<div dir="ltr">Hi Daohan,<div>assert keyword is safely usable within production code. I don't think it has a significant performance impact if it is not enabled. Thus, you should not enable it in production unless you are debugging.</div><div><br></div><div>A package that uses assert extensively is java.lang.invoke package.</div><div><br></div><div>For me, these are the general notes for using assert:</div><div>1. They should not perform side-effects, such as changing variables. Having -ea, -esa and no flag run differently is definitely not desirable.</div><div>2. assert should not be used to defend against incorrect user inputs; it should only be used to ensure the correctness of internal states of your program, as assert is optional.</div><div><br></div><div>Chen Liang</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sun, Jul 16, 2023 at 12:54 AM Daohan Qu <<a href="mailto:quadhier@outlook.com">quadhier@outlook.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div>
<div dir="auto"><span style="color:rgb(0,0,0);font-family:Calibri,Helvetica,sans-serif;font-size:12pt">Dear developers,</span><br>
</div>
<div id="m_-4355526851130570919mail-editor-reference-message-container" dir="auto">
<div style="font-size:12pt;color:rgb(0,0,0)">
<font face="Calibri, Helvetica, sans-serif"><br>
</font></div>
<div style="font-size:12pt;color:rgb(0,0,0)">
<font face="Calibri, Helvetica, sans-serif">I'm a graduate student doing software engineering research.</font></div>
<div style="font-size:12pt;color:rgb(0,0,0)">
<span style="font-family:Calibri,Helvetica,sans-serif">Recently, I came across some interesting facts about Java
</span><code style="font-size:inherit;font-style:inherit;font-variant-ligatures:inherit;font-variant-caps:inherit;font-weight:inherit">assert</code><span style="font-family:Calibri,Helvetica,sans-serif"></span></div>
<div style="font-size:12pt;color:rgb(0,0,0)">
<span style="font-family:Calibri,Helvetica,sans-serif">statements </span><span style="font-family:Calibri,Helvetica,sans-serif">and have a few questions to ask.</span></div>
<div style="font-size:12pt;color:rgb(0,0,0)">
<div style="font-family:Calibri,Arial,Helvetica,sans-serif">
<span style="font-family:Calibri,Helvetica,sans-serif"><br>
</span></div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif">
<span style="font-family:Calibri,Helvetica,sans-serif">Although the <code>assert</code> keyword has been around for a long time and</span></div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif">
<span style="font-family:Calibri,Helvetica,sans-serif">is handy </span><span style="font-family:Calibri,Helvetica,sans-serif">for invariant checks, it does not seem to be widely used.</span></div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif">
<span style="font-family:Calibri,Helvetica,sans-serif">For example, in the famous
<code>j.u.c</code> packages, nearly all <code>assert</code></span></div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif">
<span style="font-family:Calibri,Helvetica,sans-serif">statements are commented out [1].</span><br>
</div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif">
<br>
</div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif">
<span style="font-family:Calibri,Helvetica,sans-serif">My questions are, should <code>
assert</code> be heavily used in Java programs,</span></div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif">
<span style="font-family:Calibri,Helvetica,sans-serif">especially in production code? And should we enable them in the</span></div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif">
<span style="font-family:Calibri,Helvetica,sans-serif">production code?</span></div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif">
<span style="font-family:Calibri,Helvetica,sans-serif"><br>
</span></div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif">
<span style="font-family:Calibri,Helvetica,sans-serif">By the way, I have read a useful article about using assertions in</span></div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif">
<span style="font-family:Calibri,Helvetica,sans-serif">Java [2], but it does not provide clear answers to my questions above.</span><br>
</div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif">
<span style="font-family:Calibri,Helvetica,sans-serif"><br>
</span></div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif">
<span style="font-family:Calibri,Helvetica,sans-serif">Thank you in advance!</span></div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif">
<br>
</div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif">
[1] <a href="https://github.com/search?q=repo%3Aopenjdk%2Fjdk+assert+path%3A%2F%5Esrc%5C%2Fjava.base%5C%2Fshare%5C%2Fclasses%5C%2Fjava%5C%2Futil%5C%2Fconcurrent%5C%2F%2F&type=code" target="_blank">https://github.com/search?q=repo%3Aopenjdk%2Fjdk+assert+path%3A%2F%5Esrc%5C%2Fjava.base%5C%2Fshare%5C%2Fclasses%5C%2Fjava%5C%2Futil%5C%2Fconcurrent%5C%2F%2F&type=code</a></div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif">
<span style="font-family:Calibri,Helvetica,sans-serif">[2] <a href="https://docs.oracle.com/javase/8/docs/technotes/guides/language/assert.html" target="_blank">https://docs.oracle.com/javase/8/docs/technotes/guides/language/assert.html</a></span></div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif">
<span style="font-family:Calibri,Helvetica,sans-serif"><br>
</span></div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif">
<span style="font-family:Calibri,Helvetica,sans-serif">Regards,</span></div>
<span style="font-family:Calibri,Helvetica,sans-serif">Daohan Qu</span><br>
</div>
<br>
</div>
</div>
</blockquote></div>