function return resultset, get in another class - JAVA

Question

I am new in Java. I am doing this thing it creates error, please let me know why I am going in this function dispatchUncaughtException. Am I doing right ? If I am not so how can this thing possible ?

This is dataCollection Class

public class dataCollection {

    private ResultSet my_rs1 =  null;

    public ResultSet mydata()
    {
        try
        {
            String get_data_query = "SELECT * FROM my_table ";
            my_rs1 = cn.stmt.executeQuery(aggregator_data_query);

        } catch(SQLException SQLex)
        {
            System.out.println("SQL Error: " + SQLex.getMessage());
        }

        return my_rs1;        

    }

}

This is callingClass // where we call ResultSet

public class callingClass
{
    dataCollection dc = new dataCollection;
    private ResultSet my_call_data = dc.mydata();
    while(my_call_data.next())
    {
        //Code Here
    }
}

EDIT

Exception in thread "Thread-2" java.lang.NullPointerException
    at sms_sender.dataCollection.aggregator_data(dataCollection.java:29)
    at sms_sender.threadClass.run(threadClass.java:27)

The second snippet will not compile ... I guess a typo. Can you please post a stacktrace? — Fildor, Feb 12 '14 at 12:19
Try doing public ResultSet my_rs1 =null; in dataCollection class ,it might be possible you are trying to access private member outside the scope — ajitksharma, Feb 12 '14 at 12:20
[What is stack trace] http://stackoverflow.com/questions/3988788/what-is-a-stack-trace-and-how-can-i-use-it-to-debug-my-application-errors — AJ., Feb 12 '14 at 12:23
@ALL Please check .. stack trace .. Code which is written in question is example but almost similar. — Google User, Feb 12 '14 at 12:28
You have you error with the stack trace now. Check the line 29 of dataCollection -> NullPointerException means you have probably not initialized correctly a variable. — Laurent B, Feb 12 '14 at 12:42

Mohammed Saqib Rajput · Accepted Answer · 2014-02-13T11:40:37.833

1

correct your parameter :

String get_data_query = "SELECT * FROM my_table";
my_rs1 = cn.stmt.executeQuery(get_data_query);

Edit: Step 2 => Check your db connection its working properly. i think your stmt is empty or incorrect.

edited Feb 13 '14 at 11:40

answered Feb 13 '14 at 11:07

Mohammed Saqib Rajput

1,331
1
14
22

Yeah it was my written mistake. I correct it, but still problem is same. :( – Google User Feb 13 '14 at 11:18
Thx .. It run :). Statement stmt was null. – Google User Feb 13 '14 at 11:57

score 0 · Answer 2 · answered Feb 12 '14 at 12:20

0

code should be in function or block in java.

    public class callingClass
    {
        dataCollection dc = new dataCollection;
        private ResultSet my_call_data;

        public void showData(){
        my_call_data = dc.mydata();
         while(my_call_data.next()){
            //Code Here
         }
       }

    }

answered Feb 12 '14 at 12:20

Shekhar Khairnar

2,643
3
26
44

are you facing the same problem.? – Shekhar Khairnar Feb 12 '14 at 12:37
Almost yes ! I mentioned in my question. – Google User Feb 12 '14 at 12:39

Laurent B · Answer 3 · 2014-02-12T12:37:24.590

What is happening is that you are not catching an Exception so the Thread.UncaughtExceptionHandler will try to forward this Exception.

First try to catch the Exception and give us the stacktrace :

catch (Exception e) {
  e.printStackTrace(); // if you are not using a logger like log4j just print it.
}

Then i would recommend that you read more about Exceptions

And finally, as a notice class names should begin by a Capital letter see Naming Conventions.

Good reading :)

PS : i did not notice that your code was not in a method / function, but i suppose this is just a bad edit as the class would not even compile.

function return resultset, get in another class - JAVA

3 Answers3