how to handle sql exception in java?

Question

i am trying to create a simple signup form in java. I have made a table in sql in which i have selected not to allow null values but when i signup without entering any values no exception is being given .... all the null values are being excepted..!! What should i do?

private void b1ActionPerformed(java.awt.event.ActionEventevt)                          {                                   
try{


        Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
        Connection con = DriverManager.getConnection("jdbc:odbc:mydsn1");
        PreparedStatement pstmt= con.prepareStatement("insert into project.dbo.signup values(?,?,?,?,?,?)");

        pstmt.setString(1,t1.getText());
        pstmt.setString(2,t2.getText());
        pstmt.setString(3,String.valueOf(t3.getText()));
        pstmt.setString(4,t4.getText());
        pstmt.setString(5,t5.getText());
        pstmt.setString(6,c1.getSelectedItem().toString());

        pstmt.executeUpdate();

    }

    catch(SQLException e)
    {
        JOptionPane.showMessageDialog(null,e.toString());           
    }
      catch(Exception ob)

    {

        JOptionPane.showMessageDialog(null,ob.toString());
    }

}

stinepike · Accepted Answer · 2013-06-22 06:12:49Z

1

Null and empty are not same. If you set a column value as not null then you can not insert any null or you must enter a value. But that doesn't mean that you cannot enter emptry string..

The example of null and emptry string

String s = null;
String s = "";

So in your case, when you are not inserting any input in the TextBox and getting the value using getText() it is returning an empty string not null. I hopy You understood the differenc

So to have an exception you can do one thing. Check the input string if the length is 0 then don't insert it , or insert a null value there like

String s = t1.getText();
if(s.length() == 0)
    pstmt.setString(1, null);  // or dont insert

edited Jun 22, 2013 at 6:12

answered Jun 22, 2013 at 6:07

stinepike

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2 Comments

user2509174 Over a year ago

then how should i imlement what i want..?

user2509174 Over a year ago

there is a function getSelectedItem for a textField ...it wuld return a null value for an empty textfield

Masudul · Accepted Answer · 2013-06-22 06:10:46Z

0

t1.getText() return empty value "" not null. For that you need to check the empty value like

"".equals(t1.getText())

answered Jun 22, 2013 at 6:10

Masudul

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5 Comments

user2509174 Over a year ago

i am an amatuer at java ...it wud be very helpful if u cud edit the code above?

Masudul Over a year ago

String text=t1.getText(); text="".equels(text)? null: text; pstm.setString(1, text); ///Do it for all other filed and assign to pstm.

user2509174 Over a year ago

i wud have to do the code for every textfield..!! isnt there any compact way to do that!!

Masudul Over a year ago

If your all fields are String then use for-loop.

user2509174 Over a year ago

There is a function getSelectedText .it returns null if the textField is blank..!! It pretty much solved my query ..Thnx for your answer it was really helping..!!

Sain Pradeep · Accepted Answer · 2013-06-22 06:16:37Z

0

getText() method, infact, never return null. It returns CharSequence whose contents may be empty.

Instead of doing getText().toString().equals("") or vice-versa, it may be faster to do getText().length() == 0

answered Jun 22, 2013 at 6:16

Sain Pradeep

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1 Comment

user2509174 Over a year ago

i wud have to do the code for every textfield..!! isnt there any compact way to do that!!

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