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

Go to download

Show more of this group Show more artifacts with this name
Show all versions of sanity4j Show documentation

Sanity4J was created to simplify running multiple static code analysis tools on the Java projects. It provides a single entry point to run all the selected tools and produce a consolidated report, which presents all findings in an easily accessible manner.

The newest version!



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.
    
		
		
		    
    			This rule is defined by the following XPath expression:
    			
    			
            
//PrimarySuffix[@Image='equals' and not(../PrimaryPrefix/Literal)]
 /../PrimarySuffix/Arguments/ArgumentList/Expression
 /PrimaryExpression/PrimaryPrefix
 /Name[@Image = ./../../../../../../../../../../Expression/ConditionalAndExpression
 /EqualityExpression[@Image="!=" and count(./preceding-sibling::*)=0 and
 ./PrimaryExpression/PrimaryPrefix/Literal/NullLiteral]
  /PrimaryExpression/PrimaryPrefix/Name/@Image]
        
        
  
		    
		    
	    
	    
        
        
        Example:
            
                    

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
}
}
}
}