CODEWITHSUNDEEP
java
EdgeCase
EdgeCase

Reputation: 4827

Insert Elements to an ArrayList from ordered SQL

I am loading objects in an Java ArrayList from a SQL Query with an ORDER BY clause.

(1) Can I access that ArrayList with a foreach loop and get them back in the order in which they were loaded?

(2) Similarly, can I consistently get the elements in the same SQL order by using get(n)? I.e. if the 3rd element in the SQL rowset was "x", will get(2) always retrieve that?

Upvotes: 0

Views: 457

Answers (3)

Syam
Syam

Reputation: 1212

Yes ArrayList in Java is Ordered Collection. API says
List is an ordered collection (also known as a sequence). The user of this interface has precise control over where in the list each element is inserted. The user can access elements by their integer index (position in the list), and search for elements in the list.

When you load from SQL to ArrayList you should exactly insert in the same order as of SQL. code snippet should be like this 

for (Each row starting from 0 in SQL) {
  // add to arraylist using add method
  list.add(sqlvalue);
}

for each iterator also maintain the same order.

Upvotes: 1

amicngh
amicngh

Reputation: 7899

Can I access that ArrayList with a foreach loop and get them back in the order in which they were loaded?

Yes, List's are ordered collection .

Similarly, can I consistently get the elements in the same SQL order by using get(n)? I.e. if the 3rd element in the SQL rowset was "x", will get(2) always retrieve that?

Yes , As i said they are ordered , in the order they are inserted they can be retrieved in the same order. 

List<String> ls=new ArrayList<String>();
        ls.add("A");
        ls.add("B");
        ls.add("C");

        for(String s:ls)
            System.out.println(s);

        System.out.println(ls.get(1));

Results:

A
B
C
B

Upvotes: 1

Andrey Borisov
Andrey Borisov

Reputation: 3170

sure you can, this is how List works. still you can use http://docs.oracle.com/javase/1.4.2/docs/api/java/util/LinkedHashSet.html

Upvotes: 1

Related Questions