RuleDescriptionExampleKPI
String Concatenation In LoggingInstead of string concatenation use parameterized logging. Concatenation is calculated before the condition check. If you call your logging framework multiple times which turns to be false, this effort will be a waste of time. E.g. if you call your logging framework 10K times conditionally and all of them evaluates to be false, concatenation will happen 10K times.Non-compliant code:
class Demo {
//If log level is not debug, then also string concatenation will happen.
public void process1() {
logger.debug("Comparing objects: " + object1 + " and " + object2);
}
}

Compliant code:
class Demo {
public void process2() {
//Compliant code
logger.debug("Comparing objects: {} and {}",object1, object2);
}
}		Efficiency
Tightly Coupled ClassA spring component such as repository, service and controller should auto-wire the interface, instead of its implementation class. Ignoring this, will increase tight coupling among the classes Non-compliant code:
class Demo {
@RequestMapping("/users")
public class UserController
{
@Autowire
UserServiceImpl userServiceImpl;
}
}

Compliant code:
class Demo {
@RequestMapping("/users")
public class UserController
{
@Autowire
UserService userService;
}
}		Maintainability