Question

Code:

public class MyClass {
 private Map<Integer,String> myMap;
 ...........................


 void methodFillMap(){
    myMap=new HashMap<Integer, String>();

  .....................
  }
}

Or better like:

public class MyClass {
 private Map<Integer,String> myMap=new HashMap<Integer, String>();
 ...........................


 void methodFillMap(){
    myMap.put(.....);

  .....................
  }

}

Are these 2 ways of creating map the same by efficiency and functionality?

Answer 1

No they are different functionally. In your first case every time the method methodFillMap is called a new map is created and you will lose information from the old Map whereas in your second case the object will persist with the information.