CODEWITHSUNDEEP
javamysqlswingnetbeansresultset
Rishav Sharma
Rishav Sharma

Reputation: 35

Best way to print data from two columns of mySQL database to jTextfield one after another

I am trying to make a program in which i read an input from the user i.e. in the textfield named gname and store its value to a string called grammar. Now this input is what sorts my output from the database.

Database looks like this enter image description here

So when user enters G1 in the textfield it should display records in such a way

A->ab,A-ab,B->b

But it only shows 1st element when i use if(myRs.next) and last one if i use while(myRs.next().

current output is enter image description here

Here is the code for this:

its all in try catch block 

String grammar = gname.getText();

        myCon = DriverManager.getConnection("jdbc:mysql://localhost:3306/grammar", "root", "");
        JOptionPane.showMessageDialog(rootPane, "Connected to database");
        mystmt = myCon.createStatement(
                ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_UPDATABLE);
        String query = "SELECT starting_symbol, value from starting_symbol where grammar= '" + grammar + "'";
        String query2 = "SELECT non_terminals, terminals from input_values where grammar= '" + grammar + "'";
        mystmt.addBatch(query);
        mystmt.addBatch(query2);
        myCon.setAutoCommit(false);

        mystmt.addBatch(query);
        mystmt.addBatch(query2);
        myRs = mystmt.executeQuery(query);
        while (myRs.next()) {

            String s = myRs.getString("starting_symbol");
            String val = myRs.getString("value");

            output.setText(s + "-> " + val);

        }
        myRs = mystmt.executeQuery(query2);

        ArrayList<String> list_one = new ArrayList<String>();
        ArrayList<String> list_two = new ArrayList<String>();
        while (myRs.next()) {
            list_one.add(myRs.getString("non_terminals"));
            list_two.add(myRs.getString("terminals"));
            for (int i = 0; i < list_one.size(); i++) {
                output_2.setText(list_one.get(i) + "->" + list_two.get(i));

            }

        }

Please help me in getting the correct outut

Upvotes: 0

Views: 81

Answers (2)

Jarun Jiamtaweeboon
Jarun Jiamtaweeboon

Reputation: 1

Your code snippet can be just like the following:

    StringBuilder sb = new StringBuilder();
    while (myRs.next()) {
        if (sb.length() > 0) sb.append(",");
        sb.append(myRs.getString("non_terminals"))
          .append("->")
          .append(myRs.getString("terminals"));
    }

Instead of calling output_2.setText multiple times that only set the text to be the last fetch value of non_terminals -> terminals in this case B->b.

Upvotes: 0

Sergiy Medvynskyy
Sergiy Medvynskyy

Reputation: 11327

Use StringBuilder Luke

StringBuilder b = new StringBuilder();
while (myRs.next()) {

    String s = myRs.getString("starting_symbol");
    String val = myRs.getString("value");
    if (b.length() > 0) {
        b.append(',');
    }
    b.append(s + "-> " + val);

}
output.setText(b.toString());

And do the same for output_2 field

Upvotes: 1

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