuc

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Assertions can be enabled per-class and package, and can be changed by instrumentation. – OrangeDog Aug 15 '19 at 14:46

score 1 · Answer 5 · answered Jun 01 '20 at 16:47

1

I'm using AssertsEnabled from jdk.nashorn.internal.

System.out.println(AssertsEnabled.assertsEnabled());
// "assertsEnabled()" returns boolean value

Maybe it helps someone.

answered Jun 01 '20 at 16:47

Hürkan Doğan

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score 0 · Answer 6 · answered Nov 28 '22 at 11:06

Official solution*:

Source: http://hg.openjdk.java.net/javadoc-next/api/nashorn/rev/fa79d912da1b#l1.38

* As official as it gets:

As mentioned by @Hurkan Dogan here there was a AssertsEnabled.assertsEnabled() api in nashorn package which is now deprecated. However, its implementation could be considered as the official solution.

Also note that this solution is also written in the official docs and mentioned by @Joe here

score -1 · Answer 7 · answered Sep 20 '19 at 03:45

-1

package io.github.baijifeilong.tmp;

import io.vavr.control.Try;

/**
 * Created by BaiJiFeiLong@gmail.com at 2019-04-18 09:12
 */
public class TmpApp {

    public static void main(String[] args) {
        Try.run(() -> {
            assert false;
        }).onSuccess($ -> {
            throw new RuntimeException("Assertion is not enabled");
        });
    }
}

Maybe help someone.

answered Sep 20 '19 at 03:45

BaiJiFeiLong

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OP asked specifically for a solution "without throwing an AssertionError" – Simon Aug 12 '22 at 20:15

score -1 · Answer 8 · answered Aug 11 '22 at 17:03

-1

boolean ea=false;
try { assert(false); }
catch(AssertionError e) { ea=true; }

answered Aug 11 '22 at 17:03

Christopher Mindus

1

OP asked specifically for a solution "without throwing an AssertionError" – Simon Aug 12 '22 at 20:15

How to programmatically test if assertions are enabled?

8 Answers8