Question

I want to make a method that will create ArrayLists, and name each one after an element in a existing ArrayList.
Like, ArrayList original is (abc, def, ghi, jkl)
and I want the method to create four ArrayLists, named abc, def, ghi, and jkl.

How to pull those strings (abc, def) out and use them to name the new ArrayLists?

I tried:

ArrayList original.get(0) = new ArrayList();

But Eclipse says misplaced construct

I tried:

String newName = original.get(count);  
ArrayList (newName) = new ArrayList();

But it says the left hand side of of an assignment must be a variable

If I take the newName out of parenthesis:

    String newName = original.get(count);
    ArrayList newName = new ArrayList();

It says duplicate local variable newName

Answer 1

In Java, you cannot name a variable based on the value of another variable. The compiler must know the names of all variables at compile-time. However, the return value of a method such as original.get(0) and values of variables are only known at run-time.

With that said, you can use the Map<String, List<String>> class to do what you are trying to do with dynamic variable names. You will just add your ArrayLists to the Map indexed on the String “names”.