resources.report.rules.pmd.UnusedNullCheckInEquals.html Maven / Gradle / Ivy

Go to download


UnusedNullCheckInEquals

UnusedNullCheckInEquals

After checking an object reference for null, you should invoke equals() on that object rather than passing it to another object’s equals() method.


        
(//PrimaryPrefix[ends-with(Name/@Image, '.equals') and Name/@Image != 'Arrays.equals'] | //PrimarySuffix[@Image='equals' and not(../PrimaryPrefix/Literal)])
 /following-sibling::PrimarySuffix/Arguments/ArgumentList/Expression
 /PrimaryExpression[count(PrimarySuffix)=0]/PrimaryPrefix
 /Name[@Image = ./../../../../../../../../../../Expression/ConditionalAndExpression
 /EqualityExpression[@Image="!=" and count(./preceding-sibling::*)=0 and
 ./PrimaryExpression/PrimaryPrefix/Literal/NullLiteral]
  /PrimaryExpression/PrimaryPrefix/Name/@Image]
        

Example(s):


		
public class Test {

  public String method1() { return "ok";}
  public String method2() { return null;}

  public void method(String a) {
    String b;
	// I don't know it method1() can be "null"
	// but I know "a" is not null..
	// I'd better write a.equals(method1())
	
	if (a!=null && method1().equals(a)) { // will trigger the rule
	//whatever
	}
	
	if (method1().equals(a) && a != null) { // won't trigger the rule
	//whatever
	}
	
	if (a!=null && method1().equals(b)) { // won't trigger the rule
	//whatever
	}
	
	if (a!=null && "LITERAL".equals(a)) { // won't trigger the rule
	//whatever
	}
	
	if (a!=null && !a.equals("go")) { // won't trigger the rule
	a=method2();
	if (method1().equals(a)) {
	//whatever
	}
  }
}
}