Effective way to test if object is null

Question

What is better use in order to check if object is null.

To check if the object is null or to set a flag for it. By saying better im looking for performance (faster and safer).

public class A
{

Object test;
boolean isTestObjectSet;

public A(Object test)
{
this.test = test;
isTestObjectSet = true;
}

public A()
{

}

public void doSomething()
{

if(test != null)
//do something

//VS

if(isTestObjectSet)
//do something


}
}

Answer 1

Using isTestObjectSet is just making things more complicated than they need to be. Just use test != null : it better conveys your intention and doesn't force you to keep this isTestObjectSet variable in-sync with whether or not test is set. There is absolutely no performance difference between the two variants.

Answer 2

In my opinion - explicit checks (comparing to 'null') is faster, in terms not cluttering your code with many intermediary boolean variables. Safer? Both of the checks are boolean checks, so it is always 'true'/'false' comparison.