Assigning null to Complex Type object in the context of memory in java

[sagngh8]

What is the meaning of assigning null to Complex Type object in the context of memory in java language.
Eg

while(true) //Approx 9000 times
{

Employee objEmployee = new Employee ();

objEmployee = //Put some value

objEmployee = null;
}

Does assigning null to the complex type make the object ready for garbage collection in java.Also
is it the way to efficient memory management in java.

Regards,
Sagar.