UML for local variables

Question

If I have 2 java classes, one class's method contains method variable that is a reference to the second class (not instance variable). How do I link these classes in UML diagram? I am giving an example for better clearance of question:

class A{
     methodA(B b){
      <do something>
} 
}

class B{

}

Answer 1

It's a dependency, kind of weak relationship. In this case it is establish only while the method execution and is typically merely indicated with a generic dependency:

Stronger kinds of relationships, like association or composition usually suggest member variables.

Answer 2

If any class contains the reference of any other class (other than instance variable) then this relationship is know as composition Relationship. It can be depicted in UML using a class relationship. The black diamond represents composition in UML class diagram. The arrowhead on the other end of the relationship denotes that the relationship is navigable in only one direction.