How to Iterate Through a Java ResultSet and Extract Data?

Java: Iterating Through a Result Set

In Java, extracting data from a database into a ResultSet is a common task. Consider a query that retrieves the rlink_id and count of occurrences from the dbo.Locate table, grouped by rlink_id. The table contains the following data:

Sid	Lid
3	2
4	4
7	3
9	1

To extract and process this data, it's necessary to loop through the ResultSet. The following Java code demonstrates how to achieve this:

List<String> sids = new ArrayList<>();
List<String> lids = new ArrayList<>();

String query = "SELECT rlink_id, COUNT(*)"
             + "FROM dbo.Locate  "
             + "GROUP BY rlink_id ";

Statement stmt = yourconnection.createStatement();
try {
    ResultSet rs = stmt.executeQuery(query);

    while (rs.next()) {
        sids.add(rs.getString(1));
        lids.add(rs.getString(2));
    }
} finally {
    stmt.close();
}

String[] show = sids.toArray(sids.size());
String[] actuate = lids.toArray(lids.size());

In this code:

1. Two ArrayLists, sids and lids, are initialized to store the rlink_id and count values, respectively.
2. The query string represents the SQL query that retrieves the data.
3. A Statement object is created and used to execute the query.
4. The executeQuery method returns a ResultSet.
5. The while loop iterates through the ResultSet, extracting the rlink_id and count values into the ArrayLists.
6. After processing all rows, the ArrayLists are converted into String arrays for further use in your application.

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