Difference between list.clear() and new instance

Question

In the below code,
List<String> test = new ArrayList<String)();
list.add("one");
list.add("two");
list.add("three");
list.clear();
(or)
list = new ArrayList<String)();
list.add("four");
list.add("five");
What is the difference between List.clear() and creating new instance for list?

Answer 1

1. Use code tags to post codes -- [code]CODE[/code] will display asCODEOr click the CODE button and paste your code between the {code} tags that appear.
2. Invoking clear() sets all the elements of the ArrayList to null and resets the size to 0.    public void clear() {
     modCount++;
     // Let gc do its work
     for (int i = 0; i < size; i++)
         elementData[i] = null;
     size = 0;
    }(modCount is used to detect concurrent modification and throw an Exception when needed)
Constructing a new ArrayList creates a new, different, empty ArrayList.
In many situations they might be equivalent, but not in a case where you have two or more variable references to the same ArrayList. Example (watch out for typos)ArrayList<String> stringsA = new ArrayList<String>();
ArrayList<String> stringsB = stringsA;
: // add elements to stringsA
: // stringsB refers to the same populated list
stringsA.clear(); // stringsB refers to the clear()ed list
: // add elements to stringsA again
stringsA = new ArrayList<String>(); // stringsB still refers to the populated listdb