How to store ResultSet in an array of object

Question

I am unable to store the ResultSet in an object array. I want to store it in an Object array and return it, how do I do this?

import java.sql.*;

public class TestSQLwithFunction {
    private static Object[] returnObjectArray() {
         String connnectionURL = "jdbc:sqlserver://localhost\\FAISAL-
         FAS:1433;username=sa;password=password";
         Object ob[] = null;
         try {
             Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
             Connection conn = DriverManager.getConnection(connnectionURL);
             ResultSet rs = conn.getMetaData().getSchemas();
             while(rs.next()) {
                 ob =  (Object[]) rs.getObject(1);
             }
         }
         catch(Exception e){
             e.printStackTrace();
         }
         return ob;
    }


    public static void main (String[] args) {
        Object[] checkrs = returnObjectArray();
        for(int i = 0; i <= checkrs.length; i++){
            System.out.println(checkrs);
        }
    }
}

I get this exception:

java.lang.ClassCastException: java.lang.String cannot be cast to [Ljava.lang.Object; at TestSQLwithFunction.returnObjectArray(TestSQLwithFunction.ja‌​va:13) at TestSQLwithFunction.main(TestSQLwithFunction.java:24) Exception in thread "main" java.lang.NullPointerException at TestSQLwithFunction.main(TestSQLwithFunction.java:25)

Answer 1

You can use object array but you can use collection API also.

Try this:

 private static ArrayList returnObjectArray()throws Exception {
     String connnectionURL = "jdbc:sqlserver://localhost\\FAISAL-FAS:1433;username=sa;password=password";

        ArrayList<Object> data = new ArrayList();

     try {
         Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
         Connection conn = DriverManager.getConnection(connnectionURL);
         ResultSet rs = conn.getMetaData().getSchemas();

         while(rs.next()) {
             data.add(rs.getObject(1));
         }
     }
     catch(Exception e){
         e.printStackTrace();
     }
     return data;
}


public static void main (String[] args) {
    for(Object checkers: returnObjectArray()){
        System.out.println(checkers);
    }
}

I used ArrayList. You can make this more flexible if you want, Using key-value pair. To do this you can use HashMap, HashTable or you can create your own custom one.

If you want custom one:

1. create one class for key-value pair(lets say class name Pair).
2. in Pair class add two variable for key and value.
3. implement constructor: Pair(String key, Object o){//..}
4. then in the returnObjectArray initialize ArrayList<Pair> data = new ArrayList();
5. then add values as data.add(new Pair("column name", rs.getObject(1)))
6. then retrieve values using for-each loop.