clearing or set null to objects in java

Question

I was recently looking into freeing up memory occupied by Java objects. While doing that I got confused about how objects are copied (shallow/deep) in Java and how to avoid

Answer 1

To clear the variable

According to my knowledge,

If you are going to reuse the variable, then use

               Object.clear();

If you are not going to reuse, then define

               Object=null;

Note: Compare to removeAll(), clear() is faster.

Please correct me, If I am wrong....