In Java, can a final field be initialized from a constructor helper?
- by csj
I have a final non-static member:
private final HashMap<String,String> myMap;
I would like to initialize it using a method called by the constructor. Since myMap is final, my "helper" method is unable to initialize it directly. Of course I have options:
I could implement the myMap initialization code directly in the constructor.
MyConstructor (String someThingNecessary)
{
myMap = new HashMap<String,String>();
myMap.put("blah","blahblah");
// etc...
// other initialization stuff unrelated to myMap
}
I could have my helper method build the HashMap, return it to the constructor, and have the constructor then assign the object to myMap.
MyConstructor (String someThingNecessary)
{
myMap = InitializeMyMap(someThingNecessary);
// other initialization stuff unrelated to myMap
}
private HashMap<String,String> InitializeMyMap(String someThingNecessary)
{
HashMap<String,String> initializedMap = new HashMap<String,String>();
initializedMap.put("blah","blahblah");
// etc...
return initializedMap;
}
Method #2 is fine, however, I'm wondering if there's some way I could allow the helper method to directly manipulate myMap. Perhaps a modifier that indicates it can only be called by the constructor?
MyConstructor (String someThingNecessary)
{
InitializeMyMap(someThingNecessary);
// other initialization stuff unrelated to myMap
}
// helper doesn't work since it can't modify a final member
private void InitializeMyMap(String someThingNecessary)
{
myMap = new HashMap<String,String>();
myMap.put("blah","blahblah");
// etc...
}
