Is Java's assertEquals method reliable?

java string junit junit4
DivideByHero picture DivideByHero · Jul 29, 2009 · Viewed 298.4k times · Source

I know that == has some issues when comparing two Strings. It seems that String.equals() is a better approach. Well, I'm doing JUnit testing and my inclination is to use assertEquals(str1, str2). Is this a reliable way to assert two Strings contain the same content? I would use assertTrue(str1.equals(str2)), but then you don't get the benefit of seeing what the expected and actual values are on failure.

On a related note, does anyone have a link to a page or thread that plainly explains the problems with str1 == str2?

Answer

jjnguy picture jjnguy · Jul 29, 2009

You should always use .equals() when comparing Strings in Java.

JUnit calls the .equals() method to determine equality in the method assertEquals(Object o1, Object o2).

So, you are definitely safe using assertEquals(string1, string2). (Because Strings are Objects)

Here is a link to a great Stackoverflow question regarding some of the differences between == and .equals().

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