Nested Loop

[John Seals]

Greetings:

I am building a "tree view" and I need to be able to display the information in a specific way. Let's say my data looks like this:

(imagine this as a two column database)
a 1
a 2
a 3
b 4
b 5
b 6

But i need to display it like this:
a: 1
2
3

b: 4
5
6

What is the best way to do this? I don't think that this is too easy in SQL so I am trying to figure out how to do a loop in my servlet to build this. Do I write a loop with a conditional of some kind?

I am thinking this has a simple solution but I am not seeing it.

Muchas gracias!

[Vijitha Kumara]

Use java.util.Map<String,List<String>> (you can use one of it's implementations, java.util.HashMap perhaps) to store data. I assume you know how to get the data from database?

[Mohamed Khamis]

You can store the first column in a string, for example

String current="", letter;

while(rs.next()){
letter = rs.getString(1);
if (!letter.equals(current))
  {
    current = letter;
    System.out.print(current);
   }
System.out.println(rs.getInt(2));

}

[John Seals]

These are both great tips! Thanks for the quick replies gentlemen.

[Campbell Ritchie]

Welcome to JavaRanch, Mohamed Khamis

[Mohamed Khamis]

Campbell Ritchie wrote:Welcome to JavaRanch, Mohamed Khamis

Thanks glad to be here.