CODEWITHSUNDEEP
javasonarqube
Reginald
Reginald

Reputation: 818

Sonar Equals Avoid Null Violation

Fixing sonar violations and got a warning " Equals Avoid Null:
String literal expressions should be on the left side of an equals comparison." for:

if (title != null && !title.equals("")) {
//rest of loop
}

I changed it to:

if(!("").equals(title) && title != null){
//rest of loop
}

Is that change okay? Will it fix the violation? Could somebody possibly explain to me why the original is a violation? I don't understand the issue and have read: https://sonar43.spring.io/rules/show/checkstyle:com.puppycrawl.tools.checkstyle.checks.coding.EqualsAvoidNullCheck?layout=false

amongst one or two other articles, but I stil don't see what the problem is...

Upvotes: 0

Views: 4535

Answers (1)

keyser
keyser

Reputation: 19189

The warning is telling you that it's not sure that title won't be null. A literal, however, such as your empty string, can never be null by definition. And since equals can handle null as an argument you're avoiding a potential NullPointerException by writing <literal>.equals(<somebject>). If you're not using title within the if statement there's no need for further null-checking:

if(!"".equals(title)){
    //rest of loop
}

However, since you're checking if something doesn't equal a literal it makes little sense to let null values pass through.

The docs also has this related note:

Also, it is pretty common to see null check right before equals comparisons which is not necessary [...]

Upvotes: 2

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