检查 java 中的条件导致错误

Question

I have the below piece of code in which under if condition I am getting the sonar findings that is Strings literals should be placed on the left side when checking for equality. Please advise how to overcome this.

final String aviid = avcMaster.getAVMaster().getAviiId();
if ((!aviid.equals("44")) || (!aviid.equals("55"))) { // ** Sonar Issue **//
    final String defaultAiId = "88";
    deviceElement.setAttribute("avi", defaultAiId);
}
else{
    deviceElement.setAttribute("avi", aviid);
}

Answer 1

Comparison between String variable and String literal

• calling the method on the variable: if the variable is null you'll get a NullPointerException

   aviid.equals("44")

• calling the method on the literal: you can't get a NPE and you'll have false in case the variable holds null

   "44".equals(aviid)

Sonar warns you because for it, it's better to get false than NPE , but the code is your choice.

---

Also your test is wrong because it'll always be true, as you can't have 44 and 55 at the same time, one of them will be true, you surely meant && , also you'd better do it the other way you wouldn't need the negation.

if ((!aviid.equals("44")) && (!aviid.equals("55"))) { 

And to do it shorter (from comments)

deviceElement.setAttribute("avi", aviid.matches("44|55") ? aviid : "88");